I have got conflicting advice from fishing buddies about batteries. Some say that if you run the battery all the way down, it will never completely recover. So keep it charged. Others say you should turn on the lights and deliberately run the battery down occasionally to prevent "memory failure". Who's right? Most of the batteries I have had to replace was my own fault. "Maintenance Free" does not mean never check the water level. They should really be called " Low Maintenance".