Some of the very best maintenance type chargers are the on board boat chargers. Rugged, waterproof, dependable. They can be bought for 1,2,3,or 4 battery system. I have one ( 3 battery set-up) on my boat that has been on it for almost 5 years. I check the water in the batteries once a year and don't worry about them. Because of the hunting season, I don't fish Oct thru Feb but I don't worry about the batteries being ready when I get ready to fish. I have the Cabela's model but the same charger can be bought cheaper from the company that makes them.
