tag:blogger.com,1999:blog-71942102351808232372024-03-13T04:24:45.648-07:00ElectroJeep - All-Electric Jeep CherokeeThis blog documents the conversion process of a 1986 Jeep Cherokee from gasoline to electricRoss Cunniffhttp://www.blogger.com/profile/06668735330276350432noreply@blogger.comBlogger124125tag:blogger.com,1999:blog-7194210235180823237.post-31766802733245864892014-08-05T10:40:00.001-07:002014-08-05T10:40:34.156-07:001000 Lithium Miles<div dir="ltr" style="text-align: left;" trbidi="on">
Yesterday, I passed 1000 miles since I got back on the road with LiFePO4 cells. I've continued to track my daily drives. Here is the chart as of this morning:<br />
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<a href="http://4.bp.blogspot.com/-V9_ECN37fhc/U-ET1FVMWSI/AAAAAAAALe8/EZTvHgepglc/s1600/image.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://4.bp.blogspot.com/-V9_ECN37fhc/U-ET1FVMWSI/AAAAAAAALe8/EZTvHgepglc/s1600/image.png" height="197" width="320" /></a></div>
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You can see that it is very linear - not a lot of variation other than two outliers (both of which happened early on, and both of which were unusual circumstances). From this, some statistics:<br />
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Average daily drive: 15.9 miles<br />
Average daily energy used: 7.13 kWh<br />
Average watt-hours/mile: 424.5<br />
Average mpge: 79.4<br />
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The energy consumption numbers are from the wall and include any charger inefficiencies, etc. The electricity for the average daily drive would cost me 57 cents, if it were not for the fact that much of our electricity comes from our rooftop solar array. Given that the Jeep got 19 mpg in-city on gasoline (on a good day!), I save roughly $950 per year on gasoline at today's price of roughly $3.50 per gallon.<br />
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In related news, I've tracked the efficiency versus temperature. There is not a lot of correlation here:<br />
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<a href="http://1.bp.blogspot.com/-vQtHzqDXLMA/U-EWfWu-2gI/AAAAAAAALfI/rmr3A1YKZ_Q/s1600/mpge_temp.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://1.bp.blogspot.com/-vQtHzqDXLMA/U-EWfWu-2gI/AAAAAAAALfI/rmr3A1YKZ_Q/s1600/mpge_temp.png" height="197" width="320" /></a></div>
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From what I know of LiFePO4, low temperature will affect capacity, not efficiency. Basically, when cold, LiFePO4 sags a lot more than when warm. This translates to fewer watt-hours available, and, since watts required to drive is independent of temperature (if a cabin heater is not included), colder temperature means lower range.</div>
Ross Cunniffhttp://www.blogger.com/profile/06668735330276350432noreply@blogger.com2tag:blogger.com,1999:blog-7194210235180823237.post-13042563570712782102014-06-14T09:37:00.004-07:002014-06-14T09:37:46.270-07:00500 miles on LiFePO4<div dir="ltr" style="text-align: left;" trbidi="on">
Yesterday, the ElectroJeep pushed over the 500 mile mark with its new lithium battery. I've been tracking its performance along the way. First, as detailed <a href="http://electrojeep.blogspot.com/2014/05/parasitic-losses.html" target="_blank">earlier on this blog</a>, it has a "parasitic load" which at this time looks like about 39 milliamps, which translates to about 300 Wh lost per day regardless of whether the ElectroJeep was driven or not. Second, after correcting for this parasitic load, it is getting about 428 Wh/mi wall-to-wheels. This translates to 79 mpge (a standard metric used to compare electric vehicles to others). Compare this to the Jeep's original factory rating of 19 mpg!<br />
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Finally, here is a chart plotting miles driven against kWh used:<br />
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<a href="http://3.bp.blogspot.com/-hEvAaYRlMXc/U5x5bS8Z5GI/AAAAAAAALO0/82iQS-Tjvno/s1600/EJeep_500mi_Li.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://3.bp.blogspot.com/-hEvAaYRlMXc/U5x5bS8Z5GI/AAAAAAAALO0/82iQS-Tjvno/s1600/EJeep_500mi_Li.png" height="197" width="320" /></a></div>
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The red dotted trend line is a least-squares fit to the usage, corrected for the parasitic load. It's very linear, except for that one drive where the ElectroJeep sat idle for a couple of weeks.<br />
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It's exciting how reliable and useful the ElectroJeep is, especially compared to the old lead AGM batteries. It's my daily driver (especially with the Porsche undergoing a similar upgrade). For anybody looking to convert a vehicle, I strongly suggest you save your pennies until you can afford LiFePO4 - you will be much happier in the long run.</div>
Ross Cunniffhttp://www.blogger.com/profile/06668735330276350432noreply@blogger.com0tag:blogger.com,1999:blog-7194210235180823237.post-8153796611332519892014-05-18T08:25:00.000-07:002014-05-18T08:25:40.180-07:00"Parasitic" losses<div dir="ltr" style="text-align: left;" trbidi="on">
A reality of the instrumentation and configuration of the ElectroJeep is that it requires some power even when not in use. Its DC-DC converter is always on, float-charging the accessory battery. Additionally, the MiniBMS modules consume some charge at all times.<br />
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I had the opportunity to measure this the last couple of weeks. For a variety of reasons, I did not end up driving the ElectroJeep between May 2 and May 17. I drove it about 6 miles yesterday, and then charged it. I've been keeping track of the charging energy, and here is what the chart shows, including yesterday:<br />
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<a href="http://3.bp.blogspot.com/-j7IaBZ5NrCU/U3jOeN3tXiI/AAAAAAAAK_Q/NwvUzOYnfnU/s1600/EJeep_Chart_20140518.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://3.bp.blogspot.com/-j7IaBZ5NrCU/U3jOeN3tXiI/AAAAAAAAK_Q/NwvUzOYnfnU/s1600/EJeep_Chart_20140518.png" height="197" width="320" /></a></div>
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Note the little dot way above the trend line on the lower left. That is yesterday. By simplistic calculations, yesterday's drive was expensive at 1135 Wh/mi (compared to the average of about 450 Wh/mi). But a little digging teases out the ongoing parasitic power consumption.<br />
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Yesterday's charge consumed 6.47 kWh. Using the least-squares trend, it should instead have used 3.26 kWh. The difference of 3.21 kWh, divided by the time (15 days), gives the ongoing parasitic power draw: about 8.9 watts. At the typical battery voltage of around 317 volts, this is about 28 milliamps. Looking at it another way, about 0.68 Ah of capacity are used each day, just sitting around. At my "70% DOD" threshold, this means I can leave it idle for about 100 days before needing to charge again.<br />
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Another thing of note: that 28 milliamp draw is too low for my EV Dashboard to detect - it thought the batteries were fairly near "full", even though they had lost about 10 Ah (10% of capacity) over the 15 days of idle time. I may contact the vendor to see if they might consider adding some sort of "correction" factor based on this kind of measurement.</div>
Ross Cunniffhttp://www.blogger.com/profile/06668735330276350432noreply@blogger.com0tag:blogger.com,1999:blog-7194210235180823237.post-41527687141113652632014-04-28T18:30:00.004-07:002014-04-28T18:31:07.631-07:00New Vacuum Pump<div dir="ltr" style="text-align: left;" trbidi="on">
Nearly 5 years ago, <a href="http://electrojeep.blogspot.com/2009/06/power-brakes-and-stuff.html" target="_blank">I installed ElectroJeep's power brake vacuum pump</a>. It was a noisy little beast, and it always irritated me. Some time in the past 5 years, I got a new, quieter pump to replace it - the <a href="http://www.metricmind.com/products/706e2/" target="_blank">MES 70/6E2</a> - but I never got around to installing it because it was taller than the old pump and would not fit in the same spot. However, with the new LiFePO4 layout, I had a blank spot where one of the 26 old AGM batteries had gone. A perfect spot to mount both the new pump as well as the power steering reservoir:<br />
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<a href="http://2.bp.blogspot.com/-PLGS_KErilk/U18AcrYEqoI/AAAAAAAAK1E/FGbZG45v_xc/s1600/IMG_1104.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://2.bp.blogspot.com/-PLGS_KErilk/U18AcrYEqoI/AAAAAAAAK1E/FGbZG45v_xc/s1600/IMG_1104.JPG" height="240" width="320" /></a></div>
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The pump is mounted on little anti-vibration feet, and is much MUCH quieter than the previous pump. I hooked it in to the original vacuum reservoir, which includes an adjustable vacuum sensor switch:<br />
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<a href="http://2.bp.blogspot.com/-yqKH4Yjnbqw/U18ArFNAilI/AAAAAAAAK1M/1A48fQBhB8g/s1600/IMG_1105.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://2.bp.blogspot.com/-yqKH4Yjnbqw/U18ArFNAilI/AAAAAAAAK1M/1A48fQBhB8g/s1600/IMG_1105.JPG" height="240" width="320" /></a></div>
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And now I have power brakes - in style!</div>
Ross Cunniffhttp://www.blogger.com/profile/06668735330276350432noreply@blogger.com0tag:blogger.com,1999:blog-7194210235180823237.post-12198189681512902972014-04-26T18:32:00.000-07:002014-04-26T18:34:03.028-07:00100 Lithium Miles<div dir="ltr" style="text-align: left;" trbidi="on">
Today, the ElectroJeep celebrated 100 miles of Lithium! I've used it as my daily driver all week. I'm very happy with it. I've been keeping track of the power required to charge it - here is a chart as of this week:<br />
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<a href="http://4.bp.blogspot.com/-qnjj9lz0tUU/U1xeeAKoW-I/AAAAAAAAK0Q/Odd1txPx2iQ/s1600/EJeep_100mi.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://4.bp.blogspot.com/-qnjj9lz0tUU/U1xeeAKoW-I/AAAAAAAAK0Q/Odd1txPx2iQ/s1600/EJeep_100mi.jpg" height="195" width="320" /></a></div>
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<a href="https://docs.google.com/spreadsheets/d/1ZQ-21IbDdBrQJ-nSUIj-eBBYiAroJxl10EpuLyinlFs/edit?usp=sharing" target="_blank">You can see the spreadsheet data here </a>- I'll update it every day that I drive. From this data, I can see that my target of "50 miles range" will be met, easily (at least at spring/summer temperatures). I'm getting about 380 Wh/mi range (I had guessed "400"), with a 1.4 kWh "per-charge" overhead. Given that this is a 30.7 kWh pack, that translates directly to a 56 mile range at 70% depth-of-discharge. That would be an 80 mile range at 100% DOD, but that runs the significant risk of killing the pack. Not going to tempt fate.<br />
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Ross Cunniffhttp://www.blogger.com/profile/06668735330276350432noreply@blogger.com0tag:blogger.com,1999:blog-7194210235180823237.post-33337888221852552112014-04-20T17:21:00.000-07:002014-04-20T17:22:04.301-07:00EMW EV Dashboard<div dir="ltr" style="text-align: left;" trbidi="on">
I had previously installed a sender board for the <a href="http://www.emotorwerks.com/products/online-store/category/listing/20-ev-dashboard">EMW EV Dashboard</a> Android app:<br />
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<a href="http://2.bp.blogspot.com/-7V9E8T3AeME/U1RjVDb2N1I/AAAAAAAAKvw/f3be9g6Mg8Y/s1600/IMG_1069.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://2.bp.blogspot.com/-7V9E8T3AeME/U1RjVDb2N1I/AAAAAAAAKvw/f3be9g6Mg8Y/s1600/IMG_1069.JPG" height="240" width="320" /></a></div>
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Today, I hooked up the BlueTooth module and got it calibrated and running to my taste. Here is a screen shot:<br />
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<a href="http://3.bp.blogspot.com/-Jzs1h2UsEmE/U1RXriHyhxI/AAAAAAAAKvc/LR-P8vtxYoA/s1600/14+-+1" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://3.bp.blogspot.com/-Jzs1h2UsEmE/U1RXriHyhxI/AAAAAAAAKvc/LR-P8vtxYoA/s1600/14+-+1" height="200" width="320" /></a></div>
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It shows current (both analog and digital), voltage (both analog and digital), charge (both analog and amp-hours remaining), and power being consumed. I drove about 5 miles around the section block - the app worked really well. And it looks like my estimate of roughly 50 miles range is going to be accurate - I consumed about 7 Ah for the 5 mile range. 70% DOD from 100 Ah is 70 Ah - and 70 Ah * 5 Mi / 7 Ah = 50 miles. To one significant digit.</div>
Ross Cunniffhttp://www.blogger.com/profile/06668735330276350432noreply@blogger.com0tag:blogger.com,1999:blog-7194210235180823237.post-7652408299790409032014-04-20T08:09:00.005-07:002014-04-20T08:10:05.079-07:00It's a vehicle again!<div dir="ltr" style="text-align: left;" trbidi="on">
With everything wired up and functional, it is time for a test drive. So, without further ado - the ElectroJeep rides again!<br />
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<a href="http://4.bp.blogspot.com/-iOaB0ffD1SA/U1PjEDvXKtI/AAAAAAAAKpo/6DGfO5uihO0/s1600/IMG_1103.MOV" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://4.bp.blogspot.com/-iOaB0ffD1SA/U1PjEDvXKtI/AAAAAAAAKpo/6DGfO5uihO0/s1600/IMG_1103.MOV" height="179" width="320" /></a></div>
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It's riding pretty high, so I will probably ratchet back the lift kit to avoid undue stress on the transmission.</div>
Ross Cunniffhttp://www.blogger.com/profile/06668735330276350432noreply@blogger.com0tag:blogger.com,1999:blog-7194210235180823237.post-16626175675449838012014-04-20T08:05:00.000-07:002014-04-20T08:05:27.282-07:00BMS Cell Loop Interconnected<div dir="ltr" style="text-align: left;" trbidi="on">
With the cells interconnected and the BMS modules installed, the critical final step before energizing the whole system is interconnecting the cell loop. Here is the schematic - the interconnects are highlighted in yellow on the diagram:<br />
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<a href="http://3.bp.blogspot.com/-1NW6FLa1veg/U0643JLkbhI/AAAAAAAAKjc/wHAnPs4eU8M/s1600/JeepBMSwiring.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://3.bp.blogspot.com/-1NW6FLa1veg/U0643JLkbhI/AAAAAAAAKjc/wHAnPs4eU8M/s1600/JeepBMSwiring.jpg" height="320" width="229" /></a></div>
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<a href="http://rcunniff.com/GooglePage/JeepBMSwiring.pdf">The PDF of the BMS wiring is here</a>. I had previously built 80-some short interconnects for the tops of the cells. These went on pretty easily. First, the front box:<br />
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<a href="http://2.bp.blogspot.com/-PvUQU8aRLy4/U1Pgbr5a0NI/AAAAAAAAKoo/YD3q350vyz8/s1600/IMG_1089.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://2.bp.blogspot.com/-PvUQU8aRLy4/U1Pgbr5a0NI/AAAAAAAAKoo/YD3q350vyz8/s1600/IMG_1089.JPG" height="240" width="320" /></a></div>
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Next, the upper rear box:<br />
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<a href="http://4.bp.blogspot.com/-urI-Ezlf3w8/U1Pgf2kFO9I/AAAAAAAAKow/n7kg2flBmLA/s1600/IMG_1088.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://4.bp.blogspot.com/-urI-Ezlf3w8/U1Pgf2kFO9I/AAAAAAAAKow/n7kg2flBmLA/s1600/IMG_1088.JPG" height="240" width="320" /></a></div>
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And finally, the lower rear box:<br />
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<a href="http://1.bp.blogspot.com/--NmBy8G5qM4/U1PgkC8dXtI/AAAAAAAAKo4/KTtYm_rYkHc/s1600/IMG_1090.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://1.bp.blogspot.com/--NmBy8G5qM4/U1PgkC8dXtI/AAAAAAAAKo4/KTtYm_rYkHc/s1600/IMG_1090.JPG" height="240" width="320" /></a></div>
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With all the interconnections in place, I did the final torquing of the terminal bolts using my inch-lb torque wrench (9 N*M or roughly 80 inch-lbs per the specs):<br />
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<a href="http://4.bp.blogspot.com/-6gFx9T43h24/U1PhSRtqw2I/AAAAAAAAKpA/sNWzHxakqoM/s1600/IMG_1091.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://4.bp.blogspot.com/-6gFx9T43h24/U1PhSRtqw2I/AAAAAAAAKpA/sNWzHxakqoM/s1600/IMG_1091.JPG" height="320" width="240" /></a></div>
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You'll note it is largely wrapped in electrical tape - safety first! Finally, I hooked up the previously-installed inter-battery-box cabling and plugged the charger in - and it made it safely to its first charge:<br />
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<a href="http://3.bp.blogspot.com/-ZhfFqpQE8_U/U1PhlYx1ZgI/AAAAAAAAKpI/55yWRyGJPJE/s1600/IMG_1099.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://3.bp.blogspot.com/-ZhfFqpQE8_U/U1PhlYx1ZgI/AAAAAAAAKpI/55yWRyGJPJE/s1600/IMG_1099.JPG" height="240" width="320" /></a></div>
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So, with wheels turning and charger functioning - it is a car! Up next - a test drive.</div>
Ross Cunniffhttp://www.blogger.com/profile/06668735330276350432noreply@blogger.com0tag:blogger.com,1999:blog-7194210235180823237.post-33377224757021864892014-04-13T13:35:00.001-07:002014-04-13T13:35:49.438-07:00It's Alive (again)!<div dir="ltr" style="text-align: left;" trbidi="on">
With all of the batteries interconnected, I finally turned the controller on for the first time in nearly two years. I was pleasantly surprised to see that it came right up. I hooked up my little Windows XP notebook (kept for just this purpose) and tweaked the settings for the new voltage levels:<br />
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<a href="http://1.bp.blogspot.com/-20X3ceCxxMo/U0r0CuaUkKI/AAAAAAAAKg8/Djy3UJZXpro/s1600/IMG_1087.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://1.bp.blogspot.com/-20X3ceCxxMo/U0r0CuaUkKI/AAAAAAAAKg8/Djy3UJZXpro/s1600/IMG_1087.JPG" height="240" width="320" /></a></div>
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The four key parameters I changed were:<br />
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<ul style="text-align: left;">
<li>EE2NoAccelBat - this is the voltage level below which no current should be drawn. I set it to 2.8V per cell, or 268.8V total</li>
<li>EE2NoRegenBat - this is the maximum voltage above which no regenerative braking will occur. This is set lower than the charge current to keep the cells from overcharging and causing the MiniBMS to haz a sad. I set it to 3.4V per cell, or 326.4V total</li>
<li>EE2PSHighBatVoltage - I don't know what this is for, but I set it to the charge cutoff voltage of 3.5V per cell, or 336V</li>
<li>EE2PSLimitBatVoltage - I don't know what this is for, either, but I set it to the maximum I ever want to see on these cells, 3.6V per cell, or 345.6V total</li>
</ul>
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With the parameters established, I put the Jeep in neutral, then turned the handle to "drive enable." Pushing the throttle spun the motor! So I put it in first and drove forward a couple of inches. Victory!</div>
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It's not ready to drive around the neighborhood, yet - I need to finish the BMS wiring and do some other miscellaneous mechanical / cosmetic work. But this is a significant milestone.</div>
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Ross Cunniffhttp://www.blogger.com/profile/06668735330276350432noreply@blogger.com0tag:blogger.com,1999:blog-7194210235180823237.post-46195678170436279792014-04-13T13:27:00.000-07:002014-04-13T13:27:10.717-07:00Cells Interconnected!<div dir="ltr" style="text-align: left;" trbidi="on">
Before interconnecting the cells, I spent some time yesterday making sure everything was ready. I added orange flex-guard around all of the exposed HV cables, and modified my power junction box to be more easily accessible (but still covered to keep curious fingers away):<br />
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<a href="http://1.bp.blogspot.com/-zqP_kQdGtGU/U0ryxfwDM3I/AAAAAAAAKgk/K-A5xBUEV4A/s1600/IMG_1071.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://1.bp.blogspot.com/-zqP_kQdGtGU/U0ryxfwDM3I/AAAAAAAAKgk/K-A5xBUEV4A/s1600/IMG_1071.JPG" height="320" width="240" /></a></div>
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I also mounted the 10A fuse for the DC-DC converter in an electronics box:<br />
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<a href="http://4.bp.blogspot.com/-pg3BRmMf9rg/U0ry5E3EVHI/AAAAAAAAKgs/D85Nkn7HmTk/s1600/IMG_1072.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://4.bp.blogspot.com/-pg3BRmMf9rg/U0ry5E3EVHI/AAAAAAAAKgs/D85Nkn7HmTk/s1600/IMG_1072.JPG" height="320" width="240" /></a></div>
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Finally, last night and this morning I interconnected all the cells. There are three steps to interconnecting the cells. First, I smear the terminal posts with a little anti-oxidant grease (NoAlOx or equivalent). I then use an emery cloth to remove the oxide layer from both posts. Then I put battery interconnects, MiniBMS modules, and M8 bolts/washers on. For safety, I follow a routine when putting the interconnects on. First, an M8 bolt is threaded through an interconnect to a cell which is not connected to anything. It is not tightened, it just needs to be enough to keep that end of the interconnect from moving. The interconnect in the lower middle has just had this done:<br />
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<a href="http://2.bp.blogspot.com/-mwf0rCKFtrs/U0rv-lbazCI/AAAAAAAAKfg/Ar-eqOEZFL4/s1600/IMG_1075.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://2.bp.blogspot.com/-mwf0rCKFtrs/U0rv-lbazCI/AAAAAAAAKfg/Ar-eqOEZFL4/s1600/IMG_1075.JPG" height="240" width="320" /></a></div>
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Next, I attach a MiniBMS module across the previous cell in the string, making sure to put the negative terminal on the negative post:<br />
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<a href="http://4.bp.blogspot.com/-TgThFaxrO3c/U0rwMVpeqII/AAAAAAAAKfo/MmG31bCXvEc/s1600/IMG_1076.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://4.bp.blogspot.com/-TgThFaxrO3c/U0rwMVpeqII/AAAAAAAAKfo/MmG31bCXvEc/s1600/IMG_1076.JPG" height="240" width="320" /></a></div>
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I tighten down both bolts finger-tight (I will later use an inch-lb torque wrench to finalize the connections). With that done, I remove the M8 bolt that I previously placed:<br />
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<a href="http://2.bp.blogspot.com/-A_bBi0ibKzQ/U0rwaQ5Ye-I/AAAAAAAAKfw/i-U1cJYMZRg/s1600/IMG_1077.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://2.bp.blogspot.com/-A_bBi0ibKzQ/U0rwaQ5Ye-I/AAAAAAAAKfw/i-U1cJYMZRg/s1600/IMG_1077.JPG" height="240" width="320" /></a></div>
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This is done in this specific order to prevent unintentional short-circuits. Without doing it in this order, it is possible that the interconnect you are working on will rotate over and close the circuit with the adjacent string. This would be Very Bad - there are places on the battery string where 26 volts of potential exist between adjacent terminals. The cells can deliver 1000A or more of current for a significant amount of time (tens of seconds). A 26+ kW plasma event would be a very bad day, indeed (and you would not want to put your hand in there to disconnect anything!), leading to at least several destroyed cells and BMS modules, and at most a vehicle-destroying fire or even severe injury or death. Obviously, I experienced none of those things. You will also note that my finger socket drive and socket are wrapped in electrical tape to reduce the chances of unintentional short-circuits.<br />
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With safety always in mind, I completed the interconnect of all the cells. Here is the upper rear box glowing happily:<br />
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<a href="http://1.bp.blogspot.com/-RwHI06PLGRI/U0rxzaoDChI/AAAAAAAAKf8/Ng0fGPnPfm4/s1600/IMG_1073.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://1.bp.blogspot.com/-RwHI06PLGRI/U0rxzaoDChI/AAAAAAAAKf8/Ng0fGPnPfm4/s1600/IMG_1073.JPG" height="320" width="240" /></a></div>
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And the lower rear box, also happy:<br />
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<a href="http://1.bp.blogspot.com/-e4fSGNTJdKM/U0rx337jkLI/AAAAAAAAKgE/Ms7L_UuexLs/s1600/IMG_1078.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://1.bp.blogspot.com/-e4fSGNTJdKM/U0rx337jkLI/AAAAAAAAKgE/Ms7L_UuexLs/s1600/IMG_1078.JPG" height="240" width="320" /></a></div>
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During this process, I found one dead cell and one cell with a loose remote BMS wire. This stymied me for the evening, but I was back at it this morning, finishing the front box:<br />
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<a href="http://1.bp.blogspot.com/-1KYbSFeHDeU/U0ryEAT-DtI/AAAAAAAAKgM/rWXUxRAk8JE/s1600/IMG_1080.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://1.bp.blogspot.com/-1KYbSFeHDeU/U0ryEAT-DtI/AAAAAAAAKgM/rWXUxRAk8JE/s1600/IMG_1080.JPG" height="240" width="320" /></a></div>
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and hooking up the BMS modules under the seats:<br />
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<a href="http://2.bp.blogspot.com/-j8CDzmR-fo0/U0ryLkZEDoI/AAAAAAAAKgU/22KodyiLHhs/s1600/IMG_1082.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://2.bp.blogspot.com/-j8CDzmR-fo0/U0ryLkZEDoI/AAAAAAAAKgU/22KodyiLHhs/s1600/IMG_1082.JPG" height="240" width="320" /></a></div>
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With 96 cells all happy, I hooked up the service disconnects, and measured the voltage at the junction box:<br />
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<a href="http://3.bp.blogspot.com/-yKPgU3u0uhs/U0ryXCgaiSI/AAAAAAAAKgc/LYhXYNMbpeY/s1600/IMG_1085.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://3.bp.blogspot.com/-yKPgU3u0uhs/U0ryXCgaiSI/AAAAAAAAKgc/LYhXYNMbpeY/s1600/IMG_1085.JPG" height="320" width="240" /></a></div>
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321.9 volts - about 3.35 volts per cell - perfect! Next up, tuning the controller.</div>
Ross Cunniffhttp://www.blogger.com/profile/06668735330276350432noreply@blogger.com0tag:blogger.com,1999:blog-7194210235180823237.post-15191097088103445272014-04-13T12:53:00.000-07:002014-04-13T13:10:49.504-07:00Custom Interconnects<div dir="ltr" style="text-align: left;" trbidi="on">
I finally got a couple of weeks to work on the ElectroJeep. First order of business was finalizing the battery layout and interconnects. Here is the final layout:<br />
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<a href="http://4.bp.blogspot.com/-cDvDq6VbcyA/U0riO9BlpLI/AAAAAAAAKd8/AQrGEsNyJVY/s1600/ElectroJeepBatteryCabling.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://4.bp.blogspot.com/-cDvDq6VbcyA/U0riO9BlpLI/AAAAAAAAKd8/AQrGEsNyJVY/s1600/ElectroJeepBatteryCabling.jpg" height="198" width="320" /></a></div>
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<a href="http://rcunniff.com/GooglePage/ElectroJeepBatteryCabling.pdf">You can download a PDF of the ElectroJeep battery layout here</a>. From left to right, the five battery boxes are named "front", "passenger's side under seat", "driver's side under seat", "upper rear", and "lower rear." One significant change from the previous version is that the most positive terminal is now in the upper rear box rather than the lower rear box. This was done to simplify the HV cable tangle at the front left of the lower rear box.<br />
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Note that there are several "odd" interconnects in the upper rear and lower rear battery boxes. The task a couple of weeks ago was to actually manufacture the interconnects. I created some patterns which I printed out on 8.5x11 paper. The first is for the "turnarounds" - the two spots in the upper rear box which require a parity reversal on the cells' positive and negative terminals:<br />
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<a href="http://2.bp.blogspot.com/--OaGNcDa-Uk/U0rjNmEoChI/AAAAAAAAKeE/mtuPIsAnVT8/s1600/TurnAround.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://2.bp.blogspot.com/--OaGNcDa-Uk/U0rjNmEoChI/AAAAAAAAKeE/mtuPIsAnVT8/s1600/TurnAround.jpg" height="320" width="199" /></a></div>
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<a href="http://rcunniff.com/GooglePage/TurnAround.pdf">The PDF file for the turnarounds is here</a>. The second is for the "odd interconnects" - the L-shaped interconnects and the longer interconnect in the upper left corner of the lower rear box:<br />
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<a href="http://1.bp.blogspot.com/-APw0LAMHQf4/U0rjWOvIbTI/AAAAAAAAKeQ/CH8WYRN-6ps/s1600/OddInterconnects.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://1.bp.blogspot.com/-APw0LAMHQf4/U0rjWOvIbTI/AAAAAAAAKeQ/CH8WYRN-6ps/s1600/OddInterconnects.jpg" height="320" width="250" /></a></div>
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<a href="http://rcunniff.com/GooglePage/OddConnects.pdf">Again, the PDF for the odd interconnects is here</a>. I used double-sided tape behind each thing I wanted to cut out, stuck the pattern to a sheet of 0.02" copper, and cut them out with sheet-metal shears. I then used my hole punch to punch out 5/16" holes, then stacked them together and used heat-shrink to bond them. Here are the completed turn-arounds:<br />
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<a href="http://2.bp.blogspot.com/-Hlu1M0PCziI/U0rkDBjk6LI/AAAAAAAAKeU/PlxHs2PTP5Y/s1600/IMG_1066.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://2.bp.blogspot.com/-Hlu1M0PCziI/U0rkDBjk6LI/AAAAAAAAKeU/PlxHs2PTP5Y/s1600/IMG_1066.JPG" height="320" width="240" /></a></div>
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Each one is made from a stack of six cut-outs. I designed them to be 22mm wide - basically, 0.9" - and 0.9" times 0.12" (the combined thickness) is 0.108 in^2, the cross-sectional area. This is approximately the same as 2/0 gauge welding cable (0.105 in^2), which is what I'm using as the main cable size.<br />
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I also used a double stack of 1/16" by 3/4" copper straps in two places - between the EV display and a cell terminal, and between the CamLok inlet to the upper rear battery box. This is 0.094 in^2, which is a little smaller than 2/0 cable (but about the same as the copper interconnects that come with the cells). Here is the double strap behind the EV display:<br />
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<a href="http://4.bp.blogspot.com/-E85RKl2sah0/U0robgA9WOI/AAAAAAAAKek/5GKTuPpAhjQ/s1600/IMG_1069.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://4.bp.blogspot.com/-E85RKl2sah0/U0robgA9WOI/AAAAAAAAKek/5GKTuPpAhjQ/s1600/IMG_1069.JPG" height="240" width="320" /></a></div>
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You can also see the massive 400A 500VDC fuse to the left of the EV display, and the edge of a 30A 500VDC fuse holder on the right (which protects the charger wiring). These are shown on the updated HV circuit diagram:<br />
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<a href="http://1.bp.blogspot.com/-tawxo5qThEs/U0rvB2JwdPI/AAAAAAAAKfc/5qEsk_5YE1c/s1600/ElectroJeepHVnew.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://1.bp.blogspot.com/-tawxo5qThEs/U0rvB2JwdPI/AAAAAAAAKfc/5qEsk_5YE1c/s1600/ElectroJeepHVnew.jpg" height="320" width="247" /></a></div>
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<a href="http://rcunniff.com/GooglePage/ElectroJeepHVnew.pdf">The PDF for the HV circuit diagram is here</a>. And, finally, here are the interconnects in their places (you can also see the CamLok connector in place in the upper rear battery box):<br />
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<a href="http://4.bp.blogspot.com/-pqO__x0XiVE/U0rp276ZgLI/AAAAAAAAKe4/H0BW8fu-9gs/s1600/IMG_1068.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://4.bp.blogspot.com/-pqO__x0XiVE/U0rp276ZgLI/AAAAAAAAKe4/H0BW8fu-9gs/s1600/IMG_1068.JPG" height="240" width="320" /></a></div>
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Next up (finally!) - interconnecting the cells.</div>
Ross Cunniffhttp://www.blogger.com/profile/06668735330276350432noreply@blogger.com0tag:blogger.com,1999:blog-7194210235180823237.post-13227497602781840012013-10-13T19:29:00.002-07:002013-10-13T19:29:50.646-07:00Finishing battery box lids<div dir="ltr" style="text-align: left;" trbidi="on">
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I finished the battery box lids this weekend. First, I found that the epoxy I used just did not have enough shear strength - the shear force I put on the hold-downs while I used a router to cut grooves for interconnects to pass under was enough to pop some of the hold-downs off the acrylic top. So, it's nuts and screws for the hold-downs to augment the epoxy. All of the screws and nuts are countersunk so that they don't have any chance of interfering with anything:</div>
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<a href="http://3.bp.blogspot.com/-N6iOqKTfizI/UltWEuHESqI/AAAAAAAAGa8/Qnpt3O8TcpU/s1600/01_ScrewTops.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://3.bp.blogspot.com/-N6iOqKTfizI/UltWEuHESqI/AAAAAAAAGa8/Qnpt3O8TcpU/s320/01_ScrewTops.jpg" width="320" /></a></div>
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Next, I applied 3/16"-thick foam weatherstripping to the acrylic lids. This is to provide some vibration resistance, as well as some resilience so that everything stays nice and tight under compression. Here is the lower rear cover (you can see some of the gaps that I routed out in this picture as well):<br />
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<a href="http://4.bp.blogspot.com/-W8JIHDhGmNI/UltWEdVL6HI/AAAAAAAAGa4/1HR0ESm3x9Q/s1600/02_FoamBottoms.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://4.bp.blogspot.com/-W8JIHDhGmNI/UltWEdVL6HI/AAAAAAAAGa4/1HR0ESm3x9Q/s320/02_FoamBottoms.jpg" width="320" /></a></div>
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Finally, I also applied the 3/16"-thick foam to the metal box tops. Again, to reduce vibration and to keep everything tight when compressed with the nuts/bolts that hold this all together:<br />
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<a href="http://2.bp.blogspot.com/-bTfXYoDDSo0/UltWETXAR5I/AAAAAAAAGbE/c8C0u8E0drE/s1600/03_MetalFoam.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://2.bp.blogspot.com/-bTfXYoDDSo0/UltWETXAR5I/AAAAAAAAGbE/c8C0u8E0drE/s320/03_MetalFoam.jpg" width="320" /></a></div>
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One last step before battery interconnecting - I need to add material to keep the cells in-place horizontally (they don't quite fill up the space that the former AGM-1280T batteries occupied).</div>
Ross Cunniffhttp://www.blogger.com/profile/06668735330276350432noreply@blogger.com0tag:blogger.com,1999:blog-7194210235180823237.post-51849710457413230612013-10-06T18:31:00.002-07:002013-10-06T18:31:58.535-07:00Battery Box Covers<div dir="ltr" style="text-align: left;" trbidi="on">
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Although a vacation interrupted progress on the ElectroJeep in September, it is getting very close to energizing the main HV circuits. However, before that happens, I want non-conductive covers in place to protect against mishaps. Since orange is the new black, I went with orange acrylic covers, with 3/4" by 7/8" clear acrylic blocks to hold the cells down by their edges. Here are the hold-downs epoxied to the covers, resting in their respective racks:</div>
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<a href="http://4.bp.blogspot.com/-Q-uehPB7Pt8/UlINRQiKnCI/AAAAAAAAGaQ/oOsrwhsR7co/s1600/01_TopsInRacks.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://4.bp.blogspot.com/-Q-uehPB7Pt8/UlINRQiKnCI/AAAAAAAAGaQ/oOsrwhsR7co/s320/01_TopsInRacks.jpg" width="320" /></a><br />
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The front rack is simplest - just 4 parallel blocks:<br />
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<a href="http://3.bp.blogspot.com/-pc22QPURKbg/UlINRQMuwmI/AAAAAAAAGaI/JmEGesKdlSE/s1600/02_FrontCover.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://3.bp.blogspot.com/-pc22QPURKbg/UlINRQMuwmI/AAAAAAAAGaI/JmEGesKdlSE/s320/02_FrontCover.jpg" width="320" /></a></div>
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The upper rear rack is also fairly simple - 9 parallel blocks:<br />
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<a href="http://2.bp.blogspot.com/-N1RYYvkmTuk/UlINRp83MmI/AAAAAAAAGaM/PgiiLBI-tv0/s1600/03_UpperRearCover.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://2.bp.blogspot.com/-N1RYYvkmTuk/UlINRp83MmI/AAAAAAAAGaM/PgiiLBI-tv0/s320/03_UpperRearCover.jpg" width="320" /></a></div>
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The lower rear rack is more complicated due to the different cell orientations. There are 7 parallel blocks, and two additional blocks at 90 degrees to hold down the 7 cells at the front of the rack:<br />
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<a href="http://2.bp.blogspot.com/-Ganp-XzBe5M/UlINR2hHIHI/AAAAAAAAGaU/PzFJCU5gWSA/s1600/04_LowerRearCover.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://2.bp.blogspot.com/-Ganp-XzBe5M/UlINR2hHIHI/AAAAAAAAGaU/PzFJCU5gWSA/s320/04_LowerRearCover.jpg" width="320" /></a></div>
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The final step will be to add self-adhesive foam between the blocks and the cells, and between the rack-tops and the covers - this is all to reduce vibration and to keep everything in compression.<br />
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The under-seat cells will reuse the polypropylene covers - there is not room on top of the cells for the BMS boards, so a simpler hold-down will work well. However, I need BMS modules. So, I reused two of the boxes I built for the old AGM BMS, and mounted 3 BMS boards in each one:<br />
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<a href="http://1.bp.blogspot.com/-p_D1kH0AibE/UlINR4jagsI/AAAAAAAAGao/04eAj0vaPWY/s1600/05_UnderSeatBMS.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://1.bp.blogspot.com/-p_D1kH0AibE/UlINR4jagsI/AAAAAAAAGao/04eAj0vaPWY/s320/05_UnderSeatBMS.jpg" width="320" /></a></div>
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The bolts that the BMS is attached to do not go all the way through the box - there is an inner floor that they are bolted to. The inner floor is then bolted to the outer floor to keep everything in place.<br />
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So - I think I can start interconnecting cells safely now. And then to re-energize the controller, the DC-DC converter, the voltmeter, and the new charger...<br />
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Ross Cunniffhttp://www.blogger.com/profile/06668735330276350432noreply@blogger.com0tag:blogger.com,1999:blog-7194210235180823237.post-81088639959044040502013-09-02T19:56:00.001-07:002013-09-03T16:20:23.942-07:00BMS Wiring, Part 1<div dir="ltr" style="text-align: left;" trbidi="on">
Today, I did some wiring toward getting the BMS in place.<br />
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First, I added some wires in the passenger's side of the rear compartment. The green extension cord plug will eventually be the 120VAC battery warming power supply. The green cord going into the cable gland and the silver thermocouple wire are also for the battery warming system (for the front box). The white extension cord is for the BMS loop:<br />
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<a href="http://4.bp.blogspot.com/-dfS21ywq0Vs/UiVNjgUiQlI/AAAAAAAAGXE/w3Iv53oadTs/s1600/01_PassRearWires.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://4.bp.blogspot.com/-dfS21ywq0Vs/UiVNjgUiQlI/AAAAAAAAGXE/w3Iv53oadTs/s320/01_PassRearWires.jpg" width="320" /></a></div>
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Here is the inlet for the battery warming plug. I'm not going to do much more on this part for now (it's still pretty warm :-) but I wanted to get the hole-drilling and cable pulling out of the way:<br />
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<a href="http://1.bp.blogspot.com/-ELTdUT0seNI/UiVNj52R3sI/AAAAAAAAGXI/fKwhGD59BTE/s1600/02_HeaterInlet.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://1.bp.blogspot.com/-ELTdUT0seNI/UiVNj52R3sI/AAAAAAAAGXI/fKwhGD59BTE/s320/02_HeaterInlet.jpg" width="320" /></a></div>
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The green, white, and silver cables go through the floor of the rear compartment to this LiquiTight conduit gland:</div>
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<a href="http://3.bp.blogspot.com/-94WMRcwj1qw/UiVNj49ft2I/AAAAAAAAGXQ/qJkmkK185CQ/s1600/03_ConduitEntry.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://3.bp.blogspot.com/-94WMRcwj1qw/UiVNj49ft2I/AAAAAAAAGXQ/qJkmkK185CQ/s320/03_ConduitEntry.jpg" width="320" /></a></div>
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The conduit proceeds forward along the wheel well...<br />
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<a href="http://2.bp.blogspot.com/-QqaXwBukT9Q/UiVNkRMHIQI/AAAAAAAAGXk/hSXHpy2UE7Q/s1600/04_ConduitAboveWheel.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://2.bp.blogspot.com/-QqaXwBukT9Q/UiVNkRMHIQI/AAAAAAAAGXk/hSXHpy2UE7Q/s320/04_ConduitAboveWheel.jpg" width="320" /></a></div>
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...under the passenger-side rocker...<br />
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<a href="http://3.bp.blogspot.com/-8MpkJNF-r4M/UiVNkSdBPmI/AAAAAAAAGXg/rzShll_fh3A/s1600/05_ConduitForward.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="http://3.bp.blogspot.com/-8MpkJNF-r4M/UiVNkSdBPmI/AAAAAAAAGXg/rzShll_fh3A/s320/05_ConduitForward.jpg" width="240" /></a></div>
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...and ends up in the engine compartment. The silver thermocouple will go into the battery box; the white as mentioned will carry the BMS loop to these cells.<br />
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<a href="http://3.bp.blogspot.com/-UL39seMIstI/UiVNkuGlD_I/AAAAAAAAGXc/gDpC4TWY0ng/s1600/06_CableEnd.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://3.bp.blogspot.com/-UL39seMIstI/UiVNkuGlD_I/AAAAAAAAGXc/gDpC4TWY0ng/s320/06_CableEnd.jpg" width="320" /></a></div>
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With the cabling out of the way, I wired up the BMS controller. I went back and forth on whether to put this under the dash or in the rear - in either case, we needed some signals routed between front and back. The deciding factor was that this placement is much more convenient to work on:</div>
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<a href="http://1.bp.blogspot.com/-wMItkRik1Z4/UiVNlIkd7zI/AAAAAAAAGX8/6nNxYAgFJKA/s1600/07_BMS_Wiring.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://1.bp.blogspot.com/-wMItkRik1Z4/UiVNlIkd7zI/AAAAAAAAGX8/6nNxYAgFJKA/s320/07_BMS_Wiring.jpg" width="320" /></a></div>
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Here is everything all closed up and connected. I tried plugging an EVSE in to see whether the kWh meter lit (and the charger light lit) but, no joy in Mudville tonight - the EVSE flashed a "line cord fault" indication. I suspect I have the pilot and control lines reversed. But for now, this *looks* pretty:<br />
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<a href="http://3.bp.blogspot.com/-L_Husj6VPcA/UiVNlaKKG_I/AAAAAAAAGX4/7FLsOXRUGmk/s1600/08_WiringDone.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://3.bp.blogspot.com/-L_Husj6VPcA/UiVNlaKKG_I/AAAAAAAAGX4/7FLsOXRUGmk/s320/08_WiringDone.jpg" width="320" /></a></div>
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Here is the wiring diagram for the BMS. I have not yet done the inter-cell connections (shown here in magenta, but I'll use white wires). <a href="http://rcunniff.com/GooglePage/JeepBMSwiring.pdf">The PDF of this diagram can be found at this link.</a><br />
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<a href="http://1.bp.blogspot.com/-bM5cDQvEx4Q/UiVNlvgpimI/AAAAAAAAGX0/RBnrQSsiHHU/s1600/09_JeepBMSwiring.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="http://1.bp.blogspot.com/-bM5cDQvEx4Q/UiVNlvgpimI/AAAAAAAAGX0/RBnrQSsiHHU/s320/09_JeepBMSwiring.png" width="247" /></a></div>
So, this is probably as far as I get for the next few weeks - but I look forward to finishing the BMS wiring and trying a quick top-off charge cycle...<br />
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<b>EDIT Sep 3 2013:</b> Swapping the PRX and PIL lines on the J1772 AVC1 unit fixed the problem! I verified that all the other circuity is installed properly and working - connecting the cell loop (with no cells) causes the charge relay to engage, the 12V power supply is working, and everything seems happy. The <a href="http://rcunniff.com/GooglePage/JeepJ1772.pdf">circuit diagram</a> for that circuitry has been updated, as has been the previous post.<br />
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Ross Cunniffhttp://www.blogger.com/profile/06668735330276350432noreply@blogger.com0tag:blogger.com,1999:blog-7194210235180823237.post-70388827665367947342013-09-01T09:06:00.003-07:002013-09-03T16:20:17.559-07:00Charger Control Electronics<div dir="ltr" style="text-align: left;" trbidi="on">
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"Well, we've tried every device and you still won't talk - every device, that is, except for this little baby we simply call 'Mr. Thingy.'":</div>
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<a href="http://4.bp.blogspot.com/-lXjMsQ3NbNI/UiNj-Heq6gI/AAAAAAAAGWw/S_Q4Wh6eoWA/s1600/01_MrThingyGuts.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="http://4.bp.blogspot.com/-lXjMsQ3NbNI/UiNj-Heq6gI/AAAAAAAAGWw/S_Q4Wh6eoWA/s320/01_MrThingyGuts.JPG" width="240" /></a></div>
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OK, perhaps a little more explanation than this obscure Far Side reference is in order. As mentioned before, with top-balanced lithium cells, you need to shut off charging current if any cell hits the high-voltage cutoff point (3.6V in my case). Some chargers have ways to do this with a signal from the BMS. But every charger is different. I may want to change chargers some day, and in fact may want to experiment with an off-board charger for fast charging, so I created Mr. Thingy. All Mr. Thingy does is provide a place to mount:<br />
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<ol style="text-align: left;">
<li>A 40-amp solid state AC relay which can turn off the charger in a high-voltage-cutoff event</li>
<li>The circuit board which handles the J1772 pilot and control signals</li>
<li>The 12 volt power supply which powers both the relay coil as well as the "I'm plugged in, don't drive away you dummy!" light and interlock</li>
<li>A kilowatt-hour meter to keep track of electricity used during charging</li>
<li>Various plugs and receptacles to make switching between J1772 and a regular extension cord, and between the on-board charger and an off-board charger, convenient</li>
</ol>
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All of this in an 8x8x4 inch box! Here is the circuit diagram:</div>
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<a href="http://2.bp.blogspot.com/-JGoMpfATlBA/UiNj9oUmkKI/AAAAAAAAGWg/89z42gRlMEk/s1600/02_JeepJ1772.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="247" src="http://2.bp.blogspot.com/-JGoMpfATlBA/UiNj9oUmkKI/AAAAAAAAGWg/89z42gRlMEk/s320/02_JeepJ1772.png" width="320" /></a></div>
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<a href="http://rcunniff.com/GooglePage/JeepJ1772.pdf">You can find the PDF of this circuit diagram here</a>. And here is the completed enclosure, mounted and attached:<br />
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<a href="http://1.bp.blogspot.com/-iqE3Jv7bNTY/UiNj9qoKHiI/AAAAAAAAGWk/WKtyv7BuvPY/s1600/03_MrThingyDone.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://1.bp.blogspot.com/-iqE3Jv7bNTY/UiNj9qoKHiI/AAAAAAAAGWk/WKtyv7BuvPY/s320/03_MrThingyDone.JPG" width="320" /></a></div>
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For those who do not want to open the PDF, here is the note from that PDF explaining operation:<br />
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If the inlet 10-30P plug “B” is unplugged from the J1772, then the AVC1 will not have ground and will therefore not handshake with the J1772 EVSE, preventing any power from being present on the 10-30R receptacle labelled “A”. This is intentional.<br />
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When unplugged from the J1772, the 10-30P plug labelled “B” may be plugged in to a NEMA 10-30R receptacle for direct charging. The on-board charger can be unplugged from the 10-30R receptacle labelled “C” and another charger plugged into it for higher-power BMS-controlled charging.<br />
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J1772 Inlet from Tucson EV has the 2.74k ohm resistor preinstalled between PRX and ground.<br />
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All high-current 240VAC power wiring is 10 AWG.<br />
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<b>EDIT Sep 3 2013:</b> <a href="http://electrojeep.blogspot.com/2013/09/bms-wiring-part-1.html">Per this post</a>, this did not quite work initially - the EVSE indicated a "line fault" . Swapping the PRX and PIL lines on the J1772 AVC1 unit fixed the problem! I verified that all the other circuity is installed properly and working - connecting the cell loop (with no cells) causes the charge relay to engage, the 12V power supply is working, and everything seems happy. The <a href="http://rcunniff.com/GooglePage/JeepJ1772.pdf">circuit diagram</a> for this circuitry has been updated, and now matches this updated PNG:<br />
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<a href="http://1.bp.blogspot.com/-7NLVK-XQs1k/UiZuZc5AMEI/AAAAAAAAGYU/-5Sqx2etjTw/s1600/JeepJ1772a.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="255" src="http://1.bp.blogspot.com/-7NLVK-XQs1k/UiZuZc5AMEI/AAAAAAAAGYU/-5Sqx2etjTw/s320/JeepJ1772a.png" width="320" /></a></div>
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Ross Cunniffhttp://www.blogger.com/profile/06668735330276350432noreply@blogger.com0tag:blogger.com,1999:blog-7194210235180823237.post-9544472671808712652013-09-01T07:37:00.002-07:002013-09-01T09:12:53.500-07:00Strapping the Cells<div dir="ltr" style="text-align: left;" trbidi="on">
In the earlier days of DIY lithium conversions, conventional wisdom was that batteries needed to be tightly strapped - even so far as using threaded rod and metal plates to compress them together. It was believed that this prevented bulging - kind of like keeping the smoke from escaping. It turns out that bulging is entirely avoidable - just don't abuse your cells with over-charging or over-discharging. However, it is convenient mechanically to group the cells together. It makes it easier to load them in the racks, too. So I got some poly strapping equipment and banded most of the cells in groups of 3, 4, or 5.<br />
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Use is pretty straightforward. Place a length of strap around the thing you want to bind, and put a metal clip in place, then thread the strap through the ratcheting strapping machine:<br />
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<a href="http://2.bp.blogspot.com/-1bIbYQX2V7I/UiNQjHaQdjI/AAAAAAAAGWE/GqX_MEMvDvk/s1600/18_PlaceStrapper.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://2.bp.blogspot.com/-1bIbYQX2V7I/UiNQjHaQdjI/AAAAAAAAGWE/GqX_MEMvDvk/s320/18_PlaceStrapper.JPG" width="320" /></a></div>
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Tension the strap as desired (being careful not to over-tension), and then crimp the metal clip (you can also see the crimper on the work bench at the right of the picture above):<br />
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<a href="http://2.bp.blogspot.com/-ieemwgsUvYM/UiNQjSQMLII/AAAAAAAAGWM/Igtt5puAjJQ/s1600/19_Crimp.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://2.bp.blogspot.com/-ieemwgsUvYM/UiNQjSQMLII/AAAAAAAAGWM/Igtt5puAjJQ/s320/19_Crimp.JPG" width="320" /></a></div>
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Once crimped, press the lever on the ratchet down to cut the band:<br />
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<a href="http://2.bp.blogspot.com/-dKBb_2BJM_o/UiNQjGw93jI/AAAAAAAAGWA/dic9U-JcwV0/s1600/20_BeforeCut.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://2.bp.blogspot.com/-dKBb_2BJM_o/UiNQjGw93jI/AAAAAAAAGWA/dic9U-JcwV0/s320/20_BeforeCut.JPG" width="320" /></a></div>
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This strapping will not hold much weight, so I don't recommend it as the only battery support mechanism, but it does keep things in place nicely while assembling packs.</div>
Ross Cunniffhttp://www.blogger.com/profile/06668735330276350432noreply@blogger.com0tag:blogger.com,1999:blog-7194210235180823237.post-50564524785876763722013-09-01T07:30:00.001-07:002013-09-01T09:12:53.493-07:00New Charger Mounted<div dir="ltr" style="text-align: left;" trbidi="on">
Although the old <a href="http://electrojeep.blogspot.com/2008/11/charger-mounted.html">Manzanita Micro</a> charger was very customizable, it had two big drawbacks when considering its use with J1772:<br />
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1. There is no easy way to adjust the amperage automatically<br />
2. It is not isolated, which can lead to ground faults, and possibly even electrocution (!)<br />
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So, I changed the charger. I went with the Evcon HF/PFC2500 charger. The drawback of this charger relative to the Manzanita is that you have to specify its configuration when ordering. Also, the 2500 watt capacity is lower. This is deliberate. Much of the J1772 infrastructure supports a maximum load of roughly 15A (although it can theoretically go as high as 30 or 80 amps). 2500W at 240V fits nicely under this, and the weight and size are convenient. It does mean that a full charge of 22 kWh (70% discharge level of the new 31 kWh pack) will take a while - 9 hours or so at 240V. But this fits easily in an "overnight" charge.<br />
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I mounted the charger somewhat forward of where the old charger was mounted. I first put 1/4" threaded rod in as studs, then replaced the plastic skin on the Jeep, then placed the charger:<br />
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<a href="http://2.bp.blogspot.com/-uDWjBmuXZnA/UiNPR9QMzvI/AAAAAAAAGV0/t5f6whzqiAI/s1600/17_ChargerMounted.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://2.bp.blogspot.com/-uDWjBmuXZnA/UiNPR9QMzvI/AAAAAAAAGV0/t5f6whzqiAI/s320/17_ChargerMounted.JPG" width="320" /></a></div>
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I've also removed all of the old charger support components - there will be new components coming soon...</div>
Ross Cunniffhttp://www.blogger.com/profile/06668735330276350432noreply@blogger.com0tag:blogger.com,1999:blog-7194210235180823237.post-42182821581161054082013-09-01T07:20:00.000-07:002013-09-01T09:14:23.933-07:00Charger Inlet<div dir="ltr" style="text-align: left;" trbidi="on">
Another standard that has emerged is <a href="http://en.wikipedia.org/wiki/SAE_J1772">SAE J1772</a> - a new standard for EV charger plugs. It is safer - it uses pilot and control signals to ensure that there is no current flowing unless an actual EV is connected. It is also becoming more widely available, with companies like ChargePoint providing pay-per-use charging stations. The Jeep will be 1772 compatible. To do this required quite a lot of hacking...<br />
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The inlet was much larger than the previous plug I used, so I had to rip out all of the old metal where the gas filler tube used to be:<br />
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<a href="http://2.bp.blogspot.com/-GXHn0amy2Uo/UiNLuEUyJUI/AAAAAAAAGVE/1CuXrGLuEac/s1600/11_RippingOut.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://2.bp.blogspot.com/-GXHn0amy2Uo/UiNLuEUyJUI/AAAAAAAAGVE/1CuXrGLuEac/s320/11_RippingOut.jpg" width="320" /></a></div>
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I also ultimately removed the remainder of the metal around the base - it was spot-welded in about half a dozen places, so was fairly easy to remove. I then fabricated new sheet metal to replace it - you can see the poster-board template I made on the right:<br />
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<a href="http://3.bp.blogspot.com/-Ft5c0010jkI/UiNLuBJQs4I/AAAAAAAAGVg/Hmkt7bXaE5Q/s1600/12_NewMetal.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://3.bp.blogspot.com/-Ft5c0010jkI/UiNLuBJQs4I/AAAAAAAAGVg/Hmkt7bXaE5Q/s320/12_NewMetal.jpg" width="320" /></a></div>
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Here you can see the new sheet metal test-fit in place. This will also provide more room for components in the rear compartment - the level "base" replaces the complicated angled sheet metal that enclosed the previous gasoline filler (seen in the first picture in <a href="http://electrojeep.blogspot.com/2008/11/charger-mounted.html">this posting</a>):<br />
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<a href="http://1.bp.blogspot.com/-BwOAw_vIJaQ/UiNLuNAFvqI/AAAAAAAAGVA/Xz_LRMWOc5Q/s1600/13_InPlace.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://1.bp.blogspot.com/-BwOAw_vIJaQ/UiNLuNAFvqI/AAAAAAAAGVA/Xz_LRMWOc5Q/s320/13_InPlace.jpg" width="320" /></a></div>
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Here is the view from the outside. This is a nice vertical piece of metal to attach the new inlet to:<br />
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<a href="http://1.bp.blogspot.com/-1ly8JMTHG_8/UiNLuTry3pI/AAAAAAAAGVM/fTObWGRlo7o/s1600/14_FromOutside.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="http://1.bp.blogspot.com/-1ly8JMTHG_8/UiNLuTry3pI/AAAAAAAAGVM/fTObWGRlo7o/s320/14_FromOutside.jpg" width="240" /></a></div>
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I painted it white, put exterior silicone-based adhesive liberally around everything, then riveted it in place:<br />
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<a href="http://2.bp.blogspot.com/-jgMbntcIzS8/UiNLu3S7mbI/AAAAAAAAGVY/ZLhPvNkFnk8/s1600/16_AllDone.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="http://2.bp.blogspot.com/-jgMbntcIzS8/UiNLu3S7mbI/AAAAAAAAGVY/ZLhPvNkFnk8/s320/16_AllDone.jpg" width="240" /></a></div>
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And here is the new J1772 inlet under the gas lid. Very nice, if I do say so myself!</div>
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<a href="http://2.bp.blogspot.com/-7VghEvxFYzA/UiNLuvymSzI/AAAAAAAAGVc/hMntAoTFLC4/s1600/15_J1772.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://2.bp.blogspot.com/-7VghEvxFYzA/UiNLuvymSzI/AAAAAAAAGVc/hMntAoTFLC4/s320/15_J1772.jpg" width="320" /></a></div>
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Ross Cunniffhttp://www.blogger.com/profile/06668735330276350432noreply@blogger.com0tag:blogger.com,1999:blog-7194210235180823237.post-56304506498913991452013-09-01T07:03:00.002-07:002013-09-01T09:14:09.252-07:00Rear HV Terminals<div dir="ltr" style="text-align: left;" trbidi="on">
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As part of the conduit-routing process, I added new holes into the lower rear box. There are three holes. The leftmost is for the upper-rear-to-under-seat conduit; the center one is for the lower-rear-to-front most-positive cable, and the right one is for the front-to-rear most-negative (2 gauge) cable:</div>
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<a href="http://1.bp.blogspot.com/-RuAXr4zgMaE/UiNIRMm55AI/AAAAAAAAGUk/xPgPmS_COp4/s1600/08_HolesDrilled.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://1.bp.blogspot.com/-RuAXr4zgMaE/UiNIRMm55AI/AAAAAAAAGUk/xPgPmS_COp4/s320/08_HolesDrilled.JPG" width="320" /></a></div>
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Here are the conduit ends in place:<br />
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<a href="http://2.bp.blogspot.com/-TDlpdIdKib0/UiNIRMTkcBI/AAAAAAAAGU0/JZ1bWSuM6Js/s1600/09_ConduitEntry.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://2.bp.blogspot.com/-TDlpdIdKib0/UiNIRMTkcBI/AAAAAAAAGU0/JZ1bWSuM6Js/s320/09_ConduitEntry.JPG" width="320" /></a></div>
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And here is the assembly with cables and terminals in place. The terminals are fiberglass, designed for this purpose, and provide a convenient place to connect the cells as well as the charger:<br />
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<a href="http://1.bp.blogspot.com/-Ew8ZGCV6-6w/UiNIRMwtGcI/AAAAAAAAGUo/faquEi_aa3I/s1600/10_Terminals.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://1.bp.blogspot.com/-Ew8ZGCV6-6w/UiNIRMwtGcI/AAAAAAAAGUo/faquEi_aa3I/s320/10_Terminals.JPG" width="320" /></a></div>
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Side note: I've known about step drills for a long time, but this is the first time I'd ever used one (seen in-place in the drill to the lower right). For drilling holes in 1/8" or less steel, it is fantastic - no more changing drill bits from 1/8 to 3/16 to 1/4 to 5/16 to 3/8 for every hole... it "just works" (with a liberal application of cutting oil to help).</div>
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Ross Cunniffhttp://www.blogger.com/profile/06668735330276350432noreply@blogger.com0tag:blogger.com,1999:blog-7194210235180823237.post-56238209709540972392013-09-01T06:54:00.004-07:002013-09-01T09:13:56.933-07:00Orange is the New Black<div dir="ltr" style="text-align: left;" trbidi="on">
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Over the years since I started work on the ElectroJeep, EV standards have evolved which help provide safety for first responders. The most prominent standard is "Orange is High Voltage" - this tells first responders to avoid those areas, and not to cut any orange cables. This standard is why I have gone to orange 2/0 welding cable for most HV wiring. It is also why I tried this:</div>
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<a href="http://4.bp.blogspot.com/-bkdv0U_GJeg/UiNFOMJSydI/AAAAAAAAGTs/JcOlQ8dPg5I/s1600/01_OrangeSnakes.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://4.bp.blogspot.com/-bkdv0U_GJeg/UiNFOMJSydI/AAAAAAAAGTs/JcOlQ8dPg5I/s320/01_OrangeSnakes.JPG" width="320" /></a></div>
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I actually do not recommend this. This is the conduit for routing HV cable under the Jeep. I used Krylon "plastic paint" to spray it orange. Sadly, the paint does not interact well with the conduit - it remained tacky for weeks, probably due to an interaction with the plasticizer which makes the conduit flexible in the first place. This is why the conduit looks so mucked-up in this next picture - it picked up dust, dog hair, grease, and whatever else it touched. But I put it in place nonetheless - dirty orange is better than no orange at all:<br />
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<a href="http://3.bp.blogspot.com/-QmAc4dMjwbk/UiNFOCT-IZI/AAAAAAAAGTo/eDpSX8lh19g/s1600/02_SnakesOnAJeep.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://3.bp.blogspot.com/-QmAc4dMjwbk/UiNFOCT-IZI/AAAAAAAAGTo/eDpSX8lh19g/s320/02_SnakesOnAJeep.JPG" width="320" /></a></div>
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I also painted as many of the battery racks and covers orange as possible. Here is the upper rear rack:<br />
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<a href="http://4.bp.blogspot.com/-5bB1O7s-4xo/UiNFOC0z92I/AAAAAAAAGUY/30UCYf24lM0/s1600/03_OrangeUpperRear.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://4.bp.blogspot.com/-5bB1O7s-4xo/UiNFOC0z92I/AAAAAAAAGUY/30UCYf24lM0/s320/03_OrangeUpperRear.jpg" width="320" /></a></div>
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And here are the box covers. I neglected to photograph the assembly of the upper rear cover (second from bottom in this photo) and under-seat covers (two small rectangles, second from top):<br />
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<a href="http://2.bp.blogspot.com/-5h3uN81pMQc/UiNFOkopu9I/AAAAAAAAGT0/R177yxQRNUU/s1600/04_NewBlack.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="http://2.bp.blogspot.com/-5h3uN81pMQc/UiNFOkopu9I/AAAAAAAAGT0/R177yxQRNUU/s320/04_NewBlack.JPG" width="240" /></a></div>
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Here are the rear covers in place. I'm very happy with how they fit - tight, but not too tight, which means the cells will be very snug and secure (you can also see the new 1/4" polyethylene sides I riveted into the upper rear rack):<br />
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<a href="http://4.bp.blogspot.com/-416iq7oDCfs/UiNFO3ddYRI/AAAAAAAAGT8/bL86UnuLNxw/s1600/05_RearPlaced.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://4.bp.blogspot.com/-416iq7oDCfs/UiNFO3ddYRI/AAAAAAAAGT8/bL86UnuLNxw/s320/05_RearPlaced.JPG" width="320" /></a></div>
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Here is the front cover in place. You may recall that this originally was going to be the bottom of a new rack - but I decided to use the original rack, and flip the box I made, so that the "bottom" became the "top". I added some tabs so mesh with the original threaded rod mounting points in the rack. The cover also bolts to the sides for added security:<br />
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<a href="http://2.bp.blogspot.com/-M7ak1o4fwow/UiNFPALNVuI/AAAAAAAAGUM/Xvr22bcAtps/s1600/06_FrontPlaced.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://2.bp.blogspot.com/-M7ak1o4fwow/UiNFPALNVuI/AAAAAAAAGUM/Xvr22bcAtps/s320/06_FrontPlaced.JPG" width="320" /></a></div>
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Finally, here are the covers for the under-seat boxes. The left and right covers are slightly different, since the boxes are slightly different, which is why they are prominently labelled:<br />
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<a href="http://1.bp.blogspot.com/-STDC7P2O8Es/UiNFPTlSwOI/AAAAAAAAGUI/45EKEu_hqkU/s1600/07_UnderSeatPlaced.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://1.bp.blogspot.com/-STDC7P2O8Es/UiNFPTlSwOI/AAAAAAAAGUI/45EKEu_hqkU/s320/07_UnderSeatPlaced.JPG" width="320" /></a></div>
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Ross Cunniffhttp://www.blogger.com/profile/06668735330276350432noreply@blogger.com0tag:blogger.com,1999:blog-7194210235180823237.post-20436110359714260022013-09-01T06:37:00.000-07:002013-09-01T09:12:53.486-07:00New Rear Cover<div dir="ltr" style="text-align: left;" trbidi="on">
I built the original lower rear rack based on the dimensions of Concorde AGM 1280T batteries. CALB 100AH cells are similar in height - but each cell will have a BMS module on top of it. This means the original rack is just a hair too shallow. To fix this, and to provide more support for the cells, I built a new lower rear rack cover - built out of 1/8" thick steel again:<br />
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<a href="http://2.bp.blogspot.com/-L6Crjr9jc_A/UiNCjehfCSI/AAAAAAAAGTc/9Z2sWeu-c4k/s1600/00_WeldingRack.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://2.bp.blogspot.com/-L6Crjr9jc_A/UiNCjehfCSI/AAAAAAAAGTc/9Z2sWeu-c4k/s320/00_WeldingRack.JPG" width="320" /></a></div>
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The clamps are to hold the top angle iron in place during welding. I used every clamp I own for this... The angle iron adds significant stiffness to the rack, without adding a lot of weight. You can also see the tabs which will be used to bolt the top in place. This new top adds about 7/8 of an inch of extra clearance - just enough.</div>
Ross Cunniffhttp://www.blogger.com/profile/06668735330276350432noreply@blogger.com0tag:blogger.com,1999:blog-7194210235180823237.post-40498961566373914642013-09-01T06:25:00.005-07:002013-09-01T09:12:53.488-07:00Top-Balancing the Pack<div dir="ltr" style="text-align: left;" trbidi="on">
I did not do exactly "nothing" on the Jeep over the year. In May/June I top-balanced the pack. Balancing and monitoring of lithium battery packs is a hotly debated topic in DIY electric vehicle circles. There are those who advocate what is called "bottom balancing" - discharge all the cells to a given voltage level (frequently, 2.7V) and then charge the whole pack in series until the first cell hits a "full" voltage level (often, 3.5V or 3.6V). You record the overall pack voltage at this point, which becomes the "full" point. Not all the cells are full, but they theoretically will discharge to the same low point, which is why this is called bottom balancing. Bottom balancing advocates say that they can run safely without a battery monitoring system - they check the cell voltages occasionally - but really that just means that the *owner* has become the BMS.<br />
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Top balancing, as you might imagine, is the opposite of bottom balancing. All of the cells are charged to the same "full" voltage level, and then monitored to make sure that no cell either goes too low during discharge, or too high during recharge. With 96 cells, this requires automated assistance - the BMS. In my case, I'm using the <a href="http://www.cleanpowerauto.com/MiniBMS.html">MiniBMS</a> from Clean Power Auto. It is simple, relatively inexpensive, and conceptually robust. But it will work much better if the cells are all fully charged to the same level before hooking everything up.<br />
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To do this, I used a 25A nominal battery charger, with an adjustable voltage level. Although the battery manual suggests that "full" is when the charge level hits 3.6V, I chose 3.5V to give a slight margin of error. There are almost no amp-hours between 3.5V and 3.6V. I hooked four cells up in parallel to charge - this fit well with my schedule, since it took about 18-20 hours or so for this 400AH megacell to fully charge, and I could just go out every morning and swap out the cells. This went on for 96/4 = 24 days. Here is one example, showing the target voltage set to 3.5V, and the charger putting out 13.7 amps:<br />
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<a href="http://4.bp.blogspot.com/-tf2DxPPXeZ0/UiM_N9_V8qI/AAAAAAAAGTE/B7La7moKTfU/s1600/CellsCharging.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://4.bp.blogspot.com/-tf2DxPPXeZ0/UiM_N9_V8qI/AAAAAAAAGTE/B7La7moKTfU/s320/CellsCharging.jpg" width="320" /></a></div>
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The cells you see cropped to the right of the picture are from another project - the Toad Car - which I used in the 2013 St. Patrick's Day Parade in Fort Collins. I used it to get some experience with lithium cells, and with the MiniBMS. Those are 40AH cells, paralleled to get 80AH, and then put in series to get 25.6 volts. Here is the Toad Car in the parade:<br />
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<a href="http://3.bp.blogspot.com/-qBlr9OwWrX4/UiNAIjaBM4I/AAAAAAAAGTQ/6R2HRZe9CJ4/s1600/RossToadCar.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="http://3.bp.blogspot.com/-qBlr9OwWrX4/UiNAIjaBM4I/AAAAAAAAGTQ/6R2HRZe9CJ4/s320/RossToadCar.jpg" width="240" /></a></div>
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The Toad Car, and the City Council race, were another huge time investment which delayed resumption of work on the ElectroJeep.</div>
Ross Cunniffhttp://www.blogger.com/profile/06668735330276350432noreply@blogger.com0tag:blogger.com,1999:blog-7194210235180823237.post-84204112064512249332013-09-01T06:07:00.002-07:002013-09-01T09:12:53.499-07:00Building the New Front Box<div dir="ltr" style="text-align: left;" trbidi="on">
I'm catching up on a posting backlog dating back over a year. It all started on the 4th of July weekend 2012 with removing the old batteries:<br />
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<a href="http://1.bp.blogspot.com/-VN4VMbJcuig/UiM5rSrAtAI/AAAAAAAAGSM/tj0dIUF9S_Y/s1600/01_OldBatteries.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://1.bp.blogspot.com/-VN4VMbJcuig/UiM5rSrAtAI/AAAAAAAAGSM/tj0dIUF9S_Y/s320/01_OldBatteries.JPG" width="320" /></a></div>
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I also pulled all of the racks and cabling, since I'll be replacing the cabling (with orange high-flex 2/0 gauge welding cable), and refurbishing or replacing the racks:</div>
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<a href="http://4.bp.blogspot.com/-ep20uqNjaGA/UiM5qn6LRMI/AAAAAAAAGR4/wD8X5a7Lvg8/s1600/02_OldRacks.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="http://4.bp.blogspot.com/-ep20uqNjaGA/UiM5qn6LRMI/AAAAAAAAGR4/wD8X5a7Lvg8/s320/02_OldRacks.JPG" width="240" /></a></div>
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Next, I built the front box. It holds 30 cells, and fits inside the <a href="http://electrojeep.blogspot.com/2008/08/front-rack-part-ii.html">original front rack:</a><br />
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<a href="http://1.bp.blogspot.com/-25eqx_rtw8s/UiM5qulb0sI/AAAAAAAAGR0/KlqILDaIsiw/s1600/03_CellsFrontRack.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://1.bp.blogspot.com/-25eqx_rtw8s/UiM5qulb0sI/AAAAAAAAGR0/KlqILDaIsiw/s320/03_CellsFrontRack.JPG" width="320" /></a></div>
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I welded a new front upper rack. Because lithium cells are lighter, I used 1/8" thick steel rather than the 3/16" of the old lead-acid racks and boxes. I originally was going to replace the front rack, so I built a new rack for the bottom. I decided later to just use the existing front rack, and flip the whole rack so that the "bottom" becomes the top - this will be detailed in a later post. Here is the completed rack:<br />
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<a href="http://3.bp.blogspot.com/-a3DuRznFUxo/UiM5seZKUTI/AAAAAAAAGSg/65l0c96RaJ0/s1600/08_BoxWelded.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em; text-align: center;"><img border="0" height="240" src="http://3.bp.blogspot.com/-a3DuRznFUxo/UiM5seZKUTI/AAAAAAAAGSg/65l0c96RaJ0/s320/08_BoxWelded.JPG" width="320" /></a></div>
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I then created the battery box box from polyethylene, 1/4", natural color. I started by cutting a single piece which covers the bottom, front, and back of the box. The piece is then "V" grooved so it folds. This starts with marking the path where the groove should go, and then clamping guides for a router to cut the path:<br />
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<a href="http://4.bp.blogspot.com/-6b3vtuYL0XY/UiM5rAjXXLI/AAAAAAAAGSA/Py2x5WsNs4s/s1600/04_GrooveMark.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://4.bp.blogspot.com/-6b3vtuYL0XY/UiM5rAjXXLI/AAAAAAAAGSA/Py2x5WsNs4s/s320/04_GrooveMark.JPG" width="320" /></a></div>
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Here is the router, showing the "V" groove bit in place:<br />
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<a href="http://2.bp.blogspot.com/-sA5Dea5VCuY/UiM5rM2TtzI/AAAAAAAAGS0/hceT3UneyoE/s1600/05_RouterBit.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://2.bp.blogspot.com/-sA5Dea5VCuY/UiM5rM2TtzI/AAAAAAAAGS0/hceT3UneyoE/s320/05_RouterBit.JPG" width="320" /></a></div>
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With the correct bit depth (not quite all the way through the plastic), it is a simple matter then to run the router between the guides, creating a nice straight groove:<br />
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<a href="http://4.bp.blogspot.com/-ROCkv7ijJ_0/UiM5roQIqOI/AAAAAAAAGSQ/0Wqlzq0hlbA/s1600/06_GrooveCut.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://4.bp.blogspot.com/-ROCkv7ijJ_0/UiM5roQIqOI/AAAAAAAAGSQ/0Wqlzq0hlbA/s320/06_GrooveCut.JPG" width="320" /></a></div>
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Here is a test fit of the rack on the box, to make sure it fits:<br />
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<a href="http://1.bp.blogspot.com/-4BtLWsdke_c/UiM5sJnNTeI/AAAAAAAAGSY/NG2qCLeDQP0/s1600/07_TopFits.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://1.bp.blogspot.com/-4BtLWsdke_c/UiM5sJnNTeI/AAAAAAAAGSY/NG2qCLeDQP0/s320/07_TopFits.JPG" width="320" /></a></div>
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And here is a test-fit of the cells. I was originally going to use threaded rod to retain the cells in place, but it turned out to be impossible to get the rod through the sides when the rack and batteries are in place. But the test-fit was with the threaded rod:</div>
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<a href="http://1.bp.blogspot.com/-nAM0M0w5mCk/UiM5spGhl9I/AAAAAAAAGSo/2N0WX_UDcR8/s1600/09_TestFit.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://1.bp.blogspot.com/-nAM0M0w5mCk/UiM5spGhl9I/AAAAAAAAGSo/2N0WX_UDcR8/s320/09_TestFit.JPG" width="320" /></a></div>
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And that's what I got done on that weekend. I also threw my back out as a result (what a drag it is getting old) which put a crimp (heh-heh) on further progress for over a year...</div>
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Ross Cunniffhttp://www.blogger.com/profile/06668735330276350432noreply@blogger.com0tag:blogger.com,1999:blog-7194210235180823237.post-47767163566928744742013-07-25T07:34:00.001-07:002013-09-01T09:12:53.491-07:00New battery layout<div dir="ltr" style="text-align: left;" trbidi="on">
In the past few months, although I have not done a lot of building on the Jeep, I've done a lot of thinking. I've figured out the exact battery layout I need - using the existing racks. Here is the schematic layout:<br />
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<a href="http://1.bp.blogspot.com/-odEiF25zUW0/UfE2kKYcvYI/AAAAAAAAGP0/j15gR96ERzs/s1600/ElectroJeepLithiumLayout.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="194" src="http://1.bp.blogspot.com/-odEiF25zUW0/UfE2kKYcvYI/AAAAAAAAGP0/j15gR96ERzs/s320/ElectroJeepLithiumLayout.jpg" width="320" /></a></div>
There are 30 cells in the front rack, 3 in each of the under-seat boxes, 26 in the upper rear, and 34 in the lower rear. This totals 96 cells - a little less than the 98 I was originally going for, but not enough to make a significant difference.<br />
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The front box sits in the original front rack, with some room to spare:<br />
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<a href="http://4.bp.blogspot.com/-D2F0RdKzdRg/UfE21PSc09I/AAAAAAAAGQI/8Mhx3UGzzaE/s1600/FrontRackLithium.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://4.bp.blogspot.com/-D2F0RdKzdRg/UfE21PSc09I/AAAAAAAAGQI/8Mhx3UGzzaE/s320/FrontRackLithium.jpg" width="320" /></a></div>
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The lower rear rack is nearly filled with its 34 cells. It will need some plastic inserts to retain the batteries in their positions:<br />
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<a href="http://3.bp.blogspot.com/-mmqD31UnmHg/UfE21NjtqfI/AAAAAAAAGQA/gM7JXB2eYw8/s1600/LowerRearLithium34.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://3.bp.blogspot.com/-mmqD31UnmHg/UfE21NjtqfI/AAAAAAAAGQA/gM7JXB2eYw8/s320/LowerRearLithium34.jpg" width="320" /></a></div>
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Under each rear seat, there is not enough room to put the BMS on top, so it goes on a separate plastic insert/retainer on the side:<br />
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<a href="http://3.bp.blogspot.com/-ew-fw4-EduI/UfE21JEo44I/AAAAAAAAGP8/6kV65WtHCOU/s1600/UnderSeatLithium3.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://3.bp.blogspot.com/-ew-fw4-EduI/UfE21JEo44I/AAAAAAAAGP8/6kV65WtHCOU/s320/UnderSeatLithium3.jpg" width="320" /></a></div>
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And the upper rear rack's 26 cells fit in the original rear rack with room to spare - which will allow for some extra components, such as a mid-pack fuse, the BMS controller, the amp-hour counter/sender. It will also allow all cabling to be inside the boxes, which will eliminate high-voltage cabling from inside the passenger compartment:<br />
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<a href="http://1.bp.blogspot.com/-GcNNdroy7-k/UfE213iKIPI/AAAAAAAAGQU/1pEMniIB73w/s1600/UpperRearLithium26.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="http://1.bp.blogspot.com/-GcNNdroy7-k/UfE213iKIPI/AAAAAAAAGQU/1pEMniIB73w/s320/UpperRearLithium26.jpg" width="320" /></a></div>
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Ross Cunniffhttp://www.blogger.com/profile/06668735330276350432noreply@blogger.com0tag:blogger.com,1999:blog-7194210235180823237.post-1580247909440003932013-07-25T06:46:00.002-07:002013-09-01T09:12:53.484-07:00Back at it<div dir="ltr" style="text-align: left;" trbidi="on">
I've been busy with <a href="http://www.ross4council.com/">other</a> <a href="http://www.fcgov.com/council/members/?district=5">things</a> over the past year, but now I have a couple of weeks - and I think I can get the Jeep back on the road with its new LiFePO4 pack in that time.<br />
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I've created a Google Docs Spreadsheet of the to-do items - you can see it <a href="https://docs.google.com/spreadsheet/ccc?key=0AmEAnFW4wCP7dENsQWJ5eGZYQ0FTTW5PUGw0MDNCQWc&usp=sharing">here </a>and follow progress. I'll also try to blog what I've done in the meantime, but the focus will be on completion not documentation.</div>
Ross Cunniffhttp://www.blogger.com/profile/06668735330276350432noreply@blogger.com0