Engine Be Gone!

My daughter KatC and I pulled the engine from the Jeep today. First, you've got to disconnect *everything* from the engine. Here I am, playing one of my least favorite games, "where the heck is that last bolt hiding?"


Once everything was disconnected, we pulled the engine forward to clear it from the transmission main shaft. I'm pulling (using my, ahem, substantial body weight) and KatC is using a pry bar to help separate the engine from the bell housing:


Here it is, free from the transmission and being lifted out of the engine bay. KatC is doing the hydraulic lift work. Her friend Brad came by and helped observe our careful attention to safety procedures:


Finally, it's free - here is KatC, posing beside the engine (dangling precariously - I lowered it down right after this was taken):


Here is the gaping hole it left. Much to do here - tomorrow's activity will be to give it a thorough cleaning:


This was actually the main point of the exercise - I need access to the flywheel so that I can send a rubbing to ElectroAuto of the center 6 bolt holes so they can make sure the adapter they are making for me will actually fit. I'm guessing the red gunk is clutch dust - I was very careful not to blow it around, it's likely to be toxic:


And here is the rubbing I'll be sending to ElectroAuto. Theoretically, they could take measurements from this 200 DPI scan, but I'll give them the original just to be safe:

Designing Front Racks

After fiddling with things some more, deciding to go with AGM batteries, and looking at how Nick at DriveEV lowered his rear battery box, I changed how I'm planning on placing the batteries. The 9 batteries in the rear trunk will be lowered so the top of the box is even with the floor. This gives a much lower center of gravity. There will be 3 additional batteries in the back, lying on their side (because they will be AGM, this won't be a problem). This also keeps the COG as low as possible. I can't sink these three into the floor because there is a structural cross-member right below that in the rear trunk.

The front batteries are completely reconfigured. Since I decided to go AGM, I don't have to worry about accessibility for watering the batteries, which allows a more 3-dimensional design. You can see how 4 of the batteries are on side racks down low, another is way down below the DMOC controller, and 5 more are in a rack above the motor. This gets 10 batteries into the front trunk, which will balance much better with the 12 in the rear (versus 8::14 as it was split in the previous design).

With the placement of the batteries pretty much as I want it, I also designed how the front racks will work. The green components below are intended to be 2" steel box tubing. The rearmost two crossmembers will support the motor - that's why they are cut & rewelded into that shape - it allows the motor to be slightly lower than the engine bay, so it can line up better with the transmission. The racks for the lower 5 batteries (purple-ish) rest directly on this box tubing. And then the upper battery rack (orange) rests on 4 2" box tubing uprights. And the rack for the controller (pink) sits on top of two more box uprights.


In other news, Electro Auto says they *do* have a pattern for an AC55 motor adaptor for the Jeep Cherokee, so I have ordered one from them. If something does not work out, I can always fall back on my original plan.

Christmas in March

Over the past few weeks, quite a few parts that I've ordered have drifted in. From Quadratec, comes a variety of Jeep upgrades. First, a 2" Old Man Emu heavy load lift kit (shocks, coils, leaf springs, HW):


Second, a front brake overhaul kit (rotors, pads, HW):


Third, a rear brake drum-to-disc conversion kit (I'm not 100% certain this will fit the axle on my Jeep; if not, I'll upgrade the axle):


And fourth, a kit to convert the vacuum-actuated 4WD transfer case into a manual cable-controlled one:


Here are cable, connectors, and tools from Cloud Electric:


A vacuum pump kit (to operate the power brakes) from EV Source:


An electric power steering pump kit from Canadian Electric Vehicles:


Two 400V, 1000W ceramic heaters from Mor Electric / Infrared Heaters:


A PakTrakr, 5 remotes, a current sensor, and a computer interface (not shown):


And, finally, a complete workshop repair manual for my Jeep (including full electric diagrams) from Auto Books Bishko:


I have deliberately spread the orders around to a variety of EV parts providers. This is for three reasons: first, it limits the risk of any one of them completely messing up the build schedule. Second, it allows me to do my part to keep EV suppliers in business. Finally, it allows me to give feedback to people on their service and quality. So far, all of the suppliers I've dealt with have been prompt and responsive - no complaints from me!

I've contacted a local garage to install the lift kit and brakes - I don't think my skills add any value there. But everything else me and my wife and daughter will do ourselves!

Flywheel Mounting, Part 2

After much discussion, and lots of doodles, I think I have my final answer. The various factors which contributed to this include:

• I definitely want to use the original manual transmission (it will feel too sluggish otherwise)
• EA does not have a prefab kit for the Jeep
• I like having the splines meshing with the hub
• I want to minimize holes
• The splined hub must allow the compression effect of the taperlock
  
• Machining should be as simple as possible

So, I came up with this idea. Basically, the splined hub gets machined down slightly to a shape like two truncated cones stuck together base-to-base and then cut into 4 segments:


Next, I create two nearly identical outer hubs, 4 inches in diameter - the six holes are intended to match the bolt locations on the flywheel itself. The center hole is slightly tapered to match the newly machined hub. The bottom of the two hubs is threaded to accept the bolts (that's the only difference between the bottom and top hubs). And that's it:


The inner and outer hubs mate like this. The unthreaded top part goes next to the flywheel, the threaded bottom part goes on the other side, and the flywheel bolts hold the whole thing together. The assembly plan is to position and torque down the hub without the flywheel attached at first. The compression / friction caused by torquing it all together should hold it in place when the bolts are removed. And then the flywheel is put on and torqued to the proper specifications.


A PDF version of all these is available here. One last note: I did a calculation, and I believe that the hub will compress properly if cut into four segments this way. Calculations (based on the angle of the splined hub facets) show that the direction of compression will be offset about 3 degrees from directly toward the center of the shaft. I don't believe this will cause any issues.

Comments and suggestions welcome...

Flywheel Mounting, Part 1

While waiting for various parts to show up, I've been thinking about the problem of mounting the flywheel to the motor shaft. Azure Dynamics helpfully points out that the splined shaft has a matching hub, available from Hub City, part number 0332-00034. I found it in their online catalog:


After finding a local retailer who carries and special order Hub City parts, I found myself the proud owner of two of them (one as a spare). Here is one, in person:


It will go onto the motor shaft. Here it is, next to the shaft, for scale:


Here is a test fitting on the shaft - it fits *very* well - it takes a fair amount of steady force to remove it after sliding it on gently:


The plan is to find a local machine shop who can turn this into a taperlock hub. Just as in the Electro Auto kit, the idea behind a taperlock is to have a tapered hub that fits into a conical opening in a larger plate, and then the compression of the two with 5 screws also compresses the hub around the shaft. It is going to be tricky with the splined hub, since the splines will tend to resist compression. Here is a first pass drawing of how the hub will be modified:

I need to think about it some more - specifically:

• Will the two cuts allow the hub to compress sufficiently against the splines?
• Should the cuts be partially through the front of the hub (as shown), or through the back of the hub (with the uncut part machined smaller yet), or would a single cut yield better results?

Maybe once I find a good local machinist they can help me answer some of these questions.

One other option rather than turning the hub into a taperlock is to tap a center hole in the shaft, and then use a center bolt on a machined plate to keep the hub in place. The drawbacks are that any torque opposite the thread direction will tend to make the bolt want to come out. It is possible that the splines will prevent this (especially if the machined plate is also bolted directly to the hub, in addition to the shaft). But the possibility concerns me, since with regen braking, torque is applied in both CW and CCW directions on the flywheel.

Christmas in February

The shipment from Azure Dynamics arrived today. It was all attached firmly to a pallet and plastic wrap / strapped together. The total package weight was 330 lbs:


Here it is, all unboxed / unpacked sitting on the driveway:


I ordered the AC55 motor (weight: 106 kg / 233 lbs):


...a DMOC445 controller (same as in the Volt914):


A 312-V DC-DC converter designed to work with a backing battery:


And the interface kit, composed of this cool switch (which controls motor direction & power as well as regen braking and, just for fun, the electric heater):


...and this regen braking relay & wiring:


...and a throttle potbox & wiring:


...and the main wiring harness to the DMOC445:


...and various and sundry misc connectors, etc. for the above:


So, off to order the rest of the stuff. There are some basic upgrades to the Jeep:

• Front disc brake replacement
• Rear disc brake upgrade
• Suspension upgrade (a 3-inch "heavy-duty" lift kit)
• Cable switch to replace 2wd->4wd vacuum switch
  

As well as a long list of parts for the conversion:

• 2/0 or 4/0 welding cable for high-current wiring
• Charger
• (maybe) 26 battery charging regulators (if I go with AGM)
• 26 batteries (AGM or flooded)
• Cable lug ends
• Heater core
• Power steering pump electric feed
• Power brake system vacuum system
• Lots of L-bar and square tubing to weld together for various supports
• Material for battery boxes (possibly plywood, still debating)
• Gauges, shuts, and such
• Fuses & circuit breakers
  
• Connectors, nuts, bolts, grommets, kitchen sinks, etc.
  

The Jeep upgrades are on order. Still evaluating the rest.

Parts on the way, and motor notes

I got notification from Azure Dynamics that my controller, motor, DC-DC converter, and interface harness have shipped. They should arrive in Colorado tomorrow. I'll put pictures up when they get here; in the meantime, here are some notes on why I selected the motor I did.

Basically, a sports car (like the volt914) is designed with a gearing ratio that encourages higher RPM. A SUV, like the ElectroJeep, is heavier, and the tranny typically has a lower gearing ratio. So, I was looking for low-RPM torque, and not too concerned with high-RPM perf. Here is a chart I made that combined two charts from Azure (along with an estimated "AC24L" motor that TimK mentions in this post on his 914ev blog). This plots torque vs. RPM. Note the *much* higher torque at low RPM, but the lower torque at higher RPM. The crossover happens roughly at 3000-3500 RPM. Edit - I added data for the Advanced DC 9" motor for comparison purposes:



Most people are accustomed to thinking of motor performance in horsepower, so here is the same data recalucated for HP:


I think this chart illustrates well why the AC55 is suitable for truck / SUV applications, whereas the AC24 is much better for smaller, sporty cars. This higher torque / HP is going to be especially important for the Jeep, since its curb weight is 50% higher than the Porsche, and its battery weight will similarly be 50% higher.

Time to look into 4-wheel disc brakes...