Car battery common faults and troubleshooting methods

The failure of the battery in use, in addition to materials and manufacturing processes, is in many cases caused by improper maintenance and use.

Internal faults of the battery include plate vulcanization, active material shedding, internal short circuit, and self-discharge.

First, the plate vulcanization

Definition: When the battery is not fully charged for a long time or is not charged for a long time after discharge, a layer of white coarse-grained lead sulfate will gradually form on the plate and cannot be converted into lead dioxide and spongy lead during normal charging. This phenomenon is called “ Lead sulfate hardening, referred to as "vulcanization".

Hazard: This coarse and hard lead sulfate crystal has poor conductivity and large volume, which will block the pores of the active substance, hinder the penetration and diffusion of the electrolyte, increase the internal resistance of the battery, and cannot supply a large starting current at the start. The engine cannot be started. There is a thick white frost on the surface of the vulcanized plate. There will be an abnormal phenomenon during charging and discharging. The battery capacity will decrease significantly during discharge. When the high rate discharge meter is used for inspection, the voltage of the cell will decrease sharply. The temperature of the electrolyte rises rapidly, but the density increases slowly, and the phenomenon of "boiling" occurs prematurely.

The main reasons for sparseness:

1) The battery is not fully charged for a long time, or it is not charged in time after discharge. When the temperature changes, the lead sulfate recrystallizes.

2) The liquid level in the battery is too low, so that the upper part of the electrode is in contact with the air and is strongly oxidized (mainly the negative plate).

3) The relative density of the electrolyte is too high, and the electrolyte will be impure and the external temperature will change drastically.

Countermeasures: In order to avoid the vulcanization of the plates, the battery should always be in a fully charged state. The discharged batteries should be charged in time, the relative density of the electrolyte should be appropriate, and the liquid level should meet the requirements. For the vulcanized battery, the lighter one can be treated by the overcharge method, and the more severe one can be eliminated by the small current charging method or the desulfurization charging method.

Second, self-discharge

Definition: A fully charged battery will gradually lose its charge when placed without being placed. This phenomenon is called “self-discharge” of the battery.

Type: normal self-discharge, faulty self-discharge

If the self-discharge amount exceeds 2% to 3% for one day and night, it is a faulty self-discharge, which is mainly caused by improper use and maintenance.

There are many reasons for causing faulty self-discharge, mainly in the following aspects:

1) The electrolyte contains too much impurity, and these impurities form a local battery around the plates to generate self-discharge.

2) Self-discharge caused by internal short circuit of the battery.

3) When the electrolyte is sprinkled on the battery cover, it will cause self-discharge, and at the same time, it will corrode the pole or connecting strip.

Countermeasures: The preparation of the electrolyte should meet the requirements, and the liquid level should not be too high. The surface of the battery should be kept clean during use. The battery with serious self-discharge can be completely discharged or over-discharged, so that the impurities on the plate enter the electrolyte, then the electrolyte is poured out, the battery is carefully cleaned with distilled water, and finally the new electrolyte is recharged.

Third, the plate short circuit

Fault phenomenon: the open circuit voltage is low, the terminal voltage drops rapidly when the large current is discharged, even to zero; during the charging process, the relative density of the voltage and the electrolyte rises slowly, even if the value is kept low, the bubble is very low at the end of charging. Less, but the electrolyte temperature rises rapidly.

Reason: The quality of the separator is not high or damaged, so that the positive and negative plates are in contact with each other and short-circuited; if the active material is deposited too much at the bottom of the battery and the metal conductive material falls between the positive and negative plates, the internal plate of the battery will be short-circuited.

Countermeasure: For short-circuited batteries, they must be disassembled and the cause should be removed.

Fourth, the plate active material drops off a lot

The active material shedding usually occurs on the positive electrode plate.

Characteristics: There is a precipitate in the electrolyte. When the electrolyte is charged, the brown substance rises from the bottom; the voltage rises fast, the boiling phenomenon of the electrolyte is earlier than that of the normal battery; the charging time is greatly shortened, and the discharge capacity is obviously decreased.

Reason: The quality of the plate itself is too poor. The volume of the active material is constantly expanding and contracting during charging and discharging. After sufficient electricity, a large amount of air bubbles escape from the pores of the plate, causing pressure inside the plate, so that the active material is easy to fall off. .

Note: Improper use (such as excessive charge and discharge currents, electrolyte temperature is too high, or often overcharged, etc.) will lead to premature damage to the plates. In addition, when the battery is subjected to severe vibration, it may cause the active material to fall off.

Fifth, the pole arch

Plate arching also occurs mostly in the positive plate.

Hazard: After the pole plate is bent, it will cause internal short circuit and other faults.

the reason:

1) During the manufacturing process, the lead paste is unevenly coated, so that the electrochemical reaction caused by the various parts of the plate during charging and discharging is not uniform, resulting in different expansion and contraction of the plates.

2) Frequently, a large current discharge causes the current density of each part of the surface of the plate to be different and causes bending.

3) When the battery is over-discharged, lead sulfate is formed deep in the inner layer of the electrode plate, and the inner plate is not restored when the charging is caused, and the plate is curved due to internal expansion.

4) The electrolyte contains impurities. When causing local electrochemical action, only a small part of the active material is converted into lead sulfate, which causes the volume change of the active material of the entire plate to be inconsistent.

Countermeasure: When the plate is slightly curved, it can be clamped and corrected by wood splint. If the plate is severely curved, the new plate should be replaced.