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2002 BMW 325i Electric
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Discussion Starter · #1 ·
Wanted to post some progress of my electric conversion! The car has finally gotten to a driving stage after two years of work.

The original car was a 2002 BMW 325xi, with 202.000 miles
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Needed some suspension work, bushings and wheel bearings
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144kw DC motor
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Pulling engine and trans
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Electric motor in place
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Driving video!

It’s been a beast of a project. But I got a sponsor for the motor and controller, I got them together for $1100 and it’s capable of 144v @ 1000amps. So around 190hp, essentially the same as the I6 I pulled out of the car.
I also had to remove the all wheel drive components and swap to 325i parts, as the front AWD system was integrated into the oil pan (note the drive shaft coming from the trans to the side of the engine in the photos).
The car was $600, the motor/controller was $1,100, and the batteries were free. They’re just lead acid for now, to verify the system works, and I am working to source lithium based power for it as we speak. I am probably under $3500 for the entire project, and I am super happy with where it’s at right now.
If you want to follow updates, my site is electricbimmer.com, I am finally home from college to work on it again and hope to make some good progress.
 

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Looking good! I am curious about your adapter plate from the electric motor to the transmission - I didnt see that discussed when I skimmed your website. Did you keep the clutch and flywheel? Did your motor come with an adapter, or did you have something fabricated?
 

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Great stuff, we almost never see people come back to a community and post when they finish. We usually see them at the start when there's lots of questions, but then the sharing stops. Thanks for posting!
 

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2002 BMW 325i Electric
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Discussion Starter · #5 ·
Did you keep the clutch and flywheel? Did your motor come with an adapter, or did you have something fabricated?
I didn't keep the clutch and flywheel, I made an adaptor between the motor shaft and the transmission. Direct drive through the stock 5 speed.
Looking good! I am curious about your adapter plate from the electric motor to the transmission - I didnt see that discussed when I skimmed your website.
The motor adaptor plate is a funny story.
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My father is a mechanic of 40 years, so his tip to me was to use a pizza box. Hold it up against the transmission bell housing, stick 2 bolts through to hold it steady, and tap around the perimeter with a hammer. You get a perfect imprint, and we used that on a drill press to get the bolt holes perfect, and then traced it with a plasma torch to get the shape close enough. I plan to CNC cut a new steel adapter plate though, or maybe just polish up this existing one, I want a more professional finish since this is getting out of a 'prototype phase'.
 

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2002 BMW 325i Electric
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Discussion Starter · #6 ·
Great stuff, we almost never see people come back to a community and post when they finish. We usually see them at the start when there's lots of questions, but then the sharing stops. Thanks for posting!
This is just getting started, I am excited for the future. I might have secured a sponsor for a fresh fully adjustable suspension, and I have a deal lined up for a proper battery pack. Ditching the bulky inefficient lead acid that I was just using for testing, for hopefully around 5-10kW of lithium.
 

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I didn't keep the clutch and flywheel, I made an adaptor between the motor shaft and the transmission. Direct drive through the stock 5 speed.
Do you have a picture of the adapter you made? I am curious, because the motor to transmission connection is still a bit of an uncertain area for me. I have read some stories of what can go wrong if the alignment is not accurate (I think the spec for runout on my flywheel is something like .004"). My plan is to take the electric motor, transmission and engine block in to a local tuning shop that has done engine swaps before, and get them to make me the parts. I am not sure how much that is going to cost, but I do not have the machine tools to do the job myself.
 

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2002 BMW 325i Electric
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Discussion Starter · #8 ·
Do you have a picture of the adapter you made? I am curious, because the motor to transmission connection is still a bit of an uncertain area for me. I have read some stories of what can go wrong if the alignment is not accurate (I think the spec for runout on my flywheel is something like .004"). My plan is to take the electric motor, transmission and engine block in to a local tuning shop that has done engine swaps before, and get them to make me the parts. I am not sure how much that is going to cost, but I do not have the machine tools to do the job myself.
I looked everywhere for the photo I took, I know I had one of it in the vice after I finish welded it together, but I can’t find it for the life of me.

My process was to repurpose part of the old clutch disk. The center splined area for the clutch was held in by press fit. I used a hydraulic press to pop it out, and placed my motor adaptor coupler and the clutch coupler together in a lathe. Then I welded it all the way around, the lathe made sure they stayed in perfect alignment. The motor sounds happy and smooth as it drives, no vibrations or grinding of the input shaft bearing.
 

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It sounds like you have a well appointed shop, and I bet that coupler will work out well. I am going to try and find a forklift motor with the matching splined brake drum, and then have a machinist mate that to the lopped off end of the driveshaft out of the old engine. I look forward to seeing your progress. What kind of batteries are you thinking of using for your lithium upgrade?
 

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Discussion Starter · #10 ·
What kind of batteries are you thinking of using for your lithium upgrade?
I am contemplating using something like Nissan Leaf/toyota cells and assembling a module, but then there's also options like the LG chem batteries that seem like a great deal if I can figure out how to charge/interface with them. Not looking to break the bank, but I am aware it's going to become the most expensive part of this build. The mechanical things are the cheap aspects.
 
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