DMC FW: PCS Current Offset Too Large warning - Error #1121

[dpeilow]

I've just seen this one twice. Once last night when I got home with a low state of charge (41 miles ideal in range mode on a 3.0 battery).

It happened again this morning when I got to work - this time the battery was at 63%.

Any idea what it means and if I should be worried? Some suggestion the battery is well out of balance - it has not been charged in range mode for 6 months and we are not sure standard mode balances it on a 3.0 now.

 

[PV-EV]

From my list: PEM sensor error. One sensor reading doesn’t agree with the other. Suggested solution? You guessed it, replace PEM. Maybe someone else has more info.

 

[petergrub]

Any idea what it means and if I should be worried? Some suggestion the battery is well out of balance

The current being measured is in the PEM at the Megapole Phases A and B. Those two Phases are used for regen charging and AC line charging of the high voltage battery. The warning is that the measured currents, that should be nearly equal, are starting to drift for some reason. I have resolved the error from a remanufacture of the PEM, but I don't know which part of the process resolved the error.

Also, the error comes from the DMC which resides in the PEM. It has nothing to do with the balance of the battery.

it has not been charged in range mode for 6 months and we are not sure standard mode balances it on a 3.0 now.

Range mode is the best way to initiate brick balancing. The bricks will bleed excess voltage while at or above 4V.

 

[dpeilow]

Many thanks for that Peter.

It happened again this evening.

I fully charged the battery in range mode, then immediately drove home. The state of charge was above full in standard mode. I intended to plug in again right away and set range mode on the VDS, but the car switched back to standard mode when I plugged in. Despite the ring immediately going to green, it still had time to throw this error.

 

[petergrub]

I fully charged the battery in range mode, then immediately drove home.The state of charge was above full in standard mode. I intended to plug in again right away and set range mode on the VDS, but the car switched back to standard mode when I plugged in.

Is there a need to range charge your Roadster? FYI, range mode really should be used on rare occasions as the higher state of charge puts extra strain on the battery and thereby reduces the lifespan. The firmware keeps a count on the number of range charges kind of how the ludicrous enabled batteries in the Model S/X keep a count on how many ludicrous launches the battery has endured.

 

[dpeilow]

Is there a need to range charge your Roadster? FYI, range mode really should be used on rare occasions as the higher state of charge puts extra strain on the battery and thereby reduces the lifespan. The firmware keeps a count on the number of range charges kind of how the ludicrous enabled batteries in the Model S/X keep a count on how many ludicrous launches the battery has endured.

It would appear that on the 3.0 battery it is necessary to balance it. It looks like that even a full standard mode charge doesn't balance the battery (which is different to the < 3.0 cars). I only do it rarely and often at times when I think there is such an issue. It actually just gained 1 Ah of CAC since yesterday.