13.11.
Battery Faults, Care and Maintenance
13.11.1.
Faults
Any electrical device including battery can suffer from either open circuit or a short circuit faults. In addition battery can also have other problems such as low charge or low capacity. Often a problem apparently with a vehicle battery, can be traced to another part such as the charging system. All the common problems faced by lead-acid batteries, together with typical causes are listed in Table 13.7.
Table 13.7. Common Problems with Lead-acid Batteries. |
|
| Low state of charge. | Charging system fault. Unwanted drain on battery. Electrolyte diluted. Incorrect battery for application. |
| Low capacity. | Low state of charge. Corroded terminals. Impurities in the electrolyte. Sulphated. Old age-active material fallen from the plates. |
| Excessive gassing and temperature. | Overcharging. |
| Short circuit cell. | Damaged plates and insulators. Build up of active material in sediment trap. |
| Open circuit cell. | Broken connecting strap. Excessive sulphation. Very low electrolyte level. |
| Service life shorter than expected. | Excessive temperature. Battery has too low a capacity. Vibration excessive. Contaminated electrolyte. Long periods of not being used. Overcharging. |
Many of the problems listed in Table 13.7 can not be attended and hence require the replacement of the battery. With sulphation it is some times possible to bring the battery back to operation with a long low current charge. A fortieth of the ampere hour capacity or about two hundredths of the cold start performance, for about 50 hours is considered as appropriate rate.
13.11.2.
Care and Maintenance
Topping Up. Once every month for normal batteries or annually for maintenance-free batteries, the level of the electrolyte in the cells must be checked to ensure that the plates are adequately covered. The correct level generally is just above the top edges of the separators, which stands about 6 mm above the plates. Only distilled water or de-ionized water must be added to maintain the electrolyte level if falls due to evaporation of water.
Battery Cleaning. The battery should be kept clean and dry, and water spillage should be wiped away. Any acid spillage on metal should be removed with baking soda and hot water, to minimise corrosion. After neutralising corroded metalwork, these areas should be repainted with acid resisting paint.
Battery-terminal Corrosion. Corroded battery posts and terminals should be covered for a short period with a rag soaked in hot water, which rapidly removes the products of corrosion. After cleaning them, they must be smeared with petroleum jelly or, at least grease. This provides protection to certain extent against further corrosion. Battery terminal should be kept clean for better electrical continuity.
Mixing Electrolyte. In order to prepare acid and water mixture, the acid should be added slowly to the water while stirring with a wood or glass rod. Water should never be added to the acid, as the water being lighter does not mix with the acid but floats on top of it. The chemical reaction between the acid and water then generates heat so that the water boils, and steam and acid spray in the form of small explosions, which may cause an accident.
Battery-terminal Disconnection. One or both cable terminals should be removed from the battery when any large component is being dismantled or removed from the vehicle or when electrical components such as the starter and generator are being removed. This eliminates the occurrence of a short circuit caused by a cable rubbing against a metal surface or by one of the cables becoming entangled and pinched between components.
Personal Safety Precautions. One should not smoke or allow a spark or naked flame to come close to the battery during its removal or installation, as the oxygen and hydrogen gases generated by charging can easily catch fire and explode. When acid is splashed on to any part of the body, the area affected should be immediately treated with sodium-bicarbonate solution or, if this is not available, clean water.
