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

56554 Views 625 Replies 23 Participants Last post by  dddrewski
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.
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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.
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Edit (2021-12-23):
Project has begun; Battery Dropped; still need a machine shop to make parts.
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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.
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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.
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Edit (2022-12-27):
Battery Box is built and now revising the bus bars and BMS connections to the latest design.
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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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1986 Honda CRX (EM57 2013 Leaf Motor)
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Discussion Starter · #481 ·
Finally found time to go back out to the garage.

It's a bit of a mess so I started with cleaning up.

Turns out it's hard to clean when I have a few open projects so after making somewhat of a walkway, I took out the rear to prep for the battery box

Car Vehicle Hood Motor vehicle Trunk


I have quite a number of holes to seal because I really bolted this thing down...

Also disassembled one of the batteries so I can stack it for space. I probably should just get rid of these 40kwh modules.

Automotive tire Motor vehicle Wheel Asphalt Road surface


I probably will move the cables and then start measuring and planning my cuts. Might also mock the box first before cutting.

Motor vehicle Automotive tire Electrical wiring Trunk Gas
 

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Discussion Starter · #482 ·
Back out at it.

Pulled speakers and started to clean out the back more

Vehicle Car Hood Motor vehicle Automotive lighting


Pulled the interior

Motor vehicle Hood Automotive lighting Car Vehicle


Its not easy to move the battery around and I needed something to help me plan my dimensions correctly so I thought it'd be a good idea to use the framing from the batteries

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Here you can see that my challenge will be finding some part of the car's frame to bolt to. Might have to get creative about how I connect to the body of the car...

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Underneath you can see there isn't much to bolt to either. Maybe I could use the bolt holes where the fuel pump used to be.

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tis not symmetrical. The opposite side doesn't have the same bolt holes :(

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Time to try this under the car
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The short is it doesn't fit.
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The box will certainly be wider and it will impact the brake lines. I'd rather redo the layout of the battery than modify my brakelines.
Tire Wheel Automotive tire Hood Motor vehicle


Tire Automotive tire Tread Motor vehicle Wheel


to be continued...
 

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Discussion Starter · #483 ·
Continued...

Front and back has a lot of space so the issue really is only width.

Front side of battery frame
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Back side of the battery frame
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I need to ensure there is room to still do maintenance on other parts of the car like brakes and suspension so its better to reduce the width of the lower box.

Here you can see the frame pretty much is sitting on the brake lines. A box outside the frame wouldn't clear.
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Looking up, since theres a dip in the car, there is plenty of room to put the battery box a bit higher, or have a taller battery box.
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Perhaps the solution was right in front of me all along:
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I would flip that stack but effectively, the bottom stack would be 3 vertical stacks and the top stack would be the 12/24 module stack. The design would support the 40kwh battery pack.

Uncompressed, the triple vertical stacks are 11 in
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The back has a dip and currently it already clears the bottom of the car:
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The wider horizontal stack is about 9 inches wide. So about 2 inches shorter. Cutting the frame as I've planned would leave plenty of room to ensure the batteries clear the road.

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The triple vertical stacks are about 27 inches wide
Tire Automotive tire Wheel Vehicle Tread


Using the OEM battery box, I can see the box was about 36.5 inches wide.

Tire Automotive tire Wheel Vehicle Tread


to be continued...
 

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Discussion Starter · #484 ·
I need to draw straighter lines but here I can see what I plan to cut out. Also I marked where the rear sway bar beam is.

Hood Automotive exterior Gas Bumper Auto part


The cables give us an idea where the lines are underneath
Automotive tire Electrical wiring Gas Electrical supply Cable


And this is the beam that is responsible for the rear sway bar and suspension.
Tire Wheel Vehicle Automotive tire Hood


Part of me wonders if the beam can help with the structural integrity of the battery box and frame.. I'll need to think about how I'd bring it together...

Random thought about how I might support the upper battery horizontal stack above it. Either it'd be a flat sheet with reinforcement beams. Or maybe just beams so I have space to access and work on the batteries if needed.
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If I'm doing vertical stacks, I'll probably reuse these:
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Marked for cutting and welding.
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I'll have to spend the rest of the day cleaning before I can cut and weld though.
Tire Automotive tire Motor vehicle Wheel Automotive design
 

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Discussion Starter · #485 ·
Some planning

Idea is to have the bolting down of the bottom battery stack be underneath the car instead. Might need some gaskets.

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Page two of the plan

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The frame likely needs to be two pieces so that I can actually fit in the bottom box. If both pieces were welded together, it might be too tall to fit into the car.

The bottom piece would have to be designed so that it not only reinforces the frame of the car but can bolt down to the frame on its own. The top frame would be "add-on" to it. Bottom battery should peek out so that I can connect the conduits.

Speaking of conduits, I need to figure out how to run them. Also will have to reroute the charging cables. BMS wiring is going to be a pain again.
 

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Looks like the same headaches and similar location to what I'm going through. I ended up with 2x2x2 between the frame and 4x1x4 above. I skipped the sheet metal, used angle iron to mount the OEM battery brackets. Definitely some environmental issues, and will be better when (if) I redo it.

I'm not familiar with CRX, but maybe there are hardpoints on suspension to support the bottom box? I'm sandwiching between subframe and frame.
 

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Discussion Starter · #487 ·
Looks like the same headaches and similar location to what I'm going through. I ended up with 2x2x2 between the frame and 4x1x4 above. I skipped the sheet metal, used angle iron to mount the OEM battery brackets. Definitely some environmental issues, and will be better when (if) I redo it.

I'm not familiar with CRX, but maybe there are hardpoints on suspension to support the bottom box? I'm sandwiching between subframe and frame.
I definitely would've left it much longer if my battery didn't fry.

The entire CRX is a bunch of thin metal. I was thinking angled steel and maybe find a way to make some brackets that could reach some structural anchor points for more integrity. It'd be easier if I had rear seats since there would be bolt holes for the belts but alas this is a 2 seater. Effectively I'm probably reinforcing the frame of my car 🤣.

Perhaps my largest difficulty is my requirement that this box be entirely removable. I always assume things break so I need to be able to take it out and service the brakes and suspension of the original car.

Overall, the more I work on it, the more it seems feasible so it's really just more planning and prepping before I make my first cuts.

Good luck with your batteries!
 

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I'd cut the trunk floor out completely, leaving only the subframe of the car in place. Delete brake line runs and anything else in your way (they are not a constraint, route new ones later - in California, there's no such thing as replacing brake lines unless it's a beach buggy). Fab a 3mm battery tub that bolts to the subframe rails, dropping it as low as you need for ground clearance.

Build your stack in that tub. The tub lid then becomes your trunk floor and finish out new sheet metal to finish out the trunk floor you deleted.

Working with the existing floor is an unnecessary constraint in my book. Preserve the subframe and suspension mounts.
 

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Perhaps my largest difficulty is my requirement that this box be entirely removable. I always assume things break so I need to be able to take it out and service the brakes and suspension of the original car.

Overall, the more I work on it, the more it seems feasible so it's really just more planning and prepping before I make my first cuts.

Good luck with your batteries!
Yeah... My next version would be more "removable", with about same difficulty as original gas tank. Drop the subframe, clear the brake lines, drop the battery box. 1/2 day, but would drop straight down and out with a transmission jack.

And like Remy said, I'd clear out all the sheet metal. I cut the minimum and it's just in the way.
 

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Discussion Starter · #490 ·
Perhaps the challenge is the CRX is mostly thin sheet metal with a few folds. It's not a sturdy car so cutting to the "subframe" is pretty much cutting out the entire rear of the car. My plan is to use the subframe along with some of the existing sheet body. In a sense, the battery box frame should act as an additional subframe to reinforce the car if I do this right. Especially since I'm going to rearrange the battery, I might as well cut less than I have to.
 

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This is where I was going. You could build a, ahem, "structural battery" that ties the two subframes together as it forms an effective u channel, a deep and wide one with two faces in shear, between them. You do not cut into the subframe channels - you attach your box face to their inner faces.

The lowered CG is a bonus, almost as if some were under the floor, for body roll and you get most, if not all, of your trunk and rear seat back.
 

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Discussion Starter · #492 · (Edited)
more doodling...

Revised the battery stack layout since it'll make it easier to run the power.

Doodled on how I can build a bracket that connects to the frame and also establishes a front subframe since there isn't one.
Rectangle Handwriting Font Slope Parallel


The idea is I'll clamp the welds on the subframe or extend them so I can better secure and bolt down the battery box and frame. Given the lack of framing, this should greatly reinforce the car.

more ugly doodling here. yellow is likely a beam I'll connect to the subframe. Blue is a square tube that will go across the front to act as a front subframe. Green is a plate that will likely be used to clamp with the top for more integrity. I might also consider making a bracket that connects to this custom frame that will bolt into the bolt holes on the frame where the fuel pump used to bolt to.
Tire Wheel Vehicle Automotive tire Motor vehicle


Opposite side, same idea.

Automotive tire Hood Motor vehicle Tire Vehicle


The hardest part will be any welding I do to the frame. Last time I tried to patch a hole in the spare tire well, I simply burned through. The metal is extremely thin. Maybe I should practice on thin sheet metal before starting. Maybe start by plugging holes I made 😅


Edit:

Made the battery layout more readable:
Rectangle Font Parallel Pattern Number
 

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Discussion Starter · #494 ·
I would not weld to the subframe. I've seen your welding 😂

Mount the box to the trailing link pivot bolts as the main load transfer point and then bolt up to those holes just ahead of the spring pockets.
I was thinking bolting as well. I wouldn't try to weld to the subframe... Hence why I also would cut away and just make a tub. I wouldn't trust any weld I do to actually secure to the subframe for any tub I could build. And plus I need it to be removable. Lots of planning. The trailing link pivot bolts are an interesting idea though. I'll look into it.
 

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You'll need to put a small spacer bushing, or even better attach a plate to the recessed area so it's slightly proud (you can use the brake clip bolt hole to hold the plate in place), in on the inner side of the pivot bolts if you decide to use them. Don't pound those stiffener creases flat in that pivot bracket.
 

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Discussion Starter · #496 ·
Small/big update.

After months of not being able to find a donor car for another pack of 40kwh Leaf Battery modules, I went ahead and bought it from Aliexpress. Its cheaper than any donor (avg 11k+) and will actually ship to to me. Also they claim it to be 92-95% SOH.

Aliexpress claims to have a 75 day protection guarantee so hopefully its decent. Also next level I could always escalate to paypal. Or my credit card company if its not as described. Will definitely report back on the quality of these batteries.

Rectangle Font Wall Material property Wood


wish me luck 😅
 

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Discussion Starter · #497 ·
Starting a list of To do list so I can make progress.

Items may be out of order but it'll give me things to cross off

  • cut battery compression plate
  • weld battery compression plates (3 vertical stacks)
  • test fit batteries with compression plates
  • measure dimensions battery vertical stacks
  • plan with dimensions battery support structure
  • measure and cardboard template subframe for battery support
  • align both designs and verify how they'll mount
  • cut car rear to make space for the subframe being built
  • make subframe
  • install subframe
  • make lower battery box
  • make battery structure
  • install battery box and structure to subframe
  • redo battery connectors
  • redo battery BMS connections
  • add installation brackets to top compression plates
  • build vertical stack battery
  • drop in lower vertical battery
  • plan and design top battery structure
  • build top battery structure
  • install top battery structure
  • install/drop in top horizontal stack battery
  • run wiring
  • clean up charging wires
  • build a box for battery junction and for service connector
  • test drive
  • get axle splines cut by machine shop
  • figure out AC/heat/hvac
  • install 40kwh batteries
  • record civic canbus and replicate output to Thor for vehicle sounds and build a tool that consumes throttle position and converts it into out for Thor.
  • rebuild rear "trunk"

If I can somehow do the first 7 things this weekend, it'll be good.
 

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Discussion Starter · #498 ·
Just realized no matter which way I flip the 40kwh gen4 modules, they'll remain the same lol
Motor vehicle Bumper Gas Automotive exterior Machine


The diagram I made only works for 24 kWh so I'll need to replan how I'll run it.

Current plan for reference would only work for 24kwh modules:
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Thinking about... It'll probably work if I reverse it...
 

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Just realized no matter which way I flip the 40kwh gen4 modules, they'll remain the same lol
I thought that's what I saw in updated pack diagrams! There are not any more L vs R modules, they are all the same... I haven't sketched out my future upgrade, but definitely good to know for sure! Good luck!
 
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