It is funny how opinions/experiences vary on any subject but batteries and how long they last is one subject with a lot of differences. I think it obviously all depends on what and how you (we) are using them. The above post seems to state that on-board charges are THE PROBLEM but I think my on-board charger is what has helped to prolong my battery's life.

My G3 came with Deka marine batteries when I bought it in June 2000. Within a month I installed a DUAL PRO on-board charger and I keep in hooked up and working whenever the boat is not on the road. I was told by the owner where I bought my boat that, unlike most on-board chargers, the DUAL PRO turns itself on and off (once the batteries have been fully charged) rather than providing a continious trickle charge. Apparrently this prevents overcharging and boiling of the fluid.

Anyhow,in April of 2005 I bought new Deka batteries. I think FIVE YEARS pretty good for batteries, so I'll keep using Deka and DUAL PRO.