If you fly very seldom each year ? like only 20 times in nice weather ? I do that. 2 years & ALL LIPOS start to slow puff up. LOTS of money for a little flying. I use a FMA balancing & storage faithfully. LIPO …….. DOES NOT LIKE LONG storage charges. No use all of winter rarely spring or fall. I believe that is what PUFFS them & makes them dangerous afte a few flights.
My A123 LIFEPO4 cells love that treatment. The ones in the B & D vacuum cleaner go down to 5% or less every week. many years on the 90 % pack. There isno danger with LIFEPO4 by A123 company. Do NOT buy the cheapy LIFEPO4 they are crap & will just vent all the life out of them. A123 or nothing else. Best sport flying battery. Each battery is about 3.6 right off the charger. I run them down to a slower WOT speed. Then charge at 4 amps. Both sizes.