Battery Types

[aread2]

Most 12v equipment (e.g. lamps, pumps) will keep working even if the batteries are flat, just becoming dimmer/slower. More sophisticated devices like fridges and inverters will stop working when the voltage falls below a set level e.g. 11v. either to prevent damage to the batteries or to themselves.

[Tony Brooks]

Sounds to me that either this is an inverter charger with a pass through mode so the shoreline can feed through to the boat's 240V circuit and you have turned it off or there is a selector switch (see label bottom right on inverter photo) and it is set to power the boat's 240V circuits from the inverter that you have turned off rather than supplying  them direct from the shoreline.

[cuthound]

It's a Victron Combi (inverter/charger). 

 

If you have only turned off the inverter part, the the charger will supply the 12 volt equipment provided it is connected to a mains shoreline.