Leaf transplant / organ donor feasibility?

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miscrms

Well-known member
Joined
Sep 5, 2014
Messages
142
Location
Phoenix, AZ
Hello all!

I'm hoping you might be so kind as to help me get up to speed on the Leaf systems, as I delve into this new project!

I've been very active in the Prius community for many years now, but my dream has always been to drive an EV. I've come pretty close to jumping into a conversion several times, but just never could make the design work out the way I wanted on a "reasonable" budget. It finally feels like the technology maturity and my personal finances are aligning to where this could really happen!

I've already purchased the intended subject of the project, a 1973 Saab Sonett. I've had a long fascination with them, in no small part due to their light weight and miniscule CdA. This one was already converted to a 96V DC electric drive system in the early 90's which is still operable today, making it a nice rolling chassis with the added benefit of some early EV grins :)
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I'm pretty impressed with what I've seen of the drive system that Nissan has come up with for the Leaf, and am seriously intrigued with idea of finding a wrecked Leaf and freeing its drive train from its "fleshy bonds." My assumption is this is no easy task, as I assume that like the Prius that I'm much more familiar with, the Leaf likely has a whole lot interaction going on between controllers and a million and one ways of freaking out if it thinks anything is amiss. My going in position would be to bring over as much of the Leaf's internals as necessary to lull the system into believing that its still safe and sound inside a Leaf, and then maybe see what can be gotten rid of or spoofed into compliance.

So that brings me (finally) to my questions:

1) Does anyone have a good sense of just how many systems would have to be brought over to keep the drive system happy, or at least keep it out of any significant degraded performance / error modes? I would be planning to use the whole drive system intact, motor, inverter, charger, bms, battery, controllers, probably cooling, etc. So what else likely has to be there to keep things copacetic? ABS, traction control, brakes and wheel sensors? Steering?

2) In terms of dealing with whatever issues the donor ex-Leaf may have and issues that come up during the project, what sort of diagnostic options are available? Is Leaf Spy powerful enough that I might get by with it? For the Prius I was able to pick up a generic "mini-VCI" interface for about $30 that gives me full access to the dealership diagnostic software, which has been invaluable. I'm guessing I won't be so lucky on the Leaf, as it looks like even the generic version of the Consult 3+ is around $1500? Has anyone actually tried one of those? Its not out of the question, but that's a lot of money to drop if it ends up not working very well ;)

Thanks very much for any insights you can provide to get me on the right track!

Rob
 
I think hood clearance will be a problem with the "whole stack" aka Charger, Power Distribution, Inverter, Motor/Tranaxle. Might work in the rear? You wouldnt need the ABS or much anything else. Getting all the CAN commands would be the problem. I know of only one guy who can talk to the inverter direct and he does not want to share the commands.

For your style of car Id go with an HPEVS AC-35 X2. If you just wanted to play with a leafs driveline/batt I'd get a vanagon to put it in.
 
Thanks for your thoughts, keep 'em coming :)

Yeah, clearance could be tight. Anyone have a height for the whole stack?

I was thinking the '11-12 setup might be more suitable, as it seems like you'd have a bit more flexibility moving the charger and inverter around. I'm not too worried about battery degradation (despite being in Phoenix) as I'm primarily building the car as a commuter which is only ~15-20 miles a day. I'm probably only putting ~5k a year on the Prius.

I'm more concerned about the width, the front track is only ~48" and the engine bay is about 29" wide. Eyeballing it, it seemed like using two of the short side drive shafts with the reduction gear output centered might almost work, but the AC compressor mount might interfere. Need to start getting some decent dimensions of all these things and start modeling.

Am I correct in thinking that if I am using the controllers out of the Leaf, I don't need to know how to talk directly to the inverter etc? I'm assuming the trick then becomes just how much other stuff you have to bring along to keep the controllers happy, which is why I was wondering about ABS and TC. As I recall the Prius tends to go into freak out mode without wheel speed data, but maybe the Leaf is more forgiving. I was surprised those youtube guys with the pegboard leaf seemed to have the motor spinning without wheel speed, but it was hard to tell exactly what was going on there.

Dual AC-35s would be awesome, but just the motor and controllers alone would cost more than a salvage Leaf ;)

I know its probably not the easiest development platform I've selected, but once you pop the fiberglass body off its pretty flexible ;)
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Thanks, I had seen that! Pretty awesome. Maybe I'm crazy, but my reaction to the video was "really? that's all?" ;) I guess engineers are just a little weird like that :)

Like I said above, I was surprised they could apparently get the motor to turn without feedback from the wheel speed sensors / ABS / TC system. Can the Leaf generally be run without traction control?

On the Prius the TC is pretty overbearing, supposedly to protect the electric motors from over rev. As I recall, to even get it to run on a dyno you have to both go into a special "diagnostic mode" to turn of TC, and disconnect the rear wheel speed sensors. Perhaps its more prone to overspeed by nature of the PSD variable gearing.

If the Leaf is happy to output full power without the ABS/TC system I'd say that bodes really well. Adapting the drive shafts to the existing hubs is one thing, but adapting over the brakes / knuckles / etc seems a bit more daunting.

Rob
 
Thanks for the links, I was thinking about getting in touch with him. He and his friend are also the ones who did the pegboard demo aren't they?

Rob
 
Well, after spending some quality time with the factory service manual I'm starting to think this might be pretty doable :)

I should probably start a new thread to discuss in more detail once I get into it a little farther, but here's what I've been looking at so far. Starting on page EVC-79 (MY 2011, June 2014 Rev), there is a handy table of failsafe conditions for the VCM by DTC code. I've started with the P31* CAN Communication Error Codes, thinking that this would likely give the first indicator of how the VCM would react if unable to communicate with a given controller on the CAN bus(es). Then I also looked at the failsafe tables for the inverter (TMS), charger (VC) and battery controller (LBC/EVB) for their responses to these same DTCs. The results are summarized in the table below:
17090845252_31c9d1b439_b.jpg


I still have a lot of other codes to wade through, but I have to say this looks encouraging to me. It almost looks as though one could get the VCM and EV-CAN components to operate more or less normally in the absence of any of the CAR-CAN controllers simply by providing the VCM with a ready signal on the appropriate pin. There may be still be a gotcha there somewhere, but that would be phenomenal.

EDIT: One caveat to above, without the Intelligent Brake Unit to generate regen torque requests I don't believe the VCM will attempt to employ any regenerative braking other than perhaps during coasting.

Rob
 
I've also started some rough CAD work to see how the components would fit. Its tricky to find accurate measurements of the Leaf parts, but this seems to be a decent estimate of how the motor/reducer, inverter, battery, and radiator would look in the frame. A bit cramped, but seems plausible ;)

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Rob
 
Well, as expected there is a complication related to omitting the BCM. There are several P16** errors described in the SEC section that relate to communications between the VCM and BCM which can result in the VCM refusing to go ready on request. P1610 for example looks to put the VCM in "lock mode" after going ready 5 consecutive times in the presence of BCM communication failures.

There may be a workaround, but there likely are some hurdles to clear if attempting to use the VCM without the BCM present. Using the BCM may also be possible, and even desirable, but it certainly adds many more complications as well.

Rob
 
Here is someone on Ecomodder working to put a LEAF drivetrain into an Insight:

http://ecomodder.com/forum/showthread.php/project-nissan-leaf-drivetrain-into-02-honda-insight-30966.html" onclick="window.open(this.href);return false;
 
Was just on ecomodder after a long absence and found this link in the insight thread. Very interesting, I am also very interested in your results because as I've thought about for my leafs retirement putting it in the mini which is also about 48" wide. I think I'd use the rear though, probably stick with the stock mini front subframe as others have put them in the rear for dual engine awd.
 
The EV TV guys have been spending their time lately on reverse engineering the (CAN) interfaces to OEM EV components so that they can be used in conversions. The LEAF drivetrain is one of their targets. You might want to checkout their efforts and/or contact them. http://evtv.me/
 
BTW, I've done quite a bit more work with the service manual and looking at DTC/failsafe dependencies for the various controllers. I'm currently tracking that effort in this thread on diyelectriccar:
http://www.diyelectriccar.com/forums/showthread.php/re-using-complete-leaf-drive-system-151458.html" onclick="window.open(this.href);return false;

Basically it all looks pretty feasible. It does seem like retaining the BCM is desirable in terms of avoiding problems with the security / immobilizer DTCs. That does mean you need to have a key, BCM, VCM, and security dongle all from the same car unless you have access to Consult for re-registering. LBC also has to be from same car.

I think the biggest unknown right now is the brakes. It seems like you can do without the Intelligent Brake unit, but you will lose regen. If you bring in the IBU, it remains to be seen whether you can forgo the hydraulic side and use the hydraulic brakes and master cylinder from the host vehicle, or if you really have to adapt the Leaf brakes into the host.

Rob
 
Looks like I got lucky! Bought a wrecked 2012 w/24k miles from Copart/Autobidmaster. Ended up being just under $7k with fees and shipping from WA to AZ. Looked promising, but you can never really tell what you are going to get with these salvage auctions.
http://www.copart.com/us/Lot/20215745/Photos?SearchId=0" onclick="window.open(this.href);return false;

Leaf arrived today, had low battery warning and 6 miles range remaining, but started right up and drove off the truck. Small number of minor DTCs, after clearing with LeafSpy no DTCs reappeared. All fluids seem to be holding level (coolant, etc), AC works fine. Printed a temp permit and drove (very slowly) to Nissan dealer 3 miles away, still showing 6 miles range. Tried level 2 charging, started right up at 3kW. Switched to QC, charged to 80% (49-188 GIDs) in about 40 min at 17-18kW. Battery showing 11/12 capacity bars. Drove to work with AC (~10 miles, 92F) with no issues, glides well, brakes straight, no wheel pull or vibrations. Still no DTCs after drive, ~60 mile range still showing and average >5m/kWh for the trip. Pretty jazzed!

Should be able to start testing out some of this theory on real hardware now!

Rob
 
Here are a few pictures of the current state of my Leaf ;)

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Still runs, drives, and charges :)

Next step is to drop battery, rewire into 2x24 module packs, and temporarily re-install it back into the Leaf interior to test.

Rob
 
Battery rewired into two 24 module packs using a second set of stock rear pack bus bars, mounting plates and bolts, with the modules and bms looms from the front left/right sub packs.

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Back up on jack stands, front seats out, floor cover coming out next so I can cut an access hole into the passenger footwell to pass the HV connector into the passenger compartment. Then will reconnect the re-wired battery inside the vehicle to make sure everything still comes up correctly, and proceed to testing on removing more controllers to simulate the final installation in the host vehicle.

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