Any A123 pack that loses more than 5% of it's capacity per year is junk, get rid of it. Also, genuine A123, as opposed to the foil encased LiFE packs are cylindrical steel case cells and will never puff, they are also vent before they explode. While there is no such thing as a 100% safe battery technology, genuine A123 packs come as close as anything out there today. I also use the FMA chargers and select 2.0C and they determine the capacity of the pack automatically during charge. I don't charge in the trailer as it's too inconvenient and simply charge at the filed while assembling the airplane. Rarely takes more than 15 minutes unless I had seriously drained the packs on the last outing.

Wayne