you wire the 4 volt battery in series with your 12 volt under your hood.then you run a power wire from upfront to the back 8 volt banks.your vehicle sees 12 volts like it should,and your system sees 16 volts.another option is a turbostart 3 post 16 volt battery,not sure if you could find these any more though,i do have one,but it doesnt hold a very good charge,i would throw it in for free to whoever buys these,you can always try to put new acid in the batt.powermaster makes 16 volt batteries,i bet they have an adapter,i'll look into that