Re: how to tell if engine is charging batteries?
Just a couple of technical facts to ponder over: Electical current is described as the flow of electrons from atom to atom, in a circle (circuit). In the case of a battery, the electrons flow out of the negative terminal and return to the positive terminal when it is supplying power to a load. The guts of the battery are part of the circuit and the electrons are passing through it. (Yeah, I know, that theory is hard to grasp.) But anyhoo, when the battery is being charged, the electron flow is reversed through the battery---in the negative and out the positive. To make those electrons go through backwards, the charging supply voltage has to be greater than the battery voltage. THAT is why a battery under charge will show a higher voltage than one just sitting there, not being charged.
More to ponder: Without gettng into details, the battery voltage while under charge rises slowly as the battery takes on a charge. That is why it takes awhile to reach its max. Regulated charging systems limit the charge voltage to a design value. Unregulated charging systems just keep increasing till factors such as resistance eventually limit it.
