12v batteries
HEY BENWD YOU HAVE TO USE A BATTERY ISOLATOR .ALL DUAL BATTERY SETUPS SHOULD HAVE THAT, MY TRUCK IS FACTORY INSTALLED . ISOLATORS ARE AVAILABLE AT AUTO PARTS STORES , SOME RV SUPPLY STORES . YOU RUN YOUR CABLES INTO THE ISOLATOR AND OUT TO THE BATTERIES . THE ISOLATOR SEPARATES THE TWO BATTERIES ,ALLOWS CHARGING,AND USE OF EACH BATTERY BUT NOT DRAWS FROM BATTERY TO BATTERY. AS I SAID EARLIER ITS BEEN AWHILE SINCE I DID A DUAL SETUP, THAT WOULD HAVE BEEN FOR THE LOCAL FIRE DEPT, WITH THOSE WE USED A BATTERY CUT OFF SWITCH ALONG WITH THE ISOLATORS . TEAM3360