Gene,
The only documentation I found is on the meter itself - nothing on the switching for different batteries. Meter reads 10V-16V and Percent Charge. The paper is full of good info, such as a) connect + to + and - to -, and b) "Crimp lug after inserting wire". Curiously, it's a 12V meter but the paper shows it connected to a 6V (3 cell) battery?