DIY Electric Car Forums banner

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

57260 Views 636 Replies 23 Participants Last post by  remy_martian
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.
581 - 600 of 637 Posts

· Registered
1986 Honda CRX (EM57 2013 Leaf Motor)
Joined
·
439 Posts
Discussion Starter · #581 ·
You may not know this, but PVC gives off chlorine gas when it burns, and urethane gives off cyanide, iirc ("smoke inhalation" is how fire deaths are described when it more likely is gas poisoning)....not a great choice in a passenger compartment to cover something that does catch fire on occasion. You need time to stop the car and get out. I went on a rant a few months ago on a guy who was trying to sell plastic battery boxes here (because they're "easy to fab") for use inside VW Beetles.

A battery box should be enclosed in metal....yours has no top to it so far....
Makes sense. I'll need to pick up more sheet metal then.
 

· Registered
Joined
·
21 Posts
The cover looks great! Well done. I would just skin the inside of it with 22ga steel. That wouldn't contain a battery fire (would anything?) but I think it would slow it down enough for you to get out of the car safely. A battery fire is also extremely rare, especially when good cells are used and a BMS is correctly installed. A few weeks ago, an e-bike caught on fire because someone used unbalanced RC-car batteries and no BMS. Just don't do anything stupid like that and you'll be fine.

Some metal would also make it a bit stronger for when you inevitably throw some groceries or something on top of it.

Great project overall! I've been reading through the thread over the past week but it's a long one. I bought my donor Leaf a few days ago and will be looking to this build for inspiration. Everything in your thread is extremely well documented, photographed, and detailed so it will really come in handy and I thank you for that!
 

· Registered
Joined
·
5,397 Posts
Pulling excess current, a weak cell, faulty wiring (Damien's Fire), a charger fault, an arc flash, or a cell puncture are among many reasons a NMC cell or pack can light off. A battery box needs to be metal, it needs to be SEALED off, and it needs to be able to vent pressure and hot gases (aka flames if combustion occurs) from lit cell(s) away from occupants. It needs to protect occupants and first responders from high voltage. It needs to survive a survivable crash, ideally.

Your "just put a plate behind the plastic" does none of that for a battery box IN THE PASSENGER COMPARTMENT. It would be found to be negligent in any courtroom, in my opinion, to do what you propose if a cell or more lights off or someone gets electrocuted because a cover is removable.

It would kill our hobby if people were injured or died as a result of a shit build...the fossil fuel zealots pick up EVERY EV fire and cover it widely in the press, despite dozens of ICE fires daily. An electrocution would be a press field day.

The box needs a lid to seal it off from passengers. It also should have a pressure relief blowout down below.

It's never a problem until there's a problem.
 

· Registered
1986 Honda CRX (EM57 2013 Leaf Motor)
Joined
·
439 Posts
Discussion Starter · #584 ·
Weak cell is how my last battery pack got fried. Ironically the first warning signs was a scent that was rather "sweet". That cell was below voltage and was the reason I couldn't charge my pack.

And to make it worse, I tried to drive it home to which the weak cell "zero'd" and shorted the whole pack, stranding me on the shoulder off the fast lane on the freeway. And then it started smoking as I considered whether it was safer to exit the car on the shoulder of a freeway or to wait in the car and hope it doesn't burst into flames.

End result luckily was it only smoked and sizzled, no flames, and a crazy accordion battery when I actually disassembled it later.

So fully sealing the battery is certainly going to be a to-do item on the list. For now given this was all hacked together DIY I expect that I'll continue to monitor and configure the battery and its easier while its still accessible.

On the to-do list are:
-Brake conversion from vacuum booster to electric booster
-HVAC to use the AC pump from the leaf which wires directly to the battery
-Consider battery cooling/heating (on the maybe list since I don't expect extreme weathers)
-Fully seal the battery (since I shouldn't need to access the battery after HVAC is done)
-Decode and possibly output range data from canbus into current insight cluster
 

· Registered
1986 Honda CRX (EM57 2013 Leaf Motor)
Joined
·
439 Posts
Discussion Starter · #585 · (Edited)
Debating between converting to electric brake booster or axle teardown for machining.

Both require cutting, grinding.

Axles require a bit of cleaning and work to disassemble the axles. I need to recheck all my measurements and be prepared to send them out. I don't technically need to lift the car for this since I already have spare axles on the side.

Electric brake booster requires me to compare the position and size and shape of the electric brake ibooster vs my current vacuum based booster. I probably will need to make a new mounting adapter plate, connect adapters to the brake lines. Most critical is how the brake pedal and booster will "connect" and so there will need to be some comparison and work there. Finally once thats all hooked up, I'll need to bleed all the brake lines.

I guess I'll go with whatever my mood feels like this weekend.

From a misc side, I added some security kill switches to the car to make car theft more difficult (necessary in my city) and upgraded my LED cargo lights.

Its the little small victories.
Automotive parking light Motor vehicle Hood Vehicle Trunk


Tore out the janky LEDs I wired in back when I was a broke college student
Wood Shipping box Electrician Safety glove Workwear


I mean look at this. LEDs were a box of 99 for like 5 dollars from Ebay so it was "cheap" for a poor college student
Safety glove Wood Tire Shipping box Wheel


The new LEDs are so clean. Its so much nicer when doing things properly.

Automotive tire Bicycle tire Hood Asphalt Wood


For bonus I also was modifying my daughter's powerwheels lol. Getting them started on EVs early :ROFLMAO:

Purple Pink Magenta Building sets Machine
 

· Registered
1986 Honda CRX (EM57 2013 Leaf Motor)
Joined
·
439 Posts
Discussion Starter · #586 ·
Spent a few hours trying to figure out why I couldn't get my CAN BUS interface to actually get any CAN Messages.

I'm thinking it might be a pinout issue....

So I'm using a New Eagle Leaf Light V2 Canbus interface and its supposedly similar to a Kvaser Leaf Light V2.

If so the Kvaser Leaf Light V2 DB9 pinout is as follows:
Font Parallel Rectangle Number Document


DB9 doesn't plug straight into the OBD2 connector and unfortunately for me, the DB9 to OBD2 adapter pinout is as follows:

Font Rectangle Circle Number Document

The OBD2 parts are right but the DB9 pins are not. So... either I buy a cable.. which is a crazy 70 dollars... or I rig an adapter that "corrects" my DB9 pins. I'll have to continuity check tomorrow morning to verify the pins are per the sales description. I guess this is what I get for spending 10 dollars on an adapter.
 

· Registered
Joined
·
5,397 Posts
Axles will mess you up if they fail and could total the
sheetmetal if they fail. They'll leave you stranded, exposed - all you need is wrong place, wrong time - if they merely snap/slip.

The brakes now work. They make vacuum pump noise. You're not the snowflake type (that I can tell, given your work ethic after the kids are in bed) where this is urgent.

I think your answer is easy. But it's not as interesting to do...
 

· Registered
1986 Honda CRX (EM57 2013 Leaf Motor)
Joined
·
439 Posts
Discussion Starter · #588 ·
Yea
Axles will mess you up if they fail and could total the
sheetmetal if they fail. They'll leave you stranded, exposed - all you need is wrong place, wrong time - if they merely snap/slip.

The brakes now work. They make vacuum pump noise. You're not the snowflake type (that I can tell, given your work ethic after the kids are in bed) where this is urgent.

I think your answer is easy. But it's not as interesting to do...
Yea I was going to go with axles since it's more a necessity. Sometimes I alternate what I'm working on to keep the momentum going and change things up. Like CANBUS.

I've driven the car about 2 times at this point since 12/31. I really don't leave the house much lol.

But since I went into the office for work (because they made me for a meeting), I did a range test :)

Now this part confuses me. Supposedly I calculated I was getting 2.18 miles for each SOC%. (5.9 miles/2.7% SOC delta). That equates to 218 miles of range on a 40kwh battery that usually gets about 150 miles in a Leaf that is 1000 lbs heavier. I understand the weight difference should help but that sounds too good to be true?

Which brings me to my next point I'm trying to research. I'm trying to figure out how the Nissan Leaf BMS calculates it's SOC (state of charge). My battery SOH, state of health, is not accurate due to swapped modules ans a new BMS from dealer parts. So it's certainly not calibrated.

If SOC is based on voltage, then my range is reasonably accurate. But I recall reading Nissan Leaf BMS calculates SOC based on GIDS. GIDS is based on SOH which is inaccurate thus meaning my real range isn't accurate either. Probably doesn't matter too much if I'm going to monitor my voltages but I really do wonder what the SOH and battery range is.

Now I just need to leave the house more often so I can get better range analysis. 5.9 miles isn't enough data.
 

· Registered
1986 Honda CRX (EM57 2013 Leaf Motor)
Joined
·
439 Posts
Discussion Starter · #590 ·

· Registered
Joined
·
1,970 Posts
What is the total weight of the car when on the road? a first-order guess at consumption for diy ev is to take 10% of the weight (0.1 x W) as the Whr/mile. Take the inverse to get miles per Wh, which can be converted to miles per kWh.

e.g if the car weighed 2,000 lbs, then a good diy build might use 200 Wh per mile, (0.2 kWh/mile). Take the inverse and get 5 miles per kWh.

If the battery pack was a 40 kWh pack, then max range expectation would be 40 x 5 = 200 miles.

This comes from Jack Rickard's days of building EV conversions. (evtv.me)
 

· Registered
1986 Honda CRX (EM57 2013 Leaf Motor)
Joined
·
439 Posts
Discussion Starter · #593 · (Edited)
What is the total weight of the car when on the road? a first-order guess at consumption for diy ev is to take 10% of the weight (0.1 x W) as the Whr/mile. Take the inverse to get miles per Wh, which can be converted to miles per kWh.

e.g if the car weighed 2,000 lbs, then a good diy build might use 200 Wh per mile, (0.2 kWh/mile). Take the inverse and get 5 miles per kWh.

If the battery pack was a 40 kWh pack, then max range expectation would be 40 x 5 = 200 miles.

This comes from Jack Rickard's days of building EV conversions. (evtv.me)
Curb weight without driver, 2494lbs.
Rectangle Gas Gadget Font Communication Device


Leaf curb weight is 3500lbs

Leaf gets about 3.7-4.1 miles per kwh according to reddits averages. I'll just go with 3.7 miles per kwh which puts a 3500 lb Leaf at 148 miles range which matches the range advertised. I suppose that means the Leaf gets about 1000/3.7 = 270.270 wh/mile or .27 kwh/mile. If I go with the weight then Leaf would otherwise be .35kwh per mile but it appears to be more efficient than that.

CRX is 2500lbs, so your numbers would 2500*0.1 = 250 wh per mile or .25 kwh/mile means I should get about 160 miles range.

But the Leaf is .27kwh/mile and not .35 kwh/mile. So that means its about .27kwh/mile / 3500 lbs = .000077143

.000077143 * 2500 = .1929 kwh per mile
40kwh / .1929 kwh per mile = 207.36 miles of range

wow. that means 200 isn't impossible.

If I take the 4.1 miles per kwh as the basis since 3.7 was an average...
1000wh/4.1miles/kwh = 243.902 wh/mile or .243902 kwh/mile

.243902 kwh/mile / 3500lbs = .00006968628571428571 kwh/mile per lb
.00006968628571428571 * 2500lbs = 0.1742157142857143 kwh/mile
40kwh / .17426 kwh/mile = 229.54 miles of range

Theoretical and optimistic numbers.
 

· Registered
Joined
·
710 Posts
It all comes down to how you drive and speed limits and weather etc etc. I would sometimes get 2.5mi/kwh on a bad day in my Leaf and on a good day get over 6mi/kwh. A guy set the record in a gen 1 Leaf 24kwh over 220 miles by driving 8 hours through the night in a subdivision that was under construction with cruise control set at 24mph.
 

· Registered
Joined
·
1,970 Posts
diy builds generally never get as good mileage as the OEMs, but there's always the possibility for an exception, and your car has an unusual weight advantage.

Jack's 10% rule of thumb is for diy builds, not OEMs. Back when i was driving a laef my average was 4.8 to 5 miles/kWh with eco driving, lots of coasting, very little braking, mostly 40-45 mph roads, tires at max pressure, etc
 

· Registered
1986 Honda CRX (EM57 2013 Leaf Motor)
Joined
·
439 Posts
Discussion Starter · #596 ·
I was driving through stop and go traffic yesterday at pretty low speeds. A lot of coasting. Couldn't do any regen braking since I was over 80% still. So probably better than usual.
 

· Registered
1986 Honda CRX (EM57 2013 Leaf Motor)
Joined
·
439 Posts
Discussion Starter · #597 ·
It all comes down to how you drive and speed limits and weather etc etc. I would sometimes get 2.5mi/kwh on a bad day in my Leaf and on a good day get over 6mi/kwh. A guy set the record in a gen 1 Leaf 24kwh over 220 miles by driving 8 hours through the night in a subdivision that was under construction with cruise control set at 24mph.
How do you measure the kWh consumed? Does Leaf spy keep a log?
 

· Registered
Joined
·
710 Posts
diy builds generally never get as good mileage as the OEMs, but there's always the possibility for an exception, and your car has an unusual weight advantage.

Jack's 10% rule of thumb is for diy builds, not OEMs. Back when i was driving a laef my average was 4.8 to 5 miles/kWh with eco driving, lots of coasting, very little braking, mostly 40-45 mph roads, tires at max pressure, etc
Usually a DIY build has a motor mated to a manual transmission or other such shenanigans. Windraver has basically supplanted a complete Leaf drivetrain into his car with very minimal modifications. It's narrower and shorter and a lot lighter. Of all the DIY EVs this one should be very efficient.

How do you measure the kWh consumed? Does Leaf spy keep a log?
I believe so. Otherwise you just have to make note of starting and stopping capacity.
 

· Registered
Joined
·
5,397 Posts
Your range issue is the kWh you actually have in the pack and your aero...drag coefficient and frontal area. Weight is a huge differentiator, but at highway speeds it's only about half the equation.

Having low rolling resistance tires is something your tires are working against you unless you redid yours with the ones off the Leaf.

In my experience with the Bolt EV, thrashing it doesn't make a lot of difference if regen is on. Temperature and tire pressure & type of tire are much bigger factors.
 
581 - 600 of 637 Posts
Top