Lead-acid batteries are composed of positive and negative plates, separators, shells, electrolyte and terminal posts, etc. The chemical reaction of its discharge depends on the active materials of the positive plate (lead dioxide and lead) and the active materials of the negative plate. (Sponge pure lead) is carried out under the action of electrolyte (dilute sulfuric acid solution). The grid of the electrode plate is made of lead-antimony alloy in traditional batteries, and the maintenance-free battery is made of lead-calcium alloy. The former is made of antimony and the latter is made of lead-calcium alloy. With calcium, this is the fundamental difference between the two. Different materials will produce different phenomena: traditional batteries will lose liquid during use. This is because the antimony on the grid will contaminate the spongy pure lead on the negative plate, which reduces the reaction in the battery after being fully charged. The electromotive force causes excessive decomposition of water, and a large amount of oxygen and hydrogen escape from the positive and negative plates respectively, reducing the electrolyte. Substituting calcium for antimony can change the back electromotive force of the fully charged battery, reduce the overcharge current, and reduce the liquid vaporization speed, thereby reducing the loss of electrolyte.

Because the maintenance-free lead-acid battery uses a lead-calcium alloy grid, the amount of water that is generated during charging is small, and the amount of water evaporation is low. In addition, the shell is sealed, and the release of sulfuric acid gas is also very small, so it is comparable to traditional batteries. Compared with, it has the advantages of no need to add any liquid, less corrosion to the terminal posts and wires, strong resistance to overcharge, large starting current, and long power storage time. Maintenance-free lead-acid battery because its electrolyte only produces a small amount of gas under normal charging voltage, the plate has strong resistance to overcharging, and has small internal resistance, good low-temperature starting performance, and longer service life than conventional batteries. Features, so there is no need to add distilled water during the entire period of use, and under normal conditions of the charging system, there is no need to remove it for supplementary charging. However, the specific gravity of the electrolyte should be checked during maintenance.

Most maintenance-free lead-acid batteries are equipped with a hole-shaped liquid (temperature-compensated) hydrometer on the cover, which changes color according to changes in the specific gravity of the electrolyte. It can indicate the storage state of the battery and the height of the electrolyte level. When the indicator eye of the hydrometer is green, it indicates that the battery is fully charged and the battery is normal; when the indicator eye has few green dots or is black, it indicates that the battery needs to be charged; when the indicator eye is light yellow, it indicates that the battery is faulty and needs repair or Replace it.

Maintenance-free lead-acid batteries can also be recharged, and the charging method is basically the same as that of ordinary batteries. When charging, the voltage of each cell should be limited to 2.3-2.4V. Note that charging with conventional charging methods will consume more water, and the charging current should be slightly smaller (below 5A) during charging. Fast charging is not allowed, otherwise, the battery may explode and cause injury. When the hydrometer of a maintenance-free battery is displayed in amber or red, it means that the battery is close to being scrapped, and its service life will not be long even if it is recharged. Charging at this time can only be used as an emergency measure.

When conditions permit, maintenance-free lead-acid batteries can be charged with charging equipment with current-voltage characteristics. The device can ensure sufficient power and avoid excessive water consumption due to overcharging.