Battery Fault Diagnosis

Battery Overcharging

If the alternator regulator is not set properly, or alternator voltage control circuit fails, then the battery can be subjected to an excessive charge. If left unchecked the battery will overheat and will start to evaporate the electrolyte. The overcharging will accelerate the break up of the active material and grids and the battery will lose performance. Examination of the battery will typically show low acid level and usually a black coating on filler plugs and a strong smell. It is recommended that the alternator charging voltage is checked by a mechanic. This is not a manufacturing fault.



1.  Battery case turns dark.

2.  Clapboard becomes black.

3.  Electrolyte turns red or level of electrolyte goes down.

4.  Active materials of pole plate fall off severely.

5.  Capacity table points to red area.

6.  It is difficult to start vehicles, hot batteries.

7.  Proportion of electrolyte is higher than standard value.

8.  Positive plate-grid of batteries is rotten and broken.



1.  Voltage regulator for vehicles has a high set point (charging voltage of 12V auto batteries is 13.8-14.4V)

2.  Charging voltage regulator of vehicles is out of control.

3.  Charge in heavy current for a long time deliberately. (charging voltage of 12V motorcycle batteries is 14-14.5V, half for 6V batteries)

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