Vehicles with a two-battery system

Starter and system battery 

A two-battery system has a starter battery circuit and a system battery circuit. An auxiliary control unit monitors both battery circuits. Depending on the situation, the battery circuits are connected to or isolated from the auxiliary control unit via an cut-off relay.

Two AGM batteries, whose design and properties are described in AGM BATTERIES , are used as a storage battery.

Receiving/giving starting assistance via external start terminal 

The engine can be jump-started with an external voltage supply via the jump start terminal on the right side of the engine compartment.

Giving starting assistance via the jump start terminal is thus limited by the capacity of the starter battery when the engine hood/bonnet is open.

Charging starter and system batteries via jump start terminal point 

The starter battery is charged as a matter of priority with a charger connected to the jump start terminal. The voltage at the starter battery is the decisive factor in determining whether the system battery is also included in the charging operation. The auxiliary control unit automatically detects a charging operation at a charging voltage at the starter battery of ≥ 13.5 V. The cut-off relay is closed and thus the system battery is connected in parallel. Both batteries are now charged.

Prerequisite:

• Terminal 61 inactive
• Terminal 15 inactive

If terminal 15 becomes "active" during the charging operation, the cut-off relay is opened immediately and again only the starter battery is charged.

Trickle charging 

The increased standby current consumption can be compensated for via the jump start terminal point with the aid of the "Acctiva easy" battery trickle charger.