Battery Charging

If a normal or fast-charge unit is used to charge a battery, (e.g. Bosch SL 24 90, refer to BMW Parts), the battery must be disconnected from the vehicle circuit in order to avoid damage to paint finishes and upholstery by escaping gas.

Excessively discharged battery could be damaged or destroyed by the very high initial current (high temperature).

When using an electronically controlled charger (e.g. Siemens VB 80), the battery can remain connected.

the electronically controlled charger does not permit critical peak voltage.

An electronic charger also charges an excessively discharged battery with reduced current until a certain basic voltage is reached.


Caution: Always first measure open-circuit voltage before charging a battery installed in the vehicle. If the voltage is 10 V and less, it cannot be excluded that one or more cells are faulty or that the battery as a whole was already damaged on installation.

In this case it is always necessary to remove the battery, as escaping gas while charging could damage interior equipment. Attempt to regenerate
the faulty cells with low charging current.