Wednesday, April 8, 2009


I was down at the shop today, and they mentioned that the coupling was cut and ready for a test fit on the motor shaft. Later, I received these pictures of the coupling and flywheel mounted. Every day, in every way, I'm getting closer and closer.

Tuesday, April 7, 2009

Battery Selection

I finally made a decision on batteries. I'm going to go with 12 Enersys Odyssey AGM 12V, 100Ah batteries for a pack voltage of 144VDC.

Most people recommend Flooded Lead Acid as the best balance of initial cost, capacity, and cycle life (charge/discharge). However, I didn't want to get involved in the water maintenance and ventilation issues. I guess the biggest thing was that I didn't want buckets of acid in the trunk, just behind my kids' seats.

Absorbed Glass Mat (or Valve Regulated Lead Acid) are maintenance free, sealed, more or less dry, don't give off hydrogen during charging, and don't have to be mounted upright. They also have good characteristics around current draw, so acceleration is reportedly pretty snappy with AGMs. The downside is that charging a series pack of AGMs requires a more intelligent charger ($) to avoid damaging the batteries, and they tend to wear out more rapidly than FLAs if you draw them down too much too often. These are guaranteed for 400 cycles if typically drawn down to 80%Depth-of-Discharge and 800 cycles if only drawn to 40%DoD.

If you figure that a charge/drive cycle is going to happen 4 times a week, that's about two years if I drive it until it gets slow each time. However, I don't expect to drive it until it creeps each time, so hopefully this set will last for three or four years. By the time they're done, the price for LithiumIon batteries should be more palatable.

For more info on battery type selection considerations, look here . Or here. Or here.

Yabba Dabba Do

As if ripping the engine out of a functioning vehicle and selling off pieces wasn't committment enough, now I've really gone past the point of no return. Up until now, it still would've been plausible to salvage a V6 from some other bimmer, and pretend like the whole goal of the project had been to upgrade from the stock 4cyl to a hot-rod V6.

Not anymore. Now we're into ripping sheetmetal! At this point, we're ready to head off to the drive-in for a rack of dinosaur ribs Flintstone style!

We cut the floor out of the trunk so we can lower the rear batteries. This is the beginning of planning the structure of the battery box. We'll start on the front layout and battery box(es) once we have the motor installed.

Ungunking the seats

With the car out of the garage, I was able to spread out the seats and other upholstry pieces for some steam cleaning. Check out the color of the water that came back out through the vacuum.

Off to the Car-Spa for some rehab

I've got to be one of very few people in the world that is actually excited to see his car get hauled away on a flatbed. One night in early March, we hauled the prime-mover-less 318ti down to a buddy's machine/fab shop for the mechanical work.

They're going to design & build the motor/transmssion adapter plate and coupling, motor mounts, and battery boxes.

It felt pretty silly moving it out of the garage into the driveway. I had to crouch inside the car and steer while James pushed. With electric windows stuck up (no battery, no wiring harness, therefore no rolling up or down), and a narrow garage door to navigate, we couldn't have the door open to walk & steer. Additionally, all the seats are out, so there's nothing to sit on. The good news was that with no engine, trans and a whole bunch of other stuff, the car moves pretty easily with just a nudge.