
The common charging methods of lead-acid battery are constant current charging, constant voltage charging, floating charging, overcharging and so on.
Charging is generally divided into two stages:
The first stage depends on the lead-acid battery capacity setting, the capacity of the larger charging current can choose a larger, for example, 60 ~ 100Ah battery can choose the charging current for the summer with 10A charging current; other seasons with 15A charging current, charging 6 ~ 10h or so. When the voltage of lead-acid battery rises to the maximum (i.e. 6V battery rises to 7.5V, 12V battery rises to 15V, 24V battery rises to 30V), the first stage of charging is finished.
In the second stage, the battery will be charged for 3~5h with 1/2 of the first stage charging current, so that the battery will rise to (6V to 7.8V, 12V to 15.5V and 24V to 30V). When the battery is fully charged, the battery voltage rises to the rated value, the electrolyte density no longer changes, and there are violent bubbles around the pole plate.
Attentions for battery charging are as follows:
a. Operate strictly according to the specification.
b. When the electrolyte temperature exceeds 40℃, the charging current should be reduced; when the temperature rises to 50℃, charging should be stopped and artificial cooling should be taken.
c. Always open the liquid filling cover when charging, and cover it again after a period of time after charging, so that the remaining gas can escape from the battery.
d. Each connector in the charging circuit should be connected firmly.
Correct Discharge.
When the battery is fully charged, it can be discharged. Correctly grasp the depth of discharge is the key to ensure good working condition and prolong the service life of the battery. Therefore, in the discharge process, the discharge voltage, current, electrolyte density, liquid temperature and other data should be checked regularly to analyze and determine the depth of discharge and charge at the right time.
The discharging capacity of the battery decreases sharply with the increase of discharging current. If the capacity of the battery is 100% at 10h discharge rate, the capacity of the battery is reduced to 75% at 3h discharge rate. Therefore, different discharge rates (discharge currents) are used for different batteries for different applications. When the overall battery voltage drops to 2.1V and the electrolyte density drops to 1.18g/cm, the discharge should be stopped to prevent the battery from being damaged by deep discharge.
Furthermore, the battery should be overcharged to restore it to normal use when the following conditions are found.
a. 24V battery is discharged to a voltage of 21V or less.
b. The battery is parked for 1~2 days and nights after the end of discharge without timely charging.
c. The electrolyte is mixed with impurities.
d. Sulfuration of the pole plate.
The method of overcharging is that after normal charging, continue charging with half of the current of 10h discharge rate, and observe the voltage and electrolyte density once an hour when the voltage and electrolyte density are at the maximum. If there is no change for 4 times in a row, and the bubbles around the pole plate are intense, you can stop overcharging. Under normal circumstances, the maintenance and preservation of lead-acid battery is much simpler than that of cadmium-nickel battery, and the service life of lead-acid battery is 8~10 years, if it is not properly maintained, its life will be greatly reduced. The normal parameters of lead-acid battery are: the density of electrolyte is 1.285g/cm ³ (20℃), and the voltage of single cell is 2.1V.
Use and maintenance of lead-acid battery charging and discharging should pay attention to the following matters.
①. The wiring should be correct and the connection should be secure. In order to prevent the wrench from latching and causing damage to the battery, the installation should be connected to the negative terminal first, then to the connection line between the two batteries, and finally to the latching line. When removing the battery, proceed in the opposite order.
②. Check the battery parameters once a week. The electrolyte level should always be 10~15mm higher than the pole plate, if the electrolyte level drops, add distilled water in time, do not expose the pole plate to the liquid level, otherwise it will damage the pole plate. When electrolyte is not enough, only distilled water can be added, river water, well water and tap water are strictly forbidden, otherwise the battery will be damaged due to excessive density of electrolyte.
③. Adjust the density of electrolyte in time according to the change of region and temperature. In high temperature areas, use less dense electrolyte; in cold areas, the electrolyte density should be larger to prevent icing.
④. Usually observe whether the battery shell is broken, whether the installation is secure and whether the wiring is tight. Remove the dirt and oil on the battery surface, wipe off the electrolyte on the battery cover, remove the oxidation layer on the pole pile and the wire connector, keep the battery surface clean and dry. If the surface of the battery is too dirty, it will cause slow discharge and damage the battery. The battery pole pile should be protected with petroleum jelly to prevent oxidation and rusting. The liquid filling hole cover should be tightened and the ventilation hole on the cover should be unblocked.
⑤. When the voltage of single battery is lower than 1.8V or the density of electrolyte is lower than 1.15g/cm³, don’t continue to use it, and should be charged in time. Each charge must be sufficient to prevent under-charging. The use should try to increase the charging opportunity, often keep the battery in the state of sufficient power to work. The fully discharged battery should be charged within 24h.