Exhaustively Discharged Battery

Exhaustively Discharged Battery

• Batteries that have not been used in driving operation for a long time, for example in stored vehicles, discharge themselves.

• Batteries are considered to be exhaustively discharged if the no-load voltage drops below 11.6 V. In the case of extended downtime under 12.2 volts, the battery is prematurely damaged.

• Measure the no-load voltage in vehicles without a Battery monitoring control module (J367) or Energy management control module (J644). Refer to => [ Measuring No Load Voltage ] Measuring No Load Voltage.

• Perform a battery test with a Vehicle Diagnostic Tester if the vehicle has a Battery monitoring control module (J367) or Energy management control module (J644). Refer to => [ Battery Test with Vehicle Diagnostic Tester - ] Battery Test With Vehicle Diagnostic Tester -.

• With exhaustively discharged batteries, the battery acid (mixture of sulfuric acid and water) is mostly water, with a greatly reduced sulfuric acid content.

• Exhaustively discharged batteries become sulfated, i.e. all the plate surfaces of such batteries become hardened. Instead of being transparent, the electrolyte has a slightly milky appearance.

• The sulfating process may be reversed if an exhaustively discharged battery is recharged immediately.

• If battery is not recharged, plates will continue to harden, and ability to accept a charge will diminish. This results in reduction of battery performance.

Procedure

• The battery temperature must be at least +10 °C.


Risk of explosion on discharged battery with visual indicator.

• If the visual indicator has no color or is light yellow, the battery may not be tested or charged. Jump starting must not be used! There is a risk of explosion during testing, charging or jump starting. The battery must be replaced.


Risk of exhaustively discharged batteries freezing.

• Exhaustively discharged batteries freeze at low temperatures, the housing can crack.

• Batteries that have frozen must no longer be used.

Discharged sulfated batteries must be charged as follows using a low charging current:

- Adjust the charge current to approximately 5% of the battery capacity, i.e., the charging current for a 60 Ah battery is then approximately 3 ampere.

• The battery voltage must be at least 0.6 V!

• The (VAS 5903) battery charger automatically detects exhaustively discharged batteries and carefully starts the charging procedure with a low charging current. The charge current is automatically adjusted to the battery charge state.


Risk of damaging exhaustively discharged batteries.

• Do not rapid-charge exhaustively discharged batteries.

- Charge the battery. Refer to => [ Charging The Battery Using ] Charging the Battery Using (VAS 5903).

• The charging voltage may be a maximum of 14.4 V.

• If the battery must be replaced, follow the disposal regulations, refer to => [ Pollution risk. ] Lead-Acid Battery Warnings and Safety Precautions.