its triple the charging system voltage (14 x 3 = 42). it was a system that was designed in the late 90's that they were going to switch all cars to (36v battery 42v charging system) kinda like they did when cars switched from 6v to 12v. thats the way it was explained to me when i had to go to all the hybrid training in detroit for gm. also its considered an intermediate voltage and easier for a normal tech to service with out blowing himself up.