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Discussion Starter · #1 ·
I have been working on a full Leaf (2014) transplant into a 1975 BMW 2002.

The status is:

  • Purchased 2014 Leaf (26,000 km on the clock) - wrecked but working
  • Removed all the non essential bits (per other posts on this forum)
  • Demonstrated "minimum" set of components where the Leaf still worked (all the parts in the old body)
  • Removed "minimum" set of components outside the vehicle
  • Rebuilt components on bench

The gearbox was removed (but I kept the parking brake actuator). The steering alignment sensor & indicators were attached. The original battery was used (not disassembled).

I am very pleased to say that the system started & I was able to change to D and also R. It would, however, not change back to P as the motor was still spinning.

I was not able to stop the motor spinning. I had to resort to removing power (12 V and the main battery).

Has anyone else had this issue?

I don't have the ABS & Brake computer - could that be the issue? I was surprised that removing the 12V power did not stop the motor. I needed to remove the main isolator battery to stop it.

Leaf spy was communicating although did not seem to ready the battery status.

Help!

120650
120651
 

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I have been working on a full Leaf (2014) transplant into a 1975 BMW 2002.

The status is:

  • Purchased 2014 Leaf (26,000 km on the clock) - wrecked but working
  • Removed all the non essential bits (per other posts on this forum)
  • Demonstrated "minimum" set of components where the Leaf still worked (all the parts in the old body)
  • Removed "minimum" set of components outside the vehicle
  • Rebuilt components on bench
The gearbox was removed (but I kept the parking brake actuator). The steering alignment sensor & indicators were attached. The original battery was used (not disassembled).

I am very pleased to say that the system started & I was able to change to D and also R. It would, however, not change back to P as the motor was still spinning.

I was not able to stop the motor spinning. I had to resort to removing power (12 V and the main battery).

Has anyone else had this issue?

I don't have the ABS & Brake computer - could that be the issue? I was surprised that removing the 12V power did not stop the motor. I needed to remove the main isolator battery to stop it.

Leaf spy was communicating although did not seem to ready the battery status.

Help!

View attachment 120650 View attachment 120651
Hi! I don't have the entire Leaf infrastructure, so I may not be that much help to you. Here's what I know about my 2014 Leaf motor/inverter. The assumption seems to be that if the motor is
above 400 RPMs, letting off the throttle means maintaining that RPM. If the motor is below 400 RPM's, the motor will coast to a stop. If you wish to slow the motor down, the command for negative torque must be given to the slow the motor down below 400 rpms. Depending on the can bus you are attached to you can see the torque command being send from the VCU to the PDU.
The torque command Can ID is ID4 and is sent every 10 ms to the inverter. I don't use the VCM portion in my application, so I don't know how the throttle is handled. I'm guessing regen is off due to the brake computer being gone. Without regen, the motor won't get a negative torque and won't slow down once its gotten above 400 rpms.
 

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The assumption seems to be that if the motor is above 400 RPMs, letting off the throttle means maintaining that RPM. If the motor is below 400 RPM's, the motor will coast to a stop. If you wish to slow the motor down, the command for negative torque must be given to the slow the motor down below 400 rpms.
Does it really "maintain RPM", or does it just run at zero torque? With no power or regen, and nothing connected to the motor shaft, it will spin for a long time. In an complete vehicle this situation never occurs, because there is no neutral and the motor is never free to spin.
 

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Discussion Starter · #4 ·
Hi! I don't have the entire Leaf infrastructure, so I may not be that much help to you. Here's what I know about my 2014 Leaf motor/inverter. The assumption seems to be that if the motor is
above 400 RPMs, letting off the throttle means maintaining that RPM. If the motor is below 400 RPM's, the motor will coast to a stop. If you wish to slow the motor down, the command for negative torque must be given to the slow the motor down below 400 rpms. Depending on the can bus you are attached to you can see the torque command being send from the VCU to the PDU.
The torque command Can ID is ID4 and is sent every 10 ms to the inverter. I don't use the VCM portion in my application, so I don't know how the throttle is handled. I'm guessing regen is off due to the brake computer being gone. Without regen, the motor won't get a negative torque and won't slow down once its gotten above 400 rpms.
As I am using the OEM systems it appears there is no opportunity to apply negative torque. I actually noticed the before I removed all the parts from the car i.e. I needed the hydraulic brakes to stop the car when it was in forward and reverse.

I don't recall seeing this problem in the few videos of benchtop Leaf systems. I was also surprised that the computers kept going even though I removed the 12V power.

Perhaps I plug in the ABS & brake booster to see if it behaves in the same way?

Does it really "maintain RPM", or does it just run at zero torque? With no power or regen, and nothing connected to the motor shaft, it will spin for a long time. In an complete vehicle this situation never occurs, because there is no neutral and the motor is never free to spin.
Yes it seems I got caught by not having a complete vehicle - as the VCM probably assumes rightly that you only drive a car if it has brakes! My incorrect assumption was that "no accelerator" and "brake" would stop power to the leaf motor (note I was using the standard Leaf brake/ accelerator pedals with has a switch to say if the bake is on. The hydraulics were obviously removed).
 

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Does it really "maintain RPM", or does it just run at zero torque? With no power or regen, and nothing connected to the motor shaft, it will spin for a long time. In an complete vehicle this situation never occurs, because there is no neutral and the motor is never free to spin.
Hi Brian! I don't have the machinery to load the motor down and see if it really maintains. (yet) In the 'forward' direction. The motor will actually speed up slowly, despite giving a 'zero torque' command. This is free-running with no trans-axle. In reverse, it maintains speed and might drift a little. When power is cut, the motor slows down at a reasonable rate.
 

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As I am using the OEM systems it appears there is no opportunity to apply negative torque. I actually noticed the before I removed all the parts from the car i.e. I needed the hydraulic brakes to stop the car when it was in forward and reverse.

I don't recall seeing this problem in the few videos of benchtop Leaf systems. I was also surprised that the computers kept going even though I removed the 12V power.

Perhaps I plug in the ABS & brake booster to see if it behaves in the same way?



Yes it seems I got caught by not having a complete vehicle - as the VCM probably assumes rightly that you only drive a car if it has brakes! My incorrect assumption was that "no accelerator" and "brake" would stop power to the leaf motor (note I was using the standard Leaf brake/ accelerator pedals with has a switch to say if the bake is on. The hydraulics were obviously removed).
I think the most common videos that you may see with leaf motors have some type of other controller, either a board from openinverter.org, or like myself, sending CAN commands via some software. The Leaf software may depend on the wheel speed sensors to determine when to perform regen. If you wish direct control, Dala has a board which can play 'man in the middle' with the CAN bus and you can force regen.. ;)
 

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I've got a 2012 system and what I saw when powering my system without anything connected to the output was the following:

The motor would burst up to maybe 500rpm then coast down for a second or less, then burst up to maybe 1500 rpm and coast for a second, and continue to pulse to higher and higher rpm. There was no way to stop this other than to disconnect the power nd it is disconcerting.

When it is connected to a drive system and you lay off the brake the car will creep, like a normal ICE vehicle.

It therefore seems that the motor pulses when no load is detected, and this is probably not great for the motor if you let the rpms get too high, but...when there is a load connected the motor does seems to spin at a steady rpm.

Having no load on the output probably confuses the PID or PD motor feedback loop causing it to behave this way.

Hope that helps!
 

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I was also surprised that the computers kept going even though I removed the 12V power.
I've seen this happen too and I suspect the lingering power might come from the e brake capacitor which is the black box in the back of the car. It dies eventually but is also disconcerting. Unexpected shutdowns of the leaf system are not elegant!
 

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Discussion Starter · #9 ·
I've got a 2012 system and what I saw when powering my system without anything connected to the output was the following:

The motor would burst up to maybe 500rpm then coast down for a second or less, then burst up to maybe 1500 rpm and coast for a second, and continue to pulse to higher and higher rpm. There was no way to stop this other than to disconnect the power nd it is disconcerting.

When it is connected to a drive system and you lay off the brake the car will creep, like a normal ICE vehicle.

It therefore seems that the motor pulses when no load is detected, and this is probably not great for the motor if you let the rpms get too high, but...when there is a load connected the motor does seems to spin at a steady rpm.

Having no load on the output probably confuses the PID or PD motor feedback loop causing it to behave this way.

Hope that helps!
Thanks and appreciate the experience you had. In some ways, I am pleased it was not just me. As don't recall reading about this issue it is good to share - so that the next person does not fall into the same trap.

I've seen this happen too and I suspect the lingering power might come from the e brake capacitor which is the black box in the back of the car. It dies eventually but is also disconcerting. Unexpected shutdowns of the leaf system are not elegant!
I don't have the brake systems connected so I will see if I can remove the brake backup capacitor now. I am reasonably certain I can remove a couple of more parts from my minimum running set. Thanks again @eBIMMER.
 

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I'm not building an EV yet, but I own a Leaf and I can tell you that this issue probably comes from Nissan programming the Leaf to "creep" like an ICE car does. It will never come to a complete stop, even with not torque request. I would imagine removing the load from the drivetrain would cause all kinds of feedback loop issues and explain the problem you're seeing. Ultimately, this is a "bench" issue and not a problem you'd have to deal with once it was installed in a vehicle.
 
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