ElectricSubaru


Last update: Jul 7 2017

Advice and Recommendations

I learned a lot by converting this car to electric. Some things worked out really well and others I would do differently. Here is my advice from the perspective of having completed the project.

Adapter

The motor adapter design I used has some drawbacks.

Here are some ideas for addressing these issues.

System Voltage

Use a minimum of 70 (3.2V) cells with a DC system. I used 50 cells which is not enough to compensate for voltage sag and back-EMF.

Keep the ECU and Harness Intact

I found that my car contained an immobilizer that was not happy without the ECU and caused a problem with the remote door locks.

In a car with fly-by-wire throttle, the cruise control is implemented in the ECU. It might be possible to keep the cruise control feature if you keep the throttle pedal connected to the ECU and use the existing electronic throttle body to control the motor controller throttle.

Keep the existing wiring harness intact as much as possible. This makes it easy to locate wires. You might want to connect to the existing wiring harness at a spot that seemed unlikely at the beginning of the project.

Transmission

Consider using an automatic transmission. My car sometimes gets into a harmonic surging and bucking mode that is alarming and tricky to get out of. Driving the car smoothly requires skillful knowledge and occasional left foot braking. The problem is due to slop and flex in the driveline working against the rotational inertia of the motor and flywheel. This issue prevents me from allowing anyone else to drive the car without an awkward explanation. I suspect the surest solution is the fluid coupling of an automatic transmission.

The TCU communicates with the ECU. Therefore, the ECU must stay and be provided enough signals to keep the TCU happy so that it does not go into fail safe mode.

If using an automatic transmission, the motor needs to idle. In that case, I would consider using the original alternator, power steering pump and air conditioning compressor. Reusing these accessories requires fabricating a mounting system and imposes a small tax on the available power and range. But the wiring is significantly simplified and there would be no need for a DC-DC converter. There would be a signification cost saving for power steering and air conditioning. Electric A/C is expensive and complex.

Charger

Locate the charger outside. Chargers get very hot. Possible locations are under the rear seats and under the hood.

Use the biggest charger you can manage. You can compensate for limited range by charging away from home. A large charger makes that option much more viable. For example, I would use the PFC5000 rather than the PFC2500.

Manuals and Parts

Get service manuals at wrxinfo.com and other documents at techinfo.subaru.com. Find Subaru part numbers at parts.subaru.com

Dealers with low part prices: generalmotorsparts.com parts.com quirkparts.com subaruonlineparts.com

Subaru Impreza Weight

Impreza models prior to 2002 are significantly lighter than later models.

Impreza Weight

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