intermittent charging error

intermittent charging error

I have a nema 14-50 charger at home with 50 amp circuit. At times my model S will charge great, but almost every other night it charges intermittently - on for about 20 minutes then off for 40 minutes, then on for 20, off 40, etc etc. I have this documented because we have the PG&E home monitor which shows either continual charging or a saw tooth pattern of on / off / on. I replaced the charger cable and that didn't fix it. Anyone else have this? Any ideas? THANKS!

george210 | December 25, 2012

this is truly troubling. Given that electrically charging is the only way to ensure range.

Brian H | December 26, 2012

A circuit overheats, breaker opens, cools, closes until it overheats again, etc.

hoffscot | December 26, 2012

Thanks Brian. Seems appropriate. Would that be a car issue or my home system issue?

Theresa | December 26, 2012

Was the car nearly fully charged? I have not watched mine that closely but when it is full the charger turns off but due to the power drain I have noticed it turns on occasionally but I doubt it is that often.

stevedar | December 26, 2012

Check out the lights on the mobile connector. Troubleshooting section of the mobile connector describes the meaning of various flashing red light combos. The guide is available from the manuals link in your garage if you don't have a hard copy.

Brian H | December 27, 2012

Almost certainly a house issue, unless it happens every time on other chargespots, too.

dtich | December 27, 2012

two thoughts:

1. it's obviously not tripping a breaker, otherwise you'd have to manually reset... it may however be sensing high resistance in the circuit and limiting charging to keep wires from overheating. what gauge wire did you wire the 14-50 with, and how long is the run?

2. this may actually be normal charge behavior under certain circumstances, for the health of the battery. i don't know, but i don't think most users out there have monitored the entire charge cycle of their car so closely...


sergiyz | December 27, 2012

Sounds like an issue with built-in chargers or battery cooling system.
I'd call Tesla.
Does it actually use all 50A or is it 40A ?
It seems to be capped at 40A for NEMA 14-50, at least with the older firmware version.
Still, the charging has been very stable for me, no interruptions.