This charger is a good deal and works fine:
This is the battery I use:
I also have some "Blue Lipo" but I haven't used them much and don't know how they will last.
As a side note, a RMG winch uses way less battery power than an arm winch because once the RMG is in a position it doesn't require any power to stay there while an arm winch must use power to hold it's position.
I just had to find out if water really is an enemy of LiPo batteries so I took and an old battery and threw it in a bucket of water....nothing happened. The FAA says to use water to put out a fire if a cell phone or computer catches on fire, they use Lipo batteries too.