Porsche 996 TT, Repair Manual

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If the hand−held multimeter shows a battery voltage below 12.5V: Charge battery.
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Battery load test
Note
The electrolyte gravity test provides information about the state of the battery in connection with the
battery load test. •
A battery test device is required for the load test. Gr. 3.9.1; Battery test charge device, Workshop
Equipment Manual. •
The battery must not be removed or disconnected. •
The battery must be charged before the load test is performed. •
Carry out battery load test:
1. Switch ignition off and remove ignition key.
2. Observe the information in the operating instructions of the battery test
device.
3. Connect the pliers of the test lines to the battery terminal as described in the operating instructions
of the test device.
As the load current varies, the current must be set depending on the battery capacity (operating
instructions of test device).
The load test currents can also be referred to in the following tables.
4. Carry out the battery load test according to the operating instructions and compare to the test result of the
following tables.
A minimum voltage is determined by the battery load test depending on the specified battery voltage.
Table:
Battery capacity: 80Ah
Cooling test current 380A
Load current 300A
Minimum voltage (limit value) 9.5V
5. If the minimum voltage is not attained, replace battery.
Remarks on battery load test:
The battery voltage sinks during this test due to the severe load on the battery.
•
If the battery is in order, the voltage value only reduces to the minimum voltage. •
If the battery is faulty, the battery voltage will sink very quickly below the specified minimum
voltage. •
After the test has taken place, the low voltage value remains over a long period of time, the voltage
increases again slowly. •
einordnung
Open−circuit voltage measurement 331