2015 Gem Car shutters when put in reverse

Took my Gem car out this afternoon. Stopped at a stop sign and everything went dead. No electrical power. The BMS blue tooth showed all of the batteries were up to capacity. Shortly afterward the electrical power came back on. I had, seemingly, full throttle in forward but when in reverse the car moved but would shutter. I do not believe that it is the batteries or fuses. Any ideas?

This is the car that I just, 100 uneventful miles ago, 25/205ah lifepo4 batteries in. It has a Daly 25s/250amp BMS that I ordered custom-built directly from Daly. I have since done a manual voltage check of all 25 batteries and they are OK and within .025 volts of being perfectly balanced. The shuttering in reverse seems to be the only thing wrong at the moment.

Motor, controller, spline, half shaft ?
Don’t know how to narrow it down. Any codes?

Thanks for the reply. No codes and no problems that I notice. Goes great in forward.

You might reverse the field wires to see if problem stays with reverse selection going forward.
If it does it’s a controller issue.

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Field wires? If it not in the battery compartment or the engine I do not know how to do this.

The two small wires on the controller or motor. This will make motor run backwards.
So the reverse components in the controller will run move car forward.
If car is still ok going forward something mechanical is a problem. Brushes or such.

Hi, Thanks, I will try that this morning.

Reversed the wires on the motor and the car will go backwards, with the car in reverse, just fine now, however when I put the car in forward it still goes backward and the shutter is still there.

Can’t follow, sorry.
@AssyRequired can you interpret?
Now it goes forward ok when in reverse?
Goes reverse with shutter when in forward?

Then it’s mechanical, suspect stuck brushes.

You might reverse the field wires to see if problem stays with reverse selection going forward.

This was my first thought.
Reversing the field wires will make the car run opposite of the selector switch. Real easy to do it off the controller. It’ll probably go “Beeeeee” when in forward now as the controller thinks it is in Rev.

While you are under the hood look for any loose wires that may be moving around. Give the motor a lift to see if something is coming loose in the driveline.

Describe the power drop event again with a bit more detail.

  • You say all power went dead but you still had your BMS still active? Does that normally go ON/OFF with your key? (or is it powered separately?)
  • Did your display go out also?
    What you are describing sounds like a bad keyswitch event. Having a big wad of keys hanging might be switching off your car as the pendulum swings forward when you go backwards.

Power went dead, all display dead. When back home turned the key back on and the power came back. BMS gets it’s power from the pack. That is when I checked the BMS to see if it was a battery problem. As before no signs of a battery problem 84+ volts across the pack and each lithium cell balanced at about .025 of each other. No big wad of keys (had that happen before). Switch seems to be working as it should. No loose wires and the motor is tight.

Did not have the shuttering problem before.

I agree with Inwo. This is a very confusing statement. Please verify that you are not mixed up with your description.

When I apply my wife translator* this is telling me- (*which gets me into trouble quite often)

  • You reversed the Field wires
  • Goes Backwards smoothly now when switch is in forward
  • Goes Forward now with stutters and jumps.

If this is true then I would have a look at the controller.

If this is NOT true then clarify and also tell us what wires you switched, or did you switch them back?

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Goes backward fine with the switch in forward. Goes backward with the switch in reverse but shutters. This is with the wires on the controller reversed.

Sorry for the confusing message before. I reread it and even I was confused.

I think you just did it again? :stuck_out_tongue_winking_eye:

Seems clear to me this time. What is it that you are asking to be cleared up?

  1. Wires on controller reversed.
  2. Switch in forward Gem moves in reverse just fine.
  3. Wires on controller still reversed.
  4. Switch in Reverse Gem moves in reverse with a shutter.
  5. Wires on controller on normal poles.
  6. Switch in forward Gem moves in forward just fine.
  7. Switch in reverse Gem moves in reverse with a shutter.
  8. No sign of Gem power shutting off.

I share his confusion. It’s not you it’s us. What you stated was perfectly clear. It is just not possible. :slight_smile:

I believe you. I also believe you stumped me. Sorry to doubt your well worded description.
Need to draw this out and give it some thought. F&R moves car in the same direction. That’s crazy talk. :slight_smile:

Ok, first test the motor for leakage to ground or field to armature.
All wires to motor disconnected.
Megohm scale.
Any wire to frame = near infinity.
Field wire to armature wire = same infinity.

And none of what you reported threw a code?

Going to the local Gem dealer this afternoon and pickup a new switch to try.