Basics / Battery / Maintenance of Lead Acid Battery

Maintenance of Lead Acid Battery

Avoid Overcharging

We should avoid overcharging of the lead-acid battery. Because of overcharging, may make the lead sulfate harden. Hence, it becomes difficult to convert it to the active materials. Hence, the specific gravity of the electrolyte permanently becomes low. Consequently, it hampers the rate of electrolysis.

Identifying Sulfate Condition

Although, we can easily find the sulfated condition plates. Because, in that case, the color of plates becomes lighter. Also, the surface of the plates becomes unpleasantly rough and grainy. Such defected cell evolves gas even during normal charging. Therefore, the capacity of the cell decreases. If we keep the sulphation unattended for a long time, the damage becomes permanent. Hence, it will be next to impossible to rectify the cell. So this is always safe to charge a lead acid battery for a long time with a low charging current.

Maintaining External Connectors

The terminal connectors of the battery are prone to corrosion. The corrosion causes loose connections. So we have to check the tightness of the connectors regularly.  Also, we need to cover the connectors with a layer of petroleum jelly.

Conditioning Old and Unused Cells

When the cell becomes quite old, the specific gravity of the electrolyte decreases below its normal value. There may be a tendency of sedimentation at the bottom of the old cell. This is due to the prolonged effect of the gravitational force. Also, for gas bubbling during charging, some amount of electrolyte may spray out to the upper wall and top cover of the cell container. Then it is dried there and permanently lost. In addition to these, excessive sulphation in the cell also causes loss of sulfuric acid. Because the sulfuric acid is the source of sulfur for sulfation. To restore the specific gravity we can add concentrated sulfuric acid to the cell.

Conditioning Defective Cells

Sometimes short circuit may occur between the positive and negative plates. Excessive gas bubbles passing through the passage between the plates make loose the active materials on the plates. The particles of active materials may accumulate between the positive and negative plates. These loosen active materials may create a bridge between the plates. We can remove these loosen active materials with the help of ebonite stick. Also, a short circuit may occur due to buckling or bending of plates. We can rectify this defect by inserting additional separators in the passage between the plates. Also, we can rectify the defect, by removing and straightening the plates mechanically.

After rectification of the short circuit, we have to restore the specific gravity of the electrolyte by proper charging.

Maintaining Battery Lead Acid Battery Room

During overcharging there may be gassing in the battery room. These may pollute the space in the room. Hence, a spacious room and with adequate ventilation is essential for the installation lead acid battery. The oxygen and hydrogen are the main gasses evolve from the cells. These gases can explode and create fire hazards in contact with flamed or flameless fire. Hence we should not bring any fire in the battery room. Also, we must not smoke in this room.

battery room

Also, we must arrange at least one exhaust fan of suitable capacity, in this room. This keeps the interior of the room free from those gases. We must maintain the temperature of the room above 10°C.

We must paint the walls, ceilings, doors, windows, ventilators, metal parts and other apparatus in the room with anti-acidic color.

Also to avoid any fire hazard from an electrical short circuit, we use conduit electrical wiring. Moreover, we need to use flameproof lighting fittings. Also to avoid any fire hazard from arcing and electric sparking, we must install all the switches, fuses and plug sockets outside the room. We should clean the floor and walls on a regular basis.

Some Do’s and Do not’s for Lead Acid Battery Maintenance

Idle Lead Acid Cell

We do not keep a flooded-type lead acid battery idle for a long time. Due to the gravitational force, the uniformity of the electrolyte may be disturbed. The concentration of sulfuric acid will become higher in the lower portion of the cell container than that in the upper portion. The upper portion of the cell may become pure water only. So during service, the current distribution in the electrolyte will not be uniform. As a result, charging and discharging action on the entire plate surface will not be uniform. Therefore, the cell may have permanent defects.

Avoid Quick Charging

Also, we do not charge the battery with a very high rate. In that case, the temperature of the electrolyte rises beyond a limit. Also, this causes excessive gassing. Consequently, the excessive bubbling at high temperature causes the spilling of electrolyte from the cells. Considering this we must control the charging process. So that the temperature must not rise more than 40°C.

Recharging after Deep Discharge

Also after a deep discharge, we allow the battery to be completely charged before it put into the service. Otherwise, the sulfate layers on the electrode plates cannot be removed completely. Hence, this causes permanent sulfation on the plate. Therefore the lifespan and the performance of the battery deteriorate.

Checking During Charging

During charging, we should measure the voltage of each of the battery cells.  Then we should check whether the voltage of each cell is equal or not. Also, we have to compare the readings with the previous record (if any).

Maintaining the Level of Electrolyte

Sometimes, the level of the electrolyte comes below its recommended level. This is due to the natural and higher temperature evaporation of water. Although the main cause of loss of water is overcharging of the battery. During overcharging, the water molecules split into hydrogen and oxygen. Thereafter the gases evolved from the container. Therefore, the water loses its molecules. So we should regularly check the level of the electrolyte in the cell. If we find it is low, we have to top up the distilled water through water filling hole on the top of the cell container.  Again, we have to be careful about the filling level. Because overfilling may cause an overflow of electrolyte during gas bubbling in the electrolyte.

Conditioning Specific Gravity

We should measure the specific gravity of electrolyte at least after two weeks from topping up. It is to ensure thorough mixing of water in the electrolyte. Obviously, during the measurement, we have to correct the value of specific gravity with temperature.

We should run a discharging and then overcharging cycle once in 2 to 3 months interval. During the process, we must follow the instruction given by the manufacturers.

Maintaining Hydrometer

We must always keep the hydrometer for measuring specific gravity in a clean place. Also, we should clean and wash the hydrometer with distilled water after every cycle of measurement. Otherwise, it may affect the reading of specific gravity.

Pilot Cell

For regular monitoring the condition of the battery, we have to arbitrarily choose a cell in the battery bank. Then we perform the cell voltage and specific gravity measurement at this cell on a daily basis. We call this cell as the pilot cell. Also, we should not change the pilot cell for a month, once it is chosen. But we must change the pilot cell at the beginning of every monthly interval.

Recommendation of Replacement of Electrolyte

The manufacturers also recommend replacing the electrolyte once in three years. Because it improves the health and performance of the battery.


In addition to these above-mentioned recommendations, also we have to follow the instruction manual of the battery for the purpose.

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