So the other night I had my P2 up catching the sunset. One battery is brand new and was fully charged, 2 others that came with my P2 second hand were showing 3 bars but wouldn't charge anymore. First battery was fine and flew for a little over 15 mins. Second battery seemed fine but flew for a bit less time. So I slapped the 3rd battery in, it was reading 66%, sent the bird up anyway and walked inside to get another battery (because walking away from your bird is a great idea). When I came back all seemed ok and I didn't pay it much mind. When I finally looked (this is after about 4 mins in the air) it was at 18% and I always start decending at 20%. I believe I was around 108m high and as I'm decending the battery life is dropping faster than a flaming P2 hit by a sidewinder missle. Obviously my blood pressure skyrockets and I try to get it over a grassy area fearing for the worst. Luckily I managed to catch it out of the air at 2% battery. So I got really lucky but would this be an indication the battery is soon to be no more good or could it be that I had them fully charged and let them sit for about a week because I couldn't fly due to rainy weather?