The charging time of lead-acid batteries is closely related to their service life, and the specific relationships are as follows:
When the charging time is too short:
Resulting in undercharging of the battery: If the charging time is insufficient, the battery cannot reach a fully charged state. Over time, this will cause the active substances inside the battery to sulfide. A layer of white lead sulfate crystals will gradually form on the battery plates. Such crystals are very difficult to be completely converted into active substances during subsequent charging processes, thereby reducing the battery capacity and lifespan. For example, if the battery is supposed to be charged for 8 hours but is only charged for 3 to 4 hours each time, and the battery remains in an undercharged state for a long time, its capacity will gradually decrease. A battery that could originally be used for 3 years may become unusable within 1 to 2 years.
Shortening the cycle life: Undercharging will make the battery unable to discharge all its power during the next discharge. With such incomplete charge-discharge cycles over a long period, the cycle life of the battery will be shortened, that is, the number of times the battery can be fully charged and discharged will be reduced.
When the charging time is too long:
Accelerating the aging of the plates: During overcharging, the electrolysis reaction of water will occur inside the battery, generating a large amount of hydrogen and oxygen. Oxygen will enter the battery separator, causing the positive active substances to be impacted by the gas, resulting in the shedding of the active substances. At the same time, the grid alloy of the plates will also suffer severe anodic oxidation and corrosion, damaging the structure and performance of the plates, and thus affecting the battery capacity and service life.
Causing water loss in the battery: Excessive charging time will cause the water in the electrolyte to decompose into hydrogen and oxygen and be discharged, leading to the evaporation and dryness of the water in the electrolyte. This will make the concentration of sulfuric acid too high, further accelerating the aging of the plates. It may also increase the internal resistance of the battery, affecting its charging and discharging performance and shortening the battery life.
Triggering thermal runaway: Long-term charging will cause the battery to generate excessive heat. If the heat dissipation is not timely, the battery temperature will keep rising, which will lead to the phenomenon of thermal runaway. This will break the chemical equilibrium inside the battery, accelerate the aging and damage of the battery, and may even trigger safety accidents.
Therefore, grasping the appropriate charging time is very important for extending the service life of lead-acid batteries. Generally speaking, when the battery is completely discharged (100% power consumption), the charging time is usually between 8 and 10 hours, but it is not recommended to exceed 12 hours. When the battery has about 70% of its power remaining, the charging time is approximately 6 to 8 hours. After the charger indicator turns green, a floating charge can be continued for an additional 0.5 to 1 hour to ensure that the battery is charged to the best state.
