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1986 CRX EV conversion (Nissan Leaf Donor) - Now Running and Misc upgrades

75560 Views 691 Replies 24 Participants Last post by  windraver
I'm new and am planning to convert my 1986 Honda CRX into an EV. I have a 2015 Fiat 500e for parts but from what I know so far, the Fiat is sensitive and difficult to use for parts. I believe it uses the Bosch 180/120 based on my Google fu. I've sourced the wiring diagram for the vehicle and confirmed it is indeed a 3 phase AC motor, one for each phase, 2 wires to sense temperature, and another 6 for the resolve (excitor, sin, cos). The biggest challenge is that Fiat uses canbus and the controller, inverter, battery, and more likely will not operate without all the parts. The car almost disabled itself when I changed the radio to android auto makes a good example. I am studying how canbus works in order to see if I can either ignore errors or maybe even hack the system to work.

As back up if I have to build from scratch, I have a separate thread pending approval where I'm asking about the compatibility of the Bosch SMG 180/120 with the Scott drive 250 AC controller.

Also I'm reading I might need an inverter? And what else? I'm still digging through the site trying to figure out what are all the parts needed to run an EV with an AC motor, which seems to be more complex and less popular than running DC. So guides or hints are welcome as I learn the anatomy of an EV.
Edit (2021-12-06):
Current project is now to convert the 1986 Honda CRX using a 2013 Nissan Leaf as a donor car in combination with the Resolve-EV Controller.
Edit (2021-12-23):
Project has begun; Battery Dropped; still need a machine shop to make parts.
Edit (2022-07-14):
Car has been running since June 2022. Car has been inspected by the California Referee Station and certified as an EV. DMV has issued registration though they're still trying to figure out internally how to actually label my car as an EV.

My latest work on this build has been to upgrade the battery from 24kwh to 40kwh. Batteries are installed but I still am working out the BMS issues as a bruteforce upgrade doesn't accurately recognize the battery capacity differences.

The to-do list is on-going and always evolving so although the car is running, I'm likely to be doing some new upgrade or change all the time.
Edit (2022-10-23):
Started building a battery box which is the "final battery" box. Still in the planning state but measure many times and cut once.
Edit (2022-12-27):
Battery Box is built and now revising the bus bars and BMS connections to the latest design.
Edit 2023-01-10
Got it running on 2022-12-30. And got it back on the ground and took it on a road test 2022-12-31

Been cleaning up and doing misc upgrades since.
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So full assembly is definitely too tall.

Transmission is 13.5 inches. Adapter plate is 18mm so less than an inch. Enough room for motor and transmission but I will have to turn the motor around and have it run in the opposite direction so I'll need to think about how that'll fit and work.

CRX engine bay is very small so I really need to think about how everything will fit. Will take off the PDU shortly and maybe test fit the transmission.

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I do sort of wonder if a short PDU cover would work but I'm guess that is a build not buy so it'll probably take some more research to know for certain.
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Took off the PDU:
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Looking at the Honda transmission, the axles are slightly higher than what I had the Leaf full assembly at so its likely the PDU won't clear. I'm not even the axle will clear. I'll have to test it another time.
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Even with just the inverter, its reaching up pretty high:
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They're at the same height. Leaf is slightly back but it isn't bad.
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Looking at it, I'm not sure if the PDU would fit over the transmission to the side. I
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transmissions side by side comparison:
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Leaf spline to axle is about 7.5"
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Civic transmission spline to axle is 7"
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Time lapse for the day:
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I think the PDM will fit over on the other side above the transmission. Just barely.

Another benefit to using the LEAF gearbox is that the axles will be more equal length which will reduce torque steer. The Honda trans might exacerbate torque steer.
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There are two copper straps in the Leaf inverter, far from being "bars", that connect the PDM to the inverter. Those are easily removed from the capacitor:

(this is a good teardown of the inverter if you like seeing EV electronics porn)

There is no reason those four screws can't be used to direct attach a power cable. Two electrical, two strain relief and housing bushing attach.
Strap, bar... how flexible are these? They're not, but call them what you want.

Yes, it looks like the cables could come right into the top of the inverter, and terminate on the capacitor... but did Electric Land Cruiser do that? If anyone does, I suggest that they provide much better strain relief than just filling the hole in the housing with silicone sealant. Sure, a rational solution would include a (presumably 3D-printed) cable clamp which would bolt in like the part which was removed.

However, to keep assembly height down, that copper strap pair can be deleted and cables appear to be able to enter the side of a modified inverter case.
My guess is that most builders won't want to modify the inverter casing, especially since a good modification would include building up or welding in something around any opening which is cut.... but it could be a slick solution, almost restoring the original Leaf design which used external cables.
You have other options for DC-DC and charging besides the PDU. More money, but may help in tucking the boxes in wherever they fit.

I agree that it looks like the PDU might fit over the transmission.
Axle does not fit. :(

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I would need an intermediate shaft to make it work.

I put in the coupler to center the transmission and motor before testing the axle.
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This puts me at a decision path:
- Civic transmission
- Leaf transmission

Civic transmission pros:
  • reuse 2/3 mounts
  • use existing speedometer/gauge cluster
  • use existing 1/2 axles
  • use coupler
  • 5 speed options
  • reverse switch is on the transmission which works easily with existing crx wiring

Civic transmission cons:
  • need custom intermediate shaft and one custom axle (maybe from first gen integra?)
  • speed, torque, gear ratios, and other items raised earlier in the thread

Leaf transmission pro:
  • Smaller transmission
  • more space for PDU and other things
  • axles will clear motor

Leaf transmission Cons:
  • axles still need to be customized to fit the crx wheel hubs
  • need to fabricate 3 mounts
  • need speedo and gauge cluster solution

Need to think and explore options and determine what's really important.

Coincidentally, I received notice to smog my car by March for registration sooo... I need this car moving before then. Lol. At least the motor and car should be moving and I can maybe do revisions after I get it legalized by California.

decision, due to time constraints, I'll take the "ez" route which is Leaf transmission which is the "fastest" route to getting the car moving.

So to-do checklist:
  • Need to buy steel this week to make mounts
  • Need cardboard to make template for mounts
  • Either make temporary axles or get a machine shop to make them if they can finish in time.
  • need to schedule time with California ARB to get the car legalized
  • Need to wire the resolve EV
  • Need to disassemble battery and just mount it securely for now. Nicer mounting to come later?
  • get the car to drive?

One of the things I wanted to do was cut and weld a box going down where the fuel tank used to be for batteries because I feel like its wasted space and doing so would place the batteries at a lower gravity point. This would have to come "later" maybe depending on timing. First goal is to mount the motor connect it to axles.

Apologies for my brain dump. :)

Also when does a thread go from member introduction to a "build"? section? :D
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The mods can move it all into a build thread.

You might be able to sleeve the axles with pipe after you cut them and weld it. Won't be balanced, but you don't care in Phase I.

Batteries in the back seat and trunk in two makeshift boxes just to get rolling? Toss the two orange HV cables, running from the boxes to the inverter, over your shoulder while driving 😂

Charger is a don't care at this point, since you can charge with the PDM sitting on a bench in the garage. For what you need to do, you may not need to charge at all for Phase 1.
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Alright, update for the night/morning (4:40am)

First time lapse for the axle check and then pulling the motor out:

After that I pulled my 12v battery box out. It was originally relocated to the trunk. In case anyone was looking to relocate a 12v, BMWs in the junk yard make great resources since many of them have the battery in the trunk. Pull the cabling and they're great for any battery relocation work.
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Took out the spare. Turns out it was flat. This space will be taken for the battery.

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Took out the glove box and then pulled the fan, heater, ac cores. Note to self to add a cabin air filter before I put this back in (Mk1 crx doesn't have a cabin air filter)
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Unplugged the ECU and started detangling the engine harness out.
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And the harness is out.

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As for why I'm pulling apart the interior, it is required that I remove all fuel related parts from the car for California to legalize it:

Can I convert my car to be an electric vehicle?
Any vehicle registered in California may be converted to a 100% electric drive, as long as all power is supplied by on-board batteries. All combustion and fuel system components must be removed prior to inspection by a California Bureau of Automotive Repairs Referee station. The vehicle must arrive at the inspection site under its own power, and the referee will also visually inspect to ensure that the vehicle has adequate battery storage capacity for 100% electric operation. Once the inspection is complete, the referee will sign a DMV "statement of Facts" form so that the vehicle can be registered as an EV and removed from the periodic smog inspection program. The statement of fact form is returned to the California department of motor vehicles. To schedule an appointment with California Bureau of Automotive Repairs Referee station, please call (800) 622-7733.
Finally a time lapse of the interior disassembly.

I expect that tomorrow, I will finish pulling apart the interior (dash), pull the fuel lines, and begin making mocks for the mounts.

Monday is my last day off for the holidays (they gave us a week off) so my updates will slow down after Monday :(
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I tried to go buy some steel but they were closed. Good for them since its new years but bummer for me lol.

First I started with dropping back in the motor+inverter+leaf transmission for fitment planning. I don't have metal so I left it there hanging. I also took a look at the axles to see if there was any way they might be an "easy" conversion but I decided to put that aside as I needed to prioritize removing the fuel system first.

So to get to the fuel system, most of the interior had to be taken out starting with the dash:
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I really need to reorganize this wiring.... a bunch of it are left over wiring or mods I've done in the past that need to be cleaned up. Also the old wiring before my engine swap is mostly still around so that needs to be cleaned up. With an EV motor going in, wiring for things like the distributor might not be necessary.
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In order to get the fuel pipe out, I had to take off the side skirt. Which turned out to be more complicated since the car was lifted by its sides and the side skirts being held in place. Had to take out the seatbelt. After basically gutting the inside and outside and underside, I finally got this darn pipe out.
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It came out of here:
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The fuel lines were another monster to deal with. I had to take off the pedals. The lines are quite "fitted" as in they don't come out without slightly bending them. I wish the best of luck to the gentlemen who is taking these from me as it will be very painful to install.
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I picked up the OEM engine mounts. They aren't as stiff and they're cheap (20-30 bucks). I'll need to make brackets to enable them to reach the motor.

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The usual timelapse for the day.

I am wondering if I should prioritize mounts or wiring next. hmm... I might try some other sources for metal perhaps.
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Misc thought or maybe question before I end the night/morning. Should the motor be mounted towards the center, or towards a specific side? I was thinking of keeping it to a side to leave space the the PDU. Thoughts?
You'll get fed up pretty quickly with torque steer if you have unequal length, same-diameter, axle shafts. You'll have full torque from a standing start now. Tuning it out will be costly in time and axle iterations unless you can reuse the original unequal axle setup.
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You'll get fed up pretty quickly with torque steer if you have unequal length, same-diameter, axle shafts. You'll have full torque from a standing start now. Tuning it out will be costly in time and axle iterations unless you can reuse the original unequal axle setup.
So what you suggest then is to center it the transmission axle points as much as possible to reduce torque steer? And I didn't realize the reason I didn't experience as much torque steer was due to the diameter of the larger axle. This car has never had "power" before so I never really experienced noticable torque steer 🤣

The issue then lies with the PDU fitment if I center because... I really have no idea where it'd otherwise fit. The engine bay is tiny.
And I didn't realize the reason I didn't experience as much torque steer was due to the diameter of the larger axle. This car has never had "power" before so I never really experienced noticable torque steer 🤣
The larger (and hollow tube instead of solid bar) shaft is torsionally stiffer. That may be done just to keep the longer shaft from "whipping" (bending with rotation), but it can also match the torsional wind-up of the softer but shorter shaft; mismatched torsional wind-up is one source of torque steer... but not the only one.

In the 1980's I test-drove several compact front wheel drive cars, and the amount of torque steer varied greatly between them. By far the worst was the Dodge Colt (a rebadged Mitsubishi Mirage); it had decent power but not exceptional - the real problem was the axle and suspension design. My current Mazda 3 has far more power and a similarly offset powertrain with unequal halfshafts, but no torque steer problem.
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Z24 Cavalier at that time was a handful. Your car had a larger diameter on the longer axle originally.

If you have no choice in terms of space, offset it, then when you get grumpy about torque steer, throw money and time at tuning the axles.

If I was in your shoes, I'd go symmetrical and ditch the Nissan PDM (you can sell it to recover costs) for separate charger and DC-DC boxes that you can tuck in here and there.

I'd even put forward the radical idea that if the car is home-based, the HV charger doesn't even have to be in the car. Hit @gregski up for one of his patent-pending gravity-grounded dryer cord setups 😂
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Based on what you're all saying, the goal is to make the axles as similar in length as possible. Ironically, that might actually place the motor to one side. The axles meet the transmission at it's driver side so in order to center that point and have equal length axles, the motor actually has to sit as close as possible to the passenger side.

Pictures to demonstrate

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Cabling came in the mail. Based on what I searched here, 1/0 awg cables are good to run from inverter to PDU?

Also orange PVC water proof tape is annoyingly hard to find.

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So I went to Lowes this morning because I recalled they had some metal. I was disappointed because most of the metal was too thin. I found some thick metal bars that were angled and I bought those.

I was going to make a template, weld, then clean up but I couldn't even get the welder out.

So I cleaned up first.

As per the thread, I positioned the motor where it would mount in the center, which is 26 inches from either fender.
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using my civic transmission as reference as to where the axles should originate, I determined it was 8 inches horizontal from the mount:

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And then it was 5 inches down to the center of the axle:
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I tried to eyeball it with a tape measure but it wasn't going well until I recalled I had a laser leveler which I then used as guidance.

That worked really well:
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After a ton of cutting and welding, its terrible looking. I'm left wondering if I should build out a cross member instead for the two front mounts. which would allow me to use the original Leaf mounts in front that were also on the cross member.
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Also I ran out of Argon so I had to stop welding.

Since I have an early day tomorrow, I'll just rest early and tomorrow will pick up metal from the metal super market and more gas for welding. I should also pick up some pipes for welding the axles.

The go forward plan is to do as much motor mounting and axles and then move into wiring. And then somehow fit the battery that is bigger than the CRX. A part of me wants to really make use of the space freed by removing the fuel tank but that would mean cutting out the floor in the car, reinforcing the frame, welding a sealed box, etc. Its no small task.
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I'd pick up the mount off a crossmember. It can sneak under the compartment and free up volume you need in there, not to mention stiffen the front of the car up for handling reasons.
One more thing...I wouldn't be shy about putting the batteries in that front compartment to balance the car, considering you don't really care where the PDM (or equivalent) goes, so keep your options open there if you can.

Don't forget that you can tilt the drive around the axle ports (like the old Dodge Slant 6) to make or delete space, though it might come at a ground clearance price. An inch or two could make a difference in what you can get in there.
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