Do a forum search under BATTERY SITES and click on 12 volt
trouble by thread starter Chuck. I (Davidz71) posted some battery info and some websites that have great battery/battery charger info which explains different types of chargers. I use a 5 watt Solargizer solar charger/maintainer to keep up my state of charge but if I have used the batteries heavily on a trip and bring the TT home, I hook up my BatteryMinder to 110 v. power. It is a multi-level charger capable of charging 4 batteries at the same time. It desulfates (shakes the battery plates) to help solid material clinging to the plates fall off and mix with the liquid, charges, keeps a maintenance charge (floats a charge). It takes about 3 days to run the full charging sequence if I have run my batteries hard. You can leave the unit connected for years without fear of overcharging, boiling out water, etc. I no longer have the old univolt but a Magnetek unit was in its place when I purchased the TT. I do not let it run long if plugged into 110v.