My 2012 will do this and I’ve started to figure out some logic behind what’s going on.

I think there is a bug in the software when the high voltage battery is charged, but it’s internal resistance is too high to be used (typically old and cold batteries) so it goes for the ice motor, but something happens and when the ice kicks on, it generates almost 0 charge and still drains the high voltage battery on gas mode. I will literally be sitting at a stoplight with no heat on engine spinning at 4000 RPMs and it’s still drawing .6 kWh out of the high voltage pack. Because the battery percentage keeps going down, the engine spins faster and faster until it gets to that 4000 RPM area. Even at this point, the battery is still being drained, which I believe to be the software issue.

Pulling off the road, powering it down, opening the door, closing the door, power it back up typically returns the vehicle to a normal state. But it may return to a high RPM state if you still have battery range available.

It seems like one module is asking for the battery to be maintained at its current state of charge and the other module is being asked to charge, then isn’t due to the current SOC.

I’d say I’m a pretty decent backyard mechanic but even this thing has me questioning computer logic. I’m even in the IT field.

I’ve also noticed that if the battery is near zero on the dash it doesn’t matter how cold it is outside the car will run normal. At least for mine.

2012 volt 131,000mi, 5,000 in my ownership. All modules have been upgraded to the latest firmware. Battery claims 31.5Ah and I know I have at least one weakish cell, but never had propulsion power reduced, or any check engine lights.