Yesterday I hit something odd. I parked my Volt at work around 3.30PM with about 50% SOC, and hooked it up to the 120V EVSE using the same outlet as all other days. All seemed normal. When I got out at 7.15PM, the dash light was orange - something I had never seen before. The battery had picked up about 5% of charge. The EVSE had all lights green. And the MIL was on - another first.

I hooked up with Onstar, and ran a diagnostic. She reported "Li-Ion Battery Fault, service within one day" and "Voltec propulsion system error". Her advice was to just charge it at home and take it in if it doesn't go away - she said she had seen it before come and go.

At home, the car charged fine at 240VAC, but this morning the MIL was still on. When I plugged it in at work this morning, the 120V EVSE went from all lights green after attaching it to the outlet, to the top red LED doing a fast red blink when I connected the car to the EVSE.

Did my 120V EVSE throw in the towel? If it did, why was all green yesterday evening?

I scanned through my 15lbs of service manuals for anything comparable, but it appears that Onstar has more generic descriptions than the GM service manuals. AFAIK, there wasn't such a thing in the service manuals as a generic "LiIon battery fault".

The car drives normally on first sight.

Anyone seen this error before?