Updated: Mar 2
The life of the lead acid battery depends on the operating conditions and the effective maintenance practices followed for regular checking of battery health. The useful life of the lead acid battery can be achieved up to its guaranteed life if the charging and discharging cycles of the battery is as per ideal operating procedure.
The major reasons of battery failures or reduced battery life caused by loss of active material, insulation failure of separator and damage of the connection points of the battery due to rapid oxidation. The following reasons generally contributes to reduction of useful life of the battery.
The battery charging equation is as given below.
During charging process lead sulfate converts into the active material at anode and cathode. The oxygen(O2) gas is liberated at the anode and hydrogen(H2) gas is liberated at the cathode when battery is about to charge. If battery is charged above its capacity, the following pernicious effects will happen.
The gas formation during overcharging cause water to breakdown in hydrogen and oxygen gas. The gas formed interacts with the active material and this process scrub the active material. As a result, the battery charging and discharging capacity gets deteriorated for the next cycles.
The excessive charging reduce the water level of the battery. Rapidly lowering of water level in the battery is indication of battery overcharging.
The overcharging of battery cause excessive heat inside the battery. The excessive heat can cause buckling and wrapping which may eventually cause damage to the separators.
If the battery is not fully charged, it can not deliver the rated amperage to the load, the sulphation formation on the plates is likely to occur because specific gravity of the battery is low.. The discharge equation of the lead acid battery is as given below.
A battery can not deliver the rated amperage to load if battery is undercharged.
Local Galvanic Action
If the local galvanic action is formed in the entire battery, more charging current is required to boost the battery voltage. The excessive charging will reduce the useful life of the battery. If the local galvanic action is formed in a particular cell of the battery, overcharging of the battery will not boost the battery voltage. The only solution in this case is charging such battery separately.
Loss of Active Material
The loss of the active material can be seen as a sediment in the bottom of the battery. If the active material loss occurs, the battery will draw more current for charging and ampere hour capacity of the battery gets lowered. After substantial loss of active material from the plates of the battery, the battery life gets lowered and the battery must be replaced.
Excessive Rate of Charge or Discharge
The battery must be charged and discharged according to the design rating of the battery. Excessive charging and discharging cause heat inside the battery which may damage the plates and separator.
The electrolytic action takes place when the electrolyte comes in the contact with the grid of positive plate. This can cause the cracks in the grid frames and further it may break the plate apart.
Entrance of Impurities
The water added to battery to maintain the specific gravity of the cell must be free from the impurities. The impurity in the distilled water may cause local galvanic action.
Low Water Level
The water level in the battery must be maintained up to the marked level on the battery. The more acid concentration may damage the separators of battery cells and it can permanently damage the battery. The local galvanic action aggravate with low water level in the battery and finally it will reduce the battery voltage.