Right now I am in kind of a dilemia about hooking up this battery power supply correctly. As you can see in the picture the batteries are connected in series and parallel so 12v and 24v are outputed. Will noise from the AC line come in through the batteries if I keep the ground connected all the time from the charger to the batteries ? Should I use a different switch than the DPDT switch? Just look at the picture and give me the best options in connecting two 12v batteries to output 24v and 12v while having a switch to connect a 12v charger. Thanks a bunch for your help. I appeciate it.