Battery: Description and Operation

The sealed battery is standard on all cars There are no vent plugs in the cover. The battery is completely sealed, except for two small vent holes in the sides. These vent holes allow the small amount of gas produced in the battery to escape. The battery has the following advantages over conventional batteries:
- No water addition for the life of the battery.
- Overcharge protection. If too much voltage is applied to the battery, it will not accept it. In a conventional battery, the excess voltage will still try to charge the battery, leading to gassing, which causes liquid loss.
- Not as liable to self-discharge as compared to a conventional battery. This is particularly important when a battery is left standing for long periods of time.
- More power available in a lighter and smaller case.
The battery has three major functions in the electrical system. First, the battery provides a source of energy for cranking the engine. Second, the battery acts as a voltage stabilizer for the electrical system. Finally, the battery can, for a limited time, provide energy when the electrical demand exceeds the output of the generator.