Hello Bridge100,
I have a multistage 16amp Ring charger. I'm not sure it makes any difference what brand of charger is used, providing it is multi stage, but the evidence now seems pretty convincing that a bank of fully fully charged batteries may give this misleading visual alarm, simply because of the method the unit uses to determine that it is charging efficiently from the alternator. Once some of the power from the batteries has been discharged, the warning light is no longer illuminated.