Hi all - my wife and I bought a 1982 Carver Mariner late last season. We replaced the house batteries this spring ( 4 - 6 volt batteries in series / Parallel ). The boat has an original Pro Mariner 30 Amp Charger ( 3 bank - Ferro Resonant ). We have been on shore power since going in the water 2 weeks ago, when I turn the charger breaker to "on" - I can see the Amperage meter on the charger go from zero to maximum then back to zero , a few seconds later the same behavior zero to max then back to zero. This doesn't seem normal to me - any ideas on how or what to check ? I did check that the single ground wire is attached to a good ground and that the Positive wires from the charger and proper hooked to a Positive post in the 4 battery house set. I am at a loss on how to check further to see if the charger is charging.

Thanks in advance