I have to agree with Hotboat. Any charger that does a Constant Trickle charge is not good for the battery, it can boil a battery. If you want an inboard charger do what 28elim. did, that charger shuts completely off when the batteries are at full charge. I would leave it plugged in for a couple days and then unplug it and would do that every couple weeks. Kinda makes be nervous to leave it plugged in all the time but thats just me.