So today I started it up, before I did I checked both batteries and they were at 12.8/7
After starting the front one was at 13.3 with the bus idleing and the other was still at 12.8/7.
I disconnected them from each other and charged them both up off the alternator, which was putting out about 13.4.
If I turned the headlights on it would go down to 13 and if I put the fan on too it would drop to 12.8.
After charging them both up individually I connected them together again and they both read 13.3 while running the engine.
After killing the engine and checking after a little time passed they both read 12.9
Sooo what conclusions can I come too?
What's an acceptable voltage range from my alternator on both batteries while it's running?
Is 13.3 too low of a number, maybe a weak alternator? It seems even running just headlights it can't cover the voltage.