I have two battery system to switch between battery 1, all, or battery 2, I have verified both batterys are good. The only way that I know of to see if the batteries are charging is to put a digital voltmeter on the pos and neg post of the battery one battery at a time and at idle check the voltage 11.5 volts and then take the engine rpm up to 2,000 rpm and check the voltage again to see the following reading CHANGE. 11.5 then goes up to 11.9 volts for around 2 seconds or so. You also need to know that I had to do this while the batteries were LOW on voltage. I have NOT checked the system with the batteries fully charged yet. I dont have a book on the system. Any help or specific tests to do to figure this out would be appreciated. Thanks!