Page 211 - Mechanic Diesel - TT

MECHANIC DIESEL - CITS

7 Loss of Water.

8 Variation in Specific Gravity of Electrolyte.
Self-discharging
When a battery sits unused for a while, it loses its charge gradually. This is known as self-discharging. A new
battery typically loses about 1% of its charge each day when left unused. If a battery loses 3% or more of its
charge daily, it’s considered defective. Keeping the battery clean from dust particles and using pure sulfuric acid
and distilled water can help reduce self-discharging. If a battery remains idle for a long time, the electrolyte can
deteriorate, leading to a phenomenon called stratification, where it becomes heavier at the bottom. This can
cause localized current flow, accelerating self-discharging. To address self-discharge, the electrolyte should be
removed and the battery washed with plain water followed by distilled water. Then, it should be recharged with
fresh electrolyte.
Sulfation
Occurs when lead sulfate accumulates on the battery plates during discharge, and if a discharged battery remains
idle for an extended period, large crystals of lead sulfate form, which don’t convert back into lead peroxide during
recharge. This condition, called sulfation, increases the internal resistance of the cell and causes the plates
to become distorted. Sulfation is often caused by a low quantity of electrolyte and very high specific gravity.
Preventive measures should be taken to avoid sulfation, but if it occurs, sulfated batteries can be recharged using
slow charging rates.
Internal short circuit
An Internal Short Circuit Occurs When the Separator in The Battery Is Damaged, Or When the Active Substance
Falls from The Plates. This Leads to Rapid Self-Discharge and Sulfation. To Prevent This, It’s Important to Replace
the Damaged Separator and Ensure the Battery’s Interior Remains Clean.
The battery plates can sustain damage due to several factors:
1 Excessive charging rate

2 Elevated specific gravity of electrolyte
3 Incorrect electrolyte level
4 Normal wear and tear from maintenance activities.
If the container cracks due to a shock or fall, it must be replaced.
Rusting of battery terminals and clamps occurs due to oxidation, which disrupts the circuit. Regular cleaning is
necessary to prevent this
The Electrolyte in A Battery Consists of a Mixture of Sulfuric Acid and Water. Over Time, Water Evaporates from
The Electrolyte, Reducing Its Quantity. It’s Important to Periodically Check the Electrolyte Level and Add Distilled
Water as Needed to Maintain the Correct Quantity and Specific Gravity. Keeping The Specific Gravity Within the
Correct Range Ensures Optimal Battery Performance.
To Maintain Optimal Performance, The Specific Gravity of Each Cell in A Battery Should Remain Consistent.
However, Fluctuations in The Amount of Water or Acid Can Cause Changes in The Specific Gravity of the Cell.
Regular Monitoring and Adjustments Are Necessary to Ensure That the Specific Gravity Remains Within the
Desired Range for Each Cell.

Their remedies
• Maintain electrolyte levels by adding distilled water periodically.
• Ensure vent plugs are clean.
• Keep battery connectors and cells free from soil or debris by washing with hot water.
• Clean sulphade battery terminals with hot water and apply petroleum jelly; use trickle charge if the vehicle is
unused for some time.
• Secure the battery firmly inside its box to prevent cracking.

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CITS : Automotive - Mechanic Diesel - Lesson 57 - 61