Defects and Remedies In Cells
Defects in secondary cells, Symptom, causes and cure
| Nature of defects | Symptoms | Causes | Cure |
| 1.Backward or weak cells | 1.Lowering of Sp.gr and voltage
2. Failure to gas along with other cells of the same battery. |
1. Internal short cct. Between plates of opp. Polarity
2. Sulphation |
1.Remove short cct. Download
2. Curative charging with alternate charge and rest periods. 3. Bridging backward cell during a few discharges. 4. Use of milking booster |
| 2.Buckling of plates | 1. Can be readily noticed | 1. Uneven working with plates not being in parallel.
2.Abnormal sulphation. 3. Over charging. 4. Impurities like iron in electrolyte |
1. Fully charged plates to be removed and straightened by a hand press or wooden mallet. This procedure is not to be attempted in case of brittle plates. |
| 3.Abnormal sulphation of plates | 1 Colour of the plates becomes lighter in shade. Download
2. Loss of capacity. 3. Lower Sp.gr. and voltage. 4. Negatives become hard expanded and gritty. 5. Positives felt hard and |
1. Improper operating procedure such as over discharging, under-charging, rapid rate of discharge, failure to top up.
2. Neglect of internal short cct. 3. Impurities in electrodes. 4. Excessive temperature |
1. Prolonged charge at low rate between half and quarter, or normal rate, with alternate rest, and charge periods.
2. To remove very hard sulphation, empty the acid and fill up with water and give prolonged charge at low rate. |
| 4.Abnormal sedimentation | 1. Noticed on inspection | 1. Overcharging at low rate
2. Excessively High rate of charge. 3. Running down cells too much on discharge. |
1. Leveling the heaps of sediment with wooded rod.
2. Cleaning out. 3. Flushing out. 4. Restoring charge after cleaning and flushing.
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Nature of defects |
Symptoms |
Causes |
Cure |
| 5.Reversal of cell or battery | 1. Measurement of voltage during discharge will indicate this defect.
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1. Wrong connections.
2. Failure to detect a weak cell and to take action to bring it up. |
1. Pasted plates are likely to lose all their active material and hence very little possibility of recovery.
2. Pasted plates if they do not break up can be recovered by a few cycles of charge and discharge in the proper direction. |
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6. Internal discharge or local action |
1.Gassing on open cct. and on discharge. 2. increase in loss of capacity in open cct. By more than 1.2% per day. |
1. Impurities in the plates or electrolyte. |
1. Renewal of electrolyte may help in some cases. |
| 7. Positive plates disintegrating corroding or breaking up
|
1. Detected by visual inspection.
2. Loss of capacity. |
1. Impurities such as iron and chlorine in electrolyte.
2. Dress in material of the plates. |
1. Renewal of electrolyte may help.
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| 8. Growth of positive plates. | 1. Detected by inspection | 1. Organic acids in the electrolyte.
2. Normal growth due to development of new material in pasted plates. |
1. Action to be taken to prevent secondary actions such as buckling and internal short ccts. |
| 9.Negative plate blowing | 1. Puffing out or fudging of active material beyond grid. | 1. Excessive of expander in active elements.
2. Charging at high rate |
1. Prevent secondary action such as short ccts |
| 10. Shrinkage of negative plates | 1. Detected by visual inspection.
2. Loss of capacity |
1. Expander driven out due rate of charging. | 1. Can’t be recovered under service conditions. |
Defects and Remedies In Cells
| Nature of defect |
Symptom |
Cause |
Cure |
| 11. “Treeing” on negative plates | 1. Soft tree like growths on the edges of the negative plates. | 1. Overcharging.
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1. Removed by introducing a scaling stick.
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| 12. Premature gassing of bty or cell | 1. Gassing sets in even before full charge is put in and before the Sp.gr. increases.
|
1. Low capacity of negative plate.
2. Sulphation of negative plate.
|
1. Prolonged charging at such low rate that the plate do not gas. |
| 13. Bad colour of plates | 1. Visual inspection, healthy positive should have deep chocolate colour and healthy negative deep gray with metallic luster. | 1. Impurities in electrolyte & sulphation.
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1. Try to remove causes of sulphation.
|
| 14. Hydration of the plates
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1. White creamy substance spread irregularly over plates.
|
1. Action of water on plates.
2. Discharging cells to too low a Sp.Gr. |
.The plates get sulphated. Action to be taken for sulphated plates. |
| 15. Discoloration of the electrolyte |
1. Electrolyte should be colorless. |
1. Overcharging causes expander being forced out causes black colour. 3. Presence of manganese in parts its colour to electrolyte |
1. Electrolyte to be changed |
| 16.Lowering of Sp.gr. of electrolyte | 1.Can be detected by measurement of Sp.gravity | 1.Loss of acid due to spilling or spraying.
2.Stratification. 3.Ageing |
1.Loss of acid may be made good.
2.Stirring electrolyte by allowing cell to gas. |
| 17.Separator failure | 1.Internal short circuit.
2.Can be detected by visual inspection also |
1.Buckling of plates
2.Chemical action at higher temperature 3.Presence of Manganese and Cobalt in electrolyte |
1.Replace worn out separator |
Remedies In Cells
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