Jeff, Reset your inverter to cure your problem. Disconnect from all AC power (gen, shore), turn off the inverter using the rocker switch on the inverter, use your battery disconnect to shut off house power. Let it sit for a few minutes; restore power in reverse order. Had the mysterious clicking-thumping on my 05 Thunder, found the inverter reset procedure in the Beaver (not inverter) manual. Once reset, no more thumping and battery charging is back to normal.
Happy Holidays and Merry Christmas to all!!