A friend has a barge which has a Quattro 24v 5kva inverter charger (apparently professionally installed, certainly to a high professional standard), which intermittently swaps from "battery float charge plus sockets fed by shorepower" mode to "sockets fed by inverter and no charger" mode, exactly as though the shorepower had been disconnected (but the isolation transformer still hums, and the shorepower meter shows a small consumption, so it is not a shorepower failure) The status lights on the battery charger go out, and the battery bank starts to discharge. Eventually, it returns to charge/shorepower mode.
The load on the system is modest (typically about 500w max) and the shorepower current limit is set to 30A., so it's not overload...
Any ideas?