10 January 2010

Dogged the cold "bullet"

Drove to work last Saturday, the first time I have driven very aggressively in the Mini E. On arrival I had 15% charge left, batteries up at 90 degrees F, and the forecast saying ten degrees expected that night.

Plugged in the car on the slow charger, but with only a few hours at work and much lower charge than usual, it was clear I was leaving the Mini E over night and driving my gas car home for the 65+ mile drive.

I left my 900 watt 120 volt accessory cabin heater on the timer to run 30 minutes on and 30 minutes off all night. But I did not have a good feeling with the low temperature forecast. So I went back on Sunday and sure enough, it had stopped charging at 40% and did not want to start charging again.

Driving around the parking lot, I had the symbol with the thermometer in a gear on the dash. The book says that means the battery is too hot (there was no regenerative braking) but I think it also comes on when the battery is too cold. The dash display said 56 degrees F but someone says that is the warmest battery pack, I suspect some packs were too cold to charge.

When trying to restart the charging, the car would blink several times and then the safety box would cut off with a slow blinking red light. I think it was labeled "charging fault" but I did not pay much attention.

I turned on the built in heater AND plugged in the 120 volt accessory heater full time, and for a while I aimed the accessory heater straight down the vents to the battery packs, switching back and forth between the two vents.

After this heating, the charging would start and kept going for over an hour. The battery temperature on the dash display came up to 59 degrees. So I went home, leaving the accessory heater running full time all night in the Mini E. I'll see if the car is still charging in the morning.

I knew when Mini said you have to have a garage for this car, they meant it. A prototype with an air cooled battery is not up for New York Metro area winters outside. I was afraid I was headed down the path that some others have reported with a hard failure and weeks with no word from service. Maybe I still am, tomorrow will tell. But next time I leave it outside on a cold winter night, the accessory heater is staying on full time. Part time is good enough for in the garage only.

But I am completely confident that the production electric cars with liquid based temperature regulation for the battery will not have this problem even parked outside.

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