Charging Fails. Battery Too Hot. What's Happening Here?
I was at an EVGO station today and had a first take place in my 5 mos of ownership. After two or three minutes of charging at 110A (GOM showed 60 miles of range) the charger stopped, displaying a CHARGING FAILED, BATTERY TOO HOT message.
It was probably the hottest day I had ever fast charged the car. Ambient temps were into the 90s. Torque showed battery temp around 95F.
I reset the charger and repeated. Same error. OK. Now had 90 miles of range so I drove to another EVGO charger (there was only one station available at the location where the error occurred). Ambient was down to 69F. Battery temp was only slightly cooler at around 90F. Charging session went fine. No errors (100 amp charge, which was charger's max).
But now I'm wondering what the anatomy of this problem was. I tend to think it was a problematic charger, but I have no knowledge of what data is shared between the car and the charger at a DCFC. The charger seemed to be acting like it got data from the car that that the battery was too hot and to shut down. First, is that level of telemetry possible? If so is it using the J1772 protocol to pass the traffic? Wait. There MUST be a data exchange. At least one way (car to charger) because charge rate is based partially on battery temp. Not to mention SOC. Right?
But if so, why didn't the car simply tell the charger to slow the rate of charge?
My best guess therefore, since the subsequent charger worked in similar conditions, is that, YES, the car can tell the charger its battery is too hot, but in this case the charger may have read a signal that the car had not sent. I mean the battery temp (which I've never paid much attention to) was still 86F later on when ambient was 59F.
Can anyone either confirm my theory or cure my ignorance?