I have searched for a simply answer to my question. I am a little confused. All I want to do is have a Li-ion battery pack that I will solder on to the car adapter plug. I do not want to charge the batteries from the Pro, I will simply charge from a remote charger. I will make sure the pack has PCB included. It looks like the voltage will be 14.8 due to the Li-ion characteristics. I am worried about voltage change with these batteries or actually any external power I may use. Does the circuit board in the pro protect itself from low, high voltage or amps? I am assuming it must to some level because a car battery depending on its state could have a large swing.