During driving, the starter battery is primarily charged. Once it is full, the secondary battery charger automatically switches to the secondary battery. Both batteries are then charged by the alternator. Up to a total voltage of 12.8 V, both batteries remain connected in parallel. If the voltage drops below 12.8 V, the secondary battery charger disconnects the auxiliary battery.

Additional consumers should only be connected to the secondary battery. Safe starting, even after longer periods of inactivity without charging, is ensured. It is ideal as a complement to solar systems. The solar panels and solar charge controllers can be easily connected in parallel to the secondary battery.

The electronics are suitable for all 12 V lead batteries. The charging current of an alternator is approximately 25% of the battery capacity. For example, with a 100 Ah battery, this means 25 A. This current is then distributed between both batteries when using the secondary battery charger. The switching capacity of the electronics is sufficient for batteries up to 500 Ah.