EVSE Charge Station

Yes, I call it a charge station. It is a charge station. Why not call it that. It's also electric vehicle support equipment. It is not the charger but a place to charge at. Like a train station is not a train but a place to go catch the train.

Pete :)

A bit more on the cold battery test

Well the test is over for the charging portion. After 7 hours and in the -37 degree F range the cell went to 3.650 volts and .2 amp charge. I used a spread sheet to help calculate AH into the battery over time. It is rough but good enough. After 7 hours it only allowed around 15 AH into the cell. I could not reduce the amps any lower and have the ability to check it. Even if I did there would be nearly nothing into the cell anyway. So after that time the cell went into hibernation and no longer really accepting a charge. The voltage at our target voltage of 3.65 was meet at .2 amp input. We only wanted to keep the cell at or below our target voltage as we would normally charge the cell.

I will test a discharge tomorrow morning for fun at those negative temps. I will measure temps and voltage after resting all night in the freezing condition.

I will then warm up the cell and do a charge and discharge again to see if any visible damage results from this freezing of the cell.

Here is what the cell looked like in the Ice bucket and another after we removed it and put it into the cooler with the ice and dry ice and all cooled and frosted.

Arctic Glacier Temp Charge Testing.

UpDate:

I am charging at this time.

Started the charge of the frozen battery. Our static information at the start of the test is as follows.

Jan 4 2012

2:51 pm

3.162 volts static

-2.9 F

---------------------

3.920 volts...........zero time...........20 amps.........-2F

3.808 volts...........:47 sec..............15 amps.........-2F

3.697 volts...........1:26 min............10 amps.........-2F

3.548 volts...........3:00 min............5 amps..........-2F

3.540 volts...........4:52 min............5 amps..........-2F

3.631 volts...........29:03 min..........5 amps..........-10F

3.630 volts...........44:20 min..........5 amps..........16F

3.650 volts...........50:15 min..........5 amps.........-16F

3.429 volts...........53:00 min..........2 amps.........-16F

3.410 volts...........56:28 min..........2 amps.........-18F

3.432 volts...........1:26:40 min.......2 amps.........-20F

So very cold temps will require being warmed so they can actually take a good charge. At this rate it will be well into tomorrow before the cell is charged enough. So an unprotected cell will require insulation and a warmer to keep it just above freezing so it can take a charge. According to the information here anyone with an Elcon won't be able to charge a pack because the pack will spike up higher than the cut off voltage and when the charger sees the voltage up that high it will shut off thinking its full. Ooooops.

So the cold forces the voltage to spike at normal amperage to above the recommended voltage of 3.65 volts. In keeping with our recommended charge algorithm it will be impossible for the elcon to charge unless the cell is above freezing. My two graphs show at a temp that is cold but above freezing.

The dry ice is keeping the cell from warming up and since the amperage is so low it does not have much chance to warm up. At least not until the dry ice is gone or the cell removed from the cold environment.

Any ideas about charging above the recommended voltages to force feed the cold cell? Think that might damage the cell? What we need to know is if I can like go to 4.6 volts and then taper off until I reach like 5 amps? Mmmmmm.

Pete