when ours is on hard standing I use portable gen for power tools etc and have the other socket plugged into the boat shore power to charge up the batts, it would be on for 5 or 6hrs at a time, so how long it takes I couldn't answer, but as previously stated the last bit of charge takes quite a bit of time, I would think a lot more than 1 hr. at work pair of truck battery's, which is the same as fitted to boats around 140ah each would be on charge overnight. so around 12hrs.