The build began with a 2000 Porsche Boxster S. This is the 6-speed version. It has a low drag coefficient, is rather light, and looks great. Fortunately, there is a common issue with the 2000-era Porsches which destroys engines. Thus, the car was available for $3500 without the engine--usually removing the engine is a project in its own right. We washed the car a bit and got to work measuring, looking, and checking to figure out whether the motor of choice would fit and where the heck the batteries would go. Oh and how comfortable the vehicle was (very nice.)

Cosmetics should never be the top priority. So the first thing to do was buy the motor and inverter and start working on controlling, connecting, and mounting the combination. The motor is a Siemens 1PV5135-4WS14. AC induction, liquid cooling, and a very reasonable price tag. It appears to be capable of 220 lb-ft of torque or so at about 100kw. It ought to deliver very nice acceleration and good top speed. The inverter is a OEM product from Azure Dynamics, the DMOC645. 400Arms, 400V, and air cooling. However, it requires CAN control, which is done by a GEVCU: a glorified Arduino which translates the throttle pedal signal into CAN messages for the DMOC. It's expensive but looks very impressive with its IP67 enclosure and bundle of multicolored wires.

A slightly annoying thing about AC motors is that you can't just hook up a battery or two and see how she spins. The whole inverter setup has to be connected and powered, and the DMOC requires at least 120v. So I made a dangerous 240VAC to 330VDC rectifier with a 2200uF capacitor and bridge rectifier. Not dead yet...

Once the motor was spinning, we got to work on connecting it to the stock transmission. The shaft coupler was built by a local racing mechanic and looks absolutely amazing (and spins very smoothly). Both ends are splined parts from clutch plates; the transmission end is the original Porsche plate and the motor end is from a 1980 Nissan 200SX. The adapter plate was built by a machinist in Georgia who did quite a nice job. So once they were connected we had to figure out how to hold that 200lbs of motor in the compartment. A stock Porsche engine mount and a steel box (which I welded together) did the trick nicely. The whole assembly was then mounted in the car, connected to the inverter, and bolted together. It is very quiet except when regen is enabled.

Nissan Leaf batteries are an excellent value. For about $4000 you can get a 24kwh battery with BMS which is capable of 100kw+ output. The cells themselves were purchased from eBay, as was the Nissan BMS. The Nissan BMS costs about $70 and is purpose-built for Leaf cells. It requires lots of wiring and electronics work so as to have usable monitoring capability. The cells are mounted inside ABS boxes on either side of the motor. Unfortunately the handbrake cables were hitting the corners of the boxes, so we had to extend the cables and make sleeves for them out of copper pipe. This worked perfectly; the batteries fit very well and used the space very efficiently. Angle iron frames support the bottom of each box, and square tubes hold up all that weight.

DC fast charging is a desirable feature for an EV, especially one with such terrible range. CHAdeMO is the easiest standard to deal with, and since there is a station right here in St. Helena I got to work Googling similar projects. Click

Instrumentation! Probably a JLD404, Leaf Spy Pro on a cheap Android device, and a buzzer. The original speedo works fine. I blew up the tachometer unfortunately... It would have been an awesome ammeter. I'll probably stick a servo in there.

Power steering and power brakes are rather important, so we got an Opel PS pump. It is mounted in the rear trunk on some aluminum brackets, which helped to reduce the vibration transfer. The lines are connected to the original P/S line in the engine compartment through a metal shielded hose from Summit Racing. The pump draws significant current, apparently around 40A, so I wired it directly to the DC/DC converter (which sits above the motor in the engine compartment) using 8 gauge wire. It needs both 12V power and a signal from the ignition switch. When switched on, it slowly spools up over 5-10 seconds, producing a high pitched hum which sounds like a jet spooling up to speed. After reaching max RPM it settles down a bit and maintains the same speed even under load as long as there is sufficient 12V power. The Hella pump which we tried first was terribly loud even after being cast into foam and boxed. A Ford hybrid vacuum pump proved far quieter and also produces more vacuum more quickly. It's still sitting in the frunk and hasn't been bolted in.