I just bought one. Sometimes there will be days or even a week or two before I can get to a field, so Voltwatch will tell me if I need to charge; keeping the batteries charged all the time will create "memory" from what I am told-If you keep the batteries charged between 3/4 and full all the time, the batteries will think that that is all the capacity they have. Voltwatch will give me a better idea of where I'm at.