I was wondering if anyone might be able to offer advice on an issue I'm
having with a Heart Freedom 20 inverter/charger. Here are the
particulars:

Heart Freedom 20
Model: 81-0205-12(209)
S/N 122228
Date: 1296

The unit works fine when the boat is disconnected from shore power. It
converts the 12 volts DC from four 100 amp gel batteries into 120 volt
60 cycle AC. When I connect to shore power (30 Amp 120vac), the
inverter switches into a battery charger and sends the ac thru to the
boat. (I think thru an isolation transformer). When that switch is
made (a few seconds after connection) the ac power and battery charger
goes out. After a bit (4 or 5 minutes), the ac and charger reset and
come on for another short period (4 or 5 minutes), and the cycle
continues. I tried disconnecting various loads to eliminate bad
appliances, but still have the problem.

Any help would be greatly appreciated. Thank you.

Joe