Alright, let's get started - first minor issue. I will diagnose further this weekend but curious if anyone has run into this problem.

The volt gauge on my H1 reads 12-14 with the ignition off, when you start the truck - it is off the chart. The previous owner just put in brand new batteries, not sure if that has anything to do with it?

Any suggestions on where to start?

 

assume that means high volts ,huh?

that means out of control generator,putting out max,high voltage.
it probably fried the other batts so he put in new ones which you will fry if you run it very long.

the 12-14 is normal when off,the batt cant put out any more no matter how much it is overcharged when running.

you should not run it until it is replaced. the generator,or control system.