Would be a good test for sure. Try batt #1, then batt #2 (in my case #2 is new), then try the setting for both batts simultaneously. Could check voltage results across the 3 different Perko settings. Thankfully I've not seen any indication of the low voltage issue, so can't really opine. I just needed the 2nd batt for the stereo and piece of mind really. Fig'd I was playing with fire by not having 2 and I never really trusted the jump box I hauled around at the lake. I was however able to rescue a couple stranded boaters with it which made it worth while.