After flying this morning I was doing some repairs and all of a sudden i heard a pop and smoke started pouring out of a Flightmax 3s 1300. I had not flown that pack. I just brought it home unflown. It was just sitting in the concrete block I store it in. I have a bucket of sand on hand that I dumped into the block and put its concrete top on. Smoked like crazy. Stunk up the cellar. There was another 1300 in the same block. The voltage on that measures fine but I don't know if the heat from the venting pack up against it might have damaged it? Now I am a little wary ofmybatteries. I treat them well. Have only charged them at 1C and do not abuse them. I recently balanced the pack. That was a small 1300. I recently got 6s 5000's.