RE: 7.4v 8000mah balloning (slightly)
There are a few causes to a pack swelling....over amping, charging at to high a rate (I always charge at less than max...you say 8 I would go 6....It's easier on the cells) And always store cells at half of there capacity..........Again these are just some causes.......without all of the info I really don't know what caused yours to puff "slightly", Are you balancing the pck when you charge it?? Check the reading from each cell and see where they stand........