My controller is a Magnetek Model 6332 with "Option C" which my manual says "contains an automatic solid-state Battery Charging Section. When 120 VAC power is connected to Power Center, the Charging Section will automatically sense the condition of the RV battery. If it is below full charge, the Charging Section will start charging the batter." So does that mean as smkettner said, I can leave the controller off as long as my batter is 12.2v or better? I have a switch devoted to the controller. And my thinking is no sense is using something if I don't need to. Looks like I dodged a bullet on the battery boiler seeing as my rig is 20 years old and a Toyota.