I have a 110 converter In my truck, this simplies things as everyone has the 110 charger. And I have left It on all day and there's no problem starting the truck when I leave. One word of caution DO NOT charge them Inside the cab, as they will really ruin a seat In short time, and yes I speak from experience !! And the discharge thing, per my experience discharging bats, I used a 12 volt headlight for this and I ruined 3 bats, I have read all kinds of stuff on bat memory, etc. and well the results was'nt what I was looking for, and I did'nt run the bats all the way down. So maybe they were just about wore out already or my lucky streak prevails. Hope this helps as to what not to do !!... I know this does'nt answer your question, but at least you should'nt take the path I choose.... :?