mux said:You're blowing ever so slightly colder air over a battery case with poor thermal conductivity. There's not enough delta-T and not enough thermal conductivity to get much heat out of the battery that way. During a QC session the battery is producing between 1-2.5kW of heat, and the best you can do with 10C colder air is remove in the order of 100W or so. It's going to delay thermal throttling a little bit, but not much.
Did some grosso modo calculations on flat plate cooling using a cold plate directly below the battery case - with heat transfer material between the bottom battery case and the protector plate. BY NO MEANS AN EXACT CALCULATION. However as the film heat transfer coefficients are so low on the three limiting air surfaces, that - as mux points out - the cooling is extremely limited. It appears using a refrigerated cold plate below the battery - say on a garage floor that is 40 degrees Fahrenheit below the battery temp would only cool by a few oF over an entire night. I'm sure blowing air and adding radiation "cooling" to the calcs might add accuracy, but not likely change results - internal cooling is the realistic answer.
I am sure open to alternative proof of something that might work - I have a garage to experiment with and live in a very hot climate!