I have a all american rear engine bus . 2007 during a route the small wire came off the back of the alternator . It landed on the positive stud for the regulator and sent everything into overdrive . The amp and volt gauge pegged out . It destroyed the alternator . So I put a used alternator on the bus and fixed the melted wiring . Now the volt gauge reads 14 volts but the amp gauge is still running about a 100 amps . I have some basic knowledge about charging systems so this is a new one for me . Could it be gauge failure on the amps ? Or could the batteries be screwed up due to the failure of the first alternator ?
I would say replace the gauge first. We had a lot of issues with the amp gauges on our All American FE's. They would always read max or not at all. We had some that kept sweeping. Since they are not a requirement on our school buses here in Ohio, we removed them and filled in the spot with a cover. We had one mechanic spray paint the gauge black and disconnect it from the back this way the driver wouldn't keep writing it up.