Battery Fault Diagnosis

Battery Over Discharging or Deep Cycling

Every time a battery is charge and discharge cycled a small amount of material is lost. If a battery is subjected to overdischarging or deep cycling (greater than 35%) and rapid charging the process is accelerated. Additionally if the recharge does not recover the discharge cycle in full, the battery will exhibit loss of performance and concentration of the acid can occur between plates which can lead to corrosion and loss of performance. Even after recharging, the voltage will be low (under 12.4V) but if the cells acid gravities are checked they will generally be even across the battery. This is not a manufacturing fault.



1.  Open circuit voltage is below 10V (12V batteries. Half for 6V batteries)

2.  Proportion of electrolyte is below 1.15.

3.  Surface of positive plate is yellow or yellow-white (chocolate brown commonly); pole plate is bent so severely (that batteries have short circuit or broken plate-grid).

4.  Active materials of positive and negative plate are too hard to be broken easily.

5.  Users say batteries do not store electricity.


Possible Reason or Cause

1.  Continue to use batteries in undercharge.

2.  Car power line short-circuits.

3.  Electric part of vehicles is not turned off after usage.

4.  Voltage of car body charging regulator is too low (13.8 below)

5.  Placed away for a long time without timely charge.

6.  Users add electric liquid of above-norm impurity into batteries, or put drinking mineral water or water from pond, river, well, brook, field or lap into batteries while usage, which cause severe self-discharge.

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