The reason and treatment methods of internal short circuit in lead-acid battery
1. The short circuit phenomenon of lead-acid batteries is mainly manifested in the following aspects:
1) The open circuit voltage is low, and the closed circuit voltage (discharge) quickly reaches the termination voltage.
2) When a large current is discharged, the terminal voltage drops rapidly to zero.
3) When the circuit is open, the density of the electrolyte is very low, and the electrolyte will freeze in a low temperature environment.
4) When charging, the voltage rises very slowly and always keeps a low value (sometimes drops to zero).
5) When charging, the electrolyte temperature rises very quickly.
6) When charging, the electrolyte density rises slowly or hardly changes.
7) When charging, there is no bubble or gas appears very late.
2. The main reasons for the internal short circuit of the lead-acid battery include:
1) The quality of the separator is poor or defective, so that the active material of the plate passes through, resulting in virtual or direct contact between the positive and negative plates.
2) The displacement of the separator causes the positive and negative plates to be connected.
3) The active material on the pole plate swells and falls off. Due to the excessive deposition of the shed active material, the lower edge or side edge of the positive and negative plates contacts with the deposits, resulting in the connection of the positive and negative plates.
4) Conductive objects fall into the battery to connect the positive and negative plates.
5) The "lead flow" formed when welding the electrode group is not completely removed, or "lead beans" exist between the positive and negative plates during assembly, and the separator is damaged during charging and discharging, causing the positive and negative plates to be connected.
3. Treatment method for short circuit of lead-acid battery:
The following mainly analyzes the short circuit of the lead-acid battery caused by excessive charging current, charging voltage of a single battery exceeding 2.4V, internal short circuit or partial discharge, excessive temperature rise, and valve control failure, and summarizes the following lead-acid battery short circuit The processing method:
1) Reduce the charging current, lower the charging voltage, and check whether the safety valve body is blocked. Charge and discharge regularly. The floating charge voltage and discharge voltage of the lead-acid battery in the UPS power supply system have been adjusted to the rated value at the factory, and the discharge current increases with the increase of the load. The load should be adjusted reasonably during use, such as Control the number of electronic devices such as computers used.
In general, the load should not exceed 60% of the rated load of the UPS. In this range, the battery will not be over-discharged. The storage of lead-acid batteries will lose part of their capacity due to self-discharge. Therefore, before the lead-acid batteries are put into use after installation, the remaining capacity of the batteries should be judged according to the open circuit voltage of the batteries, and then different methods should be used to supplement the batteries. For the spare storage battery, a supplementary charge should be carried out every 3 months. The quality of the battery can be judged by measuring the open circuit voltage of the Panasonic battery.
2) Taking a 12V battery as an example, if the open circuit voltage is higher than 12.5V, it means that the battery energy storage is still more than 80%. If the open circuit voltage is lower than 12.5V, it should be supplemented immediately. If the open circuit voltage is lower than 12V, it means that the battery stores less than 20% of the electric energy and the battery is unusable. When the battery is in a short-circuit state, its short-circuit current can reach hundreds of amperes. The firmer the short-circuit contact, the greater the short-circuit current, so all the connecting parts will generate a lot of heat, and the heat will be greater in the weak link, which will fuse the connection and cause a short circuit.
Part of the battery may produce explosive gas (or accumulated explosive gas during charging), and sparks will be generated when the connection is blown, which will cause the battery to explode; if the short-circuit time of the battery is short or the current is not particularly large, the connection may not be caused Fuse at the place, but the short circuit will still cause overheating, which will damage the adhesive around the connecting strip, leaving hidden dangers such as leakage.
Therefore, in the process of using lead-acid batteries, we must pay attention to the correct use of batteries, and there must be no short circuit. When installing a lead-acid battery, the tools that should be used should take insulation measures. When connecting the wires, first connect the electrical appliances other than the battery. After checking that there is no short circuit, finally connect the battery. Prevent overlapping pressure from cracking. Through these meticulous work, the short circuit of the lead-acid battery can be better prevented, the use of the lead-acid battery will be safer, and the service life will be longer.
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