A dead battery is a familiar problem to most motorists. The way out is to charge the battery. Organizing the process correctly will help extend battery life and ensure 100% charge.
Car batteries are charged using one of two types of chargers, which can provide constant current or constant voltage during the process. Both methods are equivalent in terms of impact on battery life. Before charging a low battery, it is necessary to remove from it both terminals (plus and minus) connected to the vehicle's on-board system.
Constant current charging
To "calculate" the required charging current to restore the battery, you need to divide the capacity of your battery, expressed in ampere-hours, by 10. For example, if the battery is 60 A / h, then the charging current on the device must be set equal to 6 A. The main disadvantage such devices - the need for hourly monitoring of the current strength and a fairly strong release of gases near the end of the recovery process.
To reduce gassing, it is recommended to use a step reduction in amperage. When the voltage reaches 14.4 V, you need to reduce the current to 3 amperes (when charging a battery with a capacity of 60 A / h). If you have to charge the battery of the latest releases (they do not have holes for filling with distilled water), then it is advisable to make another decrease in the value of the charging current to 1.5 A (when the voltage rises to 15 V). The battery can be considered fully recovered if the voltage remains unchanged for at least an hour (16, 3-16, 4 V).
Charging with constant voltage supply
A heavily discharged battery has little resistance, so at the moment of connecting to the charger, the current can fly up to 40 A. To prevent this from happening and the device does not fail, the maximum current is limited to 20-25 A. The state of charge of the battery and the duration of the recovery process are related voltage supplied to the battery:
- 14.4 V: charge the battery by 70-80%;
- 15 V: 80-90%;
- 16.4 V: 100%, subject to the charging time (at least 20 hours, but not more than 24 hours).
During charging, the voltage at the terminals approaches the value given out by the charger, respectively, the current value drops and at the end of the process reaches zero. At this point, we can assume that the battery is fully charged. Usually, the end of charging is indicated by a green indicator available in some devices. It should be borne in mind that currently sold devices most often have a maximum output voltage of 14.4 V. Therefore, to be sure that the battery is fully restored, you need to leave it to charge for a day.
