Wednesday, July 1, 2009

Full Sketchup model, updated

I have updated the full Sketchup model of the ElectroJeep and uploaded it to the Google 3D Warehouse. You can play with this preview image if you don't want to download Sketchup:

Click the "3D" button in the middle of the picture. You can then click the model and move the mouse left and right to rotate the view.

Saturday, June 27, 2009


Today I finally got around to fixing the sagging rear end. Although I had added a lift kit, the weight of 950 pounds of batteries in the rear end was just a bit too much for them. After thinking about it for a while, I decided to get an additional Old Man Emu leaf spring to insert into the pack.

The first step, of course, is the same as the original lift - remove the old springs. Jack up the Jeep and add heavy-duty jack stands. Also, put jack stands under the rear axle. Unbolt the shock from one side, let the axle droop (being careful to avoid breaking flexible lines), and then unbolt and remove the leaf springs, with a liberal application of elbow grease.

Here are the springs next to the add-a-leaf. The new leaf is nearly as long as the whole pack, designed to support the main spring. The "pointy" end goes on the rear, where the shackle attachment is. The "blunter" end goes toward the front:

To prevent sudden explosive unspringing of the pack, I clamped it and then unbolted the center bolt. I then gradually unscrewed the clamps, allowing the leafs to separate:

And here is the pack disassembled. The add-a-leaf is shown placed between the main leaf on the left and the rest of the pack on the right:

Assembly, as they say, is the reverse of disassembly. Before assembly, though, I applied liberal amounts of grease to the new leaf. To keep the leafs aligned I inserted a screwdriver in the bolt hole, and then clamped down. When it was clamped down tight, I removed the screwdriver and replaced the bolt. I then alternated clamping down even tighter, and tightening the bolt:

And then, I replaced the leafs on the Jeep. This went a lot easier than last time - not sure if I'm better at it, or if the year of sitting on them has made the leaf pack "remember" the approximate distance between the front and rear eye:

And here is ElectroJeep, all happy and level with its new add-a-leaf. It rides very nicely, now, too!

Edit (Jul 31 2009)

By request, here is what the Electrojeep looked like before the add-a-leaf (this photo is from a post in January). It actually got a bit worse after this - I added 1.5" spacers to the front springs to get more clearance above the front differential. Unfortunately, I don't have any pictures of the whole Jeep at that point.

Friday, June 26, 2009

Gauges, and legal to drive!

Over the past week, I've squeezed some 12V wiring work into odd moments here in there. This all culminated in getting the dashboard gauges (mostly) in place. It all started with the main cluster. Before putting it into place, I needed to splice connections into this connector, which fits into the gauge cluster to make the lights work:

The connections on this connector are as follows:

Gnd -+ 1 | 18 +- Illum
Left Turn -+ 2 | 17 +- Hi Beams
n/c -+ 3 | 16 +- Right Turn
Gas A -+ 4 | 15 +- Keyed +12
Oil -+ 5 | 14 +- Gnd
Gas C -+ 6 | 13 +- Illum
Illum -+ 7 | 12 +- Batt
Gas Tank? -+ 8 | 11 +- Water
Gas Tank -+ 9 | 10 +- Illum

I spliced in connections for the new gauge lights (the red and black cables - into wires on pin 1 and 18), and a connection for the gas tank light, which will light up when the Jeep is plugged into the wall and the key is turned on (i.e. - don't drive away you idiot!):

I then hooked in a 3-way wye into each of the illumination splices (there are three new gauges):

I also pulled all the wiring through the bulkhead into the gauge area. It made quite a spaghetti mess. Note the circular "thingy" toward the left side (inside the oval hole in the white surface). That is the original mechanical speedometer cable. It was the source of much, umm, "amusement" down below...

Underneath, I needed a good source of keyed +12V. Turns out this orange wire is keyed, and normally drives power door locks and power windows. I have neither, so this wire is actually very under-used. So I spliced into it for the brake relay and 312V ammeter:

Back in the engine compartment, I made looms out of the control wires, and put flexi-guard around them:

I removed the original bulkhead grommet, and enlarged the hole so all the wires could pass through it. Removing the grommet was highly entertaining, as it apparently was molded into place on the original wiring harness... but with enough cutting & hacking & cursing, I got it out and modified:

And here it is back in place, with a generous dollop of silicone sealer around everything. I also added sealer to the original hole where the throttle cable had gone (the square hole toward the lower right):

Back in the cabin, I neatened the spaghetti explosion into a loom and added flexiguard here too. This is especially important to protect those 312V wires that control the volt meter - although they are fused, I hate to risk more damage than necessary:

And here is the gauge cluster snapped into place. This was actually a *lot* more work than it sounds. It was a real pain to get the gauge cluster electrical connectors plugged in - despite the loom organization, the longer 16 AWG wires kept getting in the way. And then, the speedo cable was a *real* royal pain to get back into place. I finally found that unscrewing a mounting screw down under the engine gave me enough slack that I could pull the cable forward and get it to snap into place. It took me 15 seconds to type that. It took me 2 hours to figure that out and do it:

I then put the cluster face on, along with the 12V ammeter and 12V voltmeter. Here is everything plugged in and lit up. Note the ammeter showing about 40A - that's power steering plus power brake pump plus headlights plus turn signal plus brake light. Not too shabby. The DC-DC converter puts out 55A. I should almost never tap into the aux battery:

With all that in place, the ElectroJeep is now fairly road-worthy. So I took it on the road. I took it down to our local Jeep dealer and had a VIN verification done. I then took the paperwork down to our local county courthouse DMV, and got the Jeep retitled as Electric! Note the circled "FUEL E" designation. Unfortunately, they will mail me the actual title, so I don't have an image here, so the registration will have to do:

And here is the license plate with its new registration tags - all ready to drive legally on the roads!

One more note - I drove it about 11.6 miles round-trip to get the VIN verification done. It took roughly 4.6 KWh to recharge the batteries after I got home. This translates to 400 watt hours per mile from the wall - which compares pretty favorably with 379 watt-hours per mile for the volt914. Of course, I was driving 25-30 MPH the whole time, but I do not have the regen braking hooked up yet. So 400 is probably the right number. This translates to a range of roughly 50 miles at 80% DOD. We shall see...

Sunday, June 21, 2009

Misc Wiring

I also spent some time doing more wiring cleanup on the 12V system. I removed the molding from the driver's side doorways and routed the PakTrakr cable from front to back under it:

I also found the brake light wire (the blue wire with the black stripe):

I crimped a connector on so the regen brakes will light the brake lights when I enable them:

I did a little more under-hood wiring cleanup, but no pix yet. Working toward getting the dashboard restored...

Zener Diode Battery Regulators

I got tired of worrying about the balance of my batteries. I had been charging them individually - I'd tried a bulk charge once but it overcharged several batteries. I think I even caught a whiff of hydrogen sulfide - if so, it means one or more of the batteries outgassed. Very bad for sealed batteries.

So, while I wait for a more advanced BMS, I decided to build some Zener Diode battery regulators. I found a very nice writeup here (PDF instructions here) and followed it fairly closely.

First, you start with the components - from the left, they are:
  • 10 Ohm 1W resistors
  • 5/16" ring terminals
  • 6.8V 5W zener diodes
  • 1/2A miniature light bulbs

I soldered the resistors to the light bulbs:

I then soldered half of the zener diodes to ring terminals, making the positive terminal (the stripe goes toward the terminal for the positive terminal):

I then soldered the light bulb / resistor assembly to the diode / terminal assembly. Three of them have a wire in between due to physical layout issues with the rear battery rack:

I soldered the other half of the zener diodes to the negative terminals - the silver band goes *away* from the negative terminal:

And then I soldered a 16 AWG wire in between the positive and negative terminals, heat-shrink wrapping the ends for added strength:

And here are all 26 zener diode battery regulators. 9 of them got an epoxy / potting treatment (they are the ones that live in the front compartment, they need to be a little more water tight than the rest):

Here you see the regulators on the front rack:

And here they are on the rear rack. Note the three regulators on the batteries closest to you - these are the ones which I put extended length wires on so you could actually see them (otherwise, they would be hidden by the lip of the rear compartment):

With all the regulators in place, time to test them. I connected the CamLok pack disconnects, hooked up the charger, plugged it in, turned it on, and... light! I had previously charged the lower rear rack batteries, so the lights came on immediately:

The idea behind the light is that when the lights are on you should reduce the charging current. This was with a 5A charge current - pretty low - but until I get a more automatic system, what this means is that I will have to go watch the lights and turn the amps down on the charger manually when they start to come on.

The one thing I note is that having the regulators makes monitoring the individual battery charges with the PakTrakr kind of wacky. Sometimes the batteries would register very low (i.e. 8.6 volts). This effect goes away when the batteries are not charging - I suspect the extra shunt action between the positive and negative battery terminals confuses the poor PakTrakr.

All in all, a very successful week of work. I estimate that each regulator took about 20 minutes (there were 9 solder joints on each one), so this is about 10 or so hours of work all told.

Thursday, June 18, 2009

ElectroJeep - A Summary

This is a summary of the ElectroJeep project. Although the project is not 100% complete, it is close enough to document. I will update this posting as the last few items get done.

The project started in January of 2008, with the donor vehicle - a 1988 Jeep Cherokee XJ:

I decided to go with Azure Dynamics' AC55/DMOC445 motor/controller combination, along with various interfaces which they provide:

The first step in any conversion is removing the Internal Combustion Engine. This typically requires an engine hoist and lots of elbow grease (and lots of real grease, too):

I also decided to go with lead-acid batteries. The weight this adds requires an upgrade to the suspension, so I purchased a heavy-duty lift kit (Old Man Emu):

Here is the front installed, along with a 1.5" lift block to provide enough clearance between the motor and the front differential:

Here is the rear installed. Yet to be done - I need to install an Add-A-Leaf kit to compensate for sagging in the rear:

Here is the Jeep with the lift installed and with essentially no weight inside - it makes it look like it will ride very high. This is an illusion. Once I add 500 pounds of motor, transmission, and battery racks, along with 1500 pounds of batteries, it will ride very close to where it started.

The motor is mated to the original transmission via a custom-built profile plate and hub from Electro Automotive. Here, my daughter KatC torques the bolts to spec:

Here is the motor mated to the transmission. Note that in the final design, the motor is actually rotated 180 degrees upside-down from what is shown here:

The motor is mounted via a cradle system which attaches to the original motor mounting points:

Thus. Here you can see that the motor is in fact "upside-down" to provide maximum clearance above the differential along with adequate spacing below the front battery rack:

The batteries themselves are sealed 12V Group 24 AGM batteries - the Concorde Chairman AGM 1280T. They weigh 55 pounds each, and are spec'd to 80 amp-hours of juice:

I designed racks to hold the batteries and welded them from 3/16" angle stock. Here is the front rack, which holds 8 batteries:

This is the rear rack, which also holds 8 batteries:

This layout is required because this rack is sunk beneath the floor of the rear cargo space, and I need to avoid cutting structural members:

This is a third rack, the Upper Rear Battery Rack, which holds 7 batteries:

Under the rear seat are two batteries in individual racks:

Here you can see one of the racks welded into place:

The last battery is mounted in the front compartment in the same orientation as the original 12V battery, but on the driver's side. There is also a 27th 12V battery in the original battery location which provides power for all the 12V systems in the Jeep.

The batteries are interconnected with 4/0 gauge welding cable. Where it is exposed to possible damage, it is armored by plastic conduit:

The batteries in a rack are interconnected with copper straps. There are three 1/16" by 1" straps connecting each battery, which provides close to the same (low) resistance as 4/0 welding cable. The straps are bent to provide some degree of flexure to avoid levering the bolts out of the battery threads:

A variety of electronic components needed to be added. Here are some high-voltage fuses and a high-voltage relay:

Also, various 12V systems needed to be changed. Here are a circuit breaker and relay for the new electric power steering pump (see below):

This box contains several relays which interlock various systems. These relays do things like inform the controller that the system is plugged into the wall (so that you can't drive off when plugged in), they control the 300+V heater current, and they also control the DC-DC converter (see below):

In the rear, the charger is mounted. This charger can do the bulk charge of the full 312V string of batteries (the charge voltage is 372 volts!):

The charger connects to an inlet placed in the original gas tank filler location:

Various components in the front (power steering pump, controller, DC-DC converter) also required custom welding of racks:

Here is the electric power steering pump mounted and hooked up:

And here is the power brake vacuum pump and reservoir (note that the rat's nest of wiring has been cleaned up since this photo was taken!):

Here is the DC-DC converter in place. You can also see the 12V accessory battery. The 26th traction battery is mounted in the same orientation on the driver's side:

Also, the heating system was changed to electric. Two 400V 1000W ceramic heating elements were ganged together and placed in a custom box inside the heater box:

The throttle now operates a potentiometer in this "pot-box":

And the gauges have been upgraded to show various information necessary to run an electric vehicle. Shown here are the high-voltage volt meter (in the former gas gauge), along with new 12V amp and volt meters. Not shown are the 200A traction battery amp meter nor the PakTrakr battery monitoring system:

And that's where it stands. The vehicle is operational, mostly, but not yet street legal nor registered with the State. As I said, I will update this posting when the final bits-and-pieces are complete, so watch this space...