The Hella Marine two-group light dimmer offers precise light regulation for 1 or 2 separate light groups as well as an electronically controlled "soft start" automatic which slowly brings the bulbs up to their operating brightness during their sensitive warm-up phase, thus ensuring a significantly longer service life for the bulbs. In addition, the built-in automatic switch-off prevents excessive discharge of the battery when the voltage is low. If the voltage drops below 9 volts (for 12 volt systems) or 18 volts (for 24 volt systems), the lamps are automatically switched off. As soon as the voltage rises above 9 volts again, the lamps can be switched on again. If the batteries are charged, the voltage in the mains may rise up to 14.4 volts (for 12 volt systems) or 28.8 volts (for 24 volt systems), which can extremely shorten the life of the bulbs connected to the mains. The two-group light dimmer therefore reduces overvoltages to standard voltage.