I have a 2000watt - 4000watt inverter that I am running off one group 31 battery. The problem I'm having is the inverter shuts off at 11.5v which doesn't give a lot of run time before it shuts down. My thought was to run 2 batteries in series to get 24v and step the voltage back down to 12v. Anyone know where I can find a 24v - 12v regulator with an output of about 150 amps or done something similiar? Thanks