Charger problems

[halo13]

Recently, my E-mag battery ran out, so i decided to charge it. After about 6min of driving in my car, the battery was charged. At the time, i though it was strange that the battery charged to fast. I shot the gun about 500 times, and the battery went out agan. My question is about the charger. when everything is hooked up, the light is red. A few min. later, the light turns green. I know the battery is not charged up all the way, but why is the charger giving me the green light?
So:

1.)Whats up with my charger?
2.)Can i get any old wall adapter? or do i have to get a special one? :cool: