How to charge lead-acid battery _ lead-acid battery charging principle

A lead-acid battery (VRLA) is a battery whose electrode is mainly made of lead and its oxide, and the electrolyte is a sulfuric acid solution. When the lead-acid battery is discharged, the main component of the positive electrode is lead dioxide, and the main component of the negative electrode is lead. In the state of charge, the main components of the positive and negative electrodes are lead sulfate. A single-lead lead-acid battery has a nominal voltage of 2.0V, can be discharged to 1.5V, and can be charged to 2.4V. In applications, 6 single-cell lead-acid batteries are often used in series to form a 12V lead-acid battery. There are also 24V, 36V, 48V and so on.

The anode (PbO2) and the cathode (Pb) in the lead Storage Battery are immersed in the electrolyte (dilute sulfuric acid), and 2V of electricity is generated between the two poles. According to the principle of the lead storage battery, the anode and the cathode and the electrolyte will be charged and discharged. The following changes have occurred:

(anode) (electrolyte) (cathode)

PbO2 + 2H2SO4 + Pb ---》 PbSO4 + 2H2O + PbSO4 (discharge reaction)

(lead peroxide) (sulfuric acid) (sponge lead)

The valence of Pb in PbO2 is reduced, reduced, and negatively charged; the valence of Pb in spongy lead increases, and positive charge flows.

(anode) (electrolyte) (cathode)

PbSO4 + 2H2O + PbSO4 ---》 PbO2 + 2H2SO4 + Pb (Charging reaction) (must be energized)

(lead sulfate) (water) (lead sulfate)

The valence of lead in the first lead sulfate is increased, oxidized, and a positive charge flows into the positive electrode; the valence of lead in the second lead sulfate is lowered, reduced, and a negative charge flows into the negative electrode.

When the battery is connected to an external circuit, the dilute sulfuric acid reacts with the active material on the anode and anode plates to form a new compound, "lead sulfate." It is released from the electrolyte via the discharge sulfuric acid component, and the longer the discharge, the thinner the sulfuric acid concentration. The consumed component is proportional to the amount of discharge. As long as the concentration of sulfuric acid in the electrolyte is measured, that is, the specific gravity is measured, the amount of discharge or the amount of residual electricity can be known.

Since the lead sulfate produced on the anode plate during charging is decomposed and reduced to sulfuric acid, lead and lead peroxide during charging, the concentration of the electrolyte in the battery gradually increases, that is, the specific gravity of the electrolyte rises, and Gradually returning to the concentration before discharge, this change shows that the active material in the battery has been reduced to a state where it can be re-powered. When the lead sulfate of the two poles is reduced to the original active material, it is equal to the end of charging, and the cathode plate is Hydrogen is produced, and the anode plate generates oxygen. When charging to the final stage, the current is almost used in the electrolysis of water, so the electrolyte is reduced. In this case, it should be supplemented with pure water.

The discharged battery must be charged before it can be put back into service;

The new battery and the repaired battery must be initially charged before first use;

In order to maintain a certain capacity and prolong the service life of the battery during normal use, it is necessary to carry out some necessary supplementary charging operations such as supplementary charging and balanced charging.

Therefore, the charging operation is an important part to ensure the good performance of the battery during the whole use process and prolong its service life.

According to the purpose of charging, the charging operation of the battery can be divided into initial charging, supplementary charging, desulfurization charging and the like.

The first charge of a new or repaired battery before use is called initial charging;

Purpose: To restore the amount of electricity lost by the partial active material on the plate during slow storage and self-discharge during storage.

Whether the initial charging is appropriate or not is extremely important for the performance of the battery.

The characteristics of initial charging: small charging current, long charging time, and sufficient electrochemical reaction.

When the battery is used on a vehicle, there is often a phenomenon of insufficient charging, especially for short-distance transportation vehicles, which should be recharged as needed.

Generally, once a month, if there are the following phenomena, you must recharge at any time:

1) The relative density of the electrolyte drops below 1.15;

2) The discharge in winter exceeds 25%, and the discharge in summer exceeds 50%;

3) The lighting is dim and the starter is running weak, indicating that the power is insufficient.

In addition, when the battery is left for more than one month, it should also be recharged; it should be recharged after a large amount of distilled water is added.

The battery is often partially discharged during use. The active substances participating in the chemical reaction are limited. In order to force the active material equivalent to the rated capacity to work, to avoid the active material shrinking for a long time without working, it can be performed every 3 months. Cycle exercise charging.

That is, after the battery is fully charged, the battery is discharged at a discharge rate of 20h, and then sent out after normal charging.

When the plate is vulcanized more seriously, "desulfurization charging" can be performed.

During the use of the battery, due to manufacturing, use and other factors, there will be differences in the terminal voltage, electrolyte density, capacity, etc. of each single cell. The method of equalization charging can eliminate this difference.