Wednesday, January 4, 2012

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.

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