Are there any tips for safely cooling down a battery before charging it back up? I have two batteries and plan flying more than what would available on two full charges. I don't want to damage the batteries by charging them while they are still warm. Are there any tips for cooling them down faster without damaging them? I was thinking I would just put them in a cool that had one of the little frozen packets. I don't want to freeze them, have them be in 50 to 60 degree air instead of 70-80.