First, the battery is the source of energy needed to start the engine.
Secondly, to stabilize the voltage in the vehicle's electrical network.
Thirdly, to temporarily provide energy to connected consumers when the generator capacity is insufficient.
A sealed battery is standard on all cars. There are no vent plugs in the cover. The battery is completely sealed, except for two vent holes on the sides. These are used to release the small amount of gas that forms in the battery.
Sealed battery has the following advantages over standard batteries.
No need to add water during the entire service life of the battery.
A sealed battery is protected from overcharging. If too much voltage is applied to such a battery, it will not accept all the current, unlike a standard battery. In standard batteries, recharging continues at excess voltage, which leads to gas emission ("boiling" of the battery during charging) and, therefore, to loss of liquid.
This battery is not as susceptible to self-discharge as a standard one. This is especially important when the battery is left running for a long time.
With a lighter and smaller body, this battery has a greater power reserve compared to the standard one.
Nominal capacity
The battery has two nominal capacities:
- (1) Reserve power at 27°C, when a fully charged battery delivers 25A of current at 10.5V or higher;
- (2) the current strength when starting a cold engine, the value of which was determined at -18°C.
Reserve power
Reserve power is the maximum amount of time that the vehicle can be driven overnight with a minimum electrical load and the alternator not running. Expressed in minutes, reserve power is the time that a fully charged battery can maintain a terminal voltage of 10.5 volts at 27°C, with the battery being discharged at 25 amps.
Cold engine starting current
The cold start current reading is determined at a battery temperature of -18°C. This value is the minimum current that the battery must support for 30 seconds at the specified temperature, maintaining a minimum voltage of 7.2 V. This value is the cold start current.
A battery cannot remain in good condition indefinitely. However, with good maintenance, a battery can serve you well for many years.
If the battery works fine during testing, but then for no apparent reason fails to work during operation, the following factors may be the cause.
Auxiliary devices are left switched on in the car overnight.
Frequent and short trips were made over a long period, and the generator did not have time to fully restore the battery energy spent on starting the engine and powering consumers during the trip.
The electrical load is greater than the generator output, especially when additional equipment is installed after purchasing the machine.
There are faults in the charging system: for example, short circuits, a slipping alternator belt, a faulty alternator or a faulty voltage regulator.
Improper use of the battery: the battery cable terminals are not clamped or cleaned, or the battery is not pressed tightly to the shelf.
Mechanical causes: such as shorted or pinched electrical system wires.