Victron energy MultiPlus 12/500/20 Manuel page 8

Charger only
Note: the Multi will shut down if four abnormal events occur within 30 seconds.
The Multi can be reset by switching to Off and then to On.
8
On / Off / Charger-only switch = Charger only
The AC input voltage is switched through and the charger operates in
bulk or absorption mode.
On / Off / Charger-only switch = Charger only
The AC input is switched through and the charger operates in float or
storage mode.