Preliminary Information

Battery Care and Maintenance
Electrolyte level of present low-maintenance battery should be checked at
least annually and corrected to max. mark (specified by battery supplier) with distilled water when necessary.

Due to the increasing number of control units used in vehicles today,
discharging by the power consumption of control units even in standby mode is added to the natural self-discharging of a battery. the battery of cars in storage should be recharged at the latest every 6 weeks to maintain their service life and to avoid excessive discharging (refer to battery recharging calendar). the time for self - discharging depends on the car model and equipment.

Battery Charging
If a normal or fast-charge unit is used to charge a battery, (e.g. Bosch SL 24 90), 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. For safety, open seal plugs on each individual cell.


Battery Test
An objective statement on charged condition of a battery is only possible
via a load test with cold testing current. This test can be carried out with a battery tester, e.g.: Bosch T 12 220.

Refer to relevant Operating Manual for further details about the load test.

Acid density of a battery can also be used to determine charged condition. This check gives rise to uncertainty due to the design-related range of acid density, e.g. for charged battery: Acid density = 1.28 kg/l (tropic version : acid density 1.23 kg/l).

Another interference factor is the acid lamination immediately after filling with distilled water. Battery wear with partially sulphated and/or heavily contaminated plates will also lead to incorrect acid density test results.