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Common faults of batteries include internal faults and external faults.


Time:

2021-06-07

The external faults mainly include shell cracks, pole corrosion, pole looseness, and dry cracking of the sealant; while internal faults mainly include pole plate vulcanization, active material shedding, pole plate grid corrosion, pole plate short circuit, self-discharge, and pole plate arching.

The external faults mainly include shell cracks, pole corrosion, pole looseness, and dry cracking of the sealant; while internal faults mainly include pole plate vulcanization, active material shedding, pole plate grid corrosion, pole plate short circuit, self-discharge, and pole plate arching.

One, plate vulcanization

The phenomenon that a layer of white coarse-grained PbSO4 formed on the battery plate cannot be converted into PbO2 and Pb during normal charging is called "lead sulfate hardening", that is, "vulcanization". This kind of coarse-grained lead sulfate has poor conductivity and is difficult to restore under normal charging. The coarse grains and large volume block the pores of active materials, hinder the penetration of electrolyte, and increase the internal resistance of the battery.

1, failure phenomenon

① The battery capacity drops rapidly during discharging, and the single cell voltage drops rapidly when tested with a high-rate discharge meter;

② The density of the electrolyte drops below the specified normal value;

③ The voltage of the battery is too high at the beginning of charging and when the charging is completed, which can reach more than 2.7V;

④ When the battery is charging, the electrolyte temperature rises too fast, easily exceeding 45 ℃; at the same time, bubbles are generated prematurely, even at the beginning of charging;

⑤ Hard, insoluble large white particles are formed on the plate.

2, the cause of the failure

① The battery is under-charged for a long time or is not charged in time after discharge, causing a part of the lead sulfate on the electrode plate to dissolve in the electrolyte. The higher the ambient temperature, the greater the solubility. When the ambient temperature decreases, the solubility decreases, and the dissolved lead sulfate will re-precipitate and crystallize again on the plate.

② The accumulator is often over-discharged or low-current deep-discharge, resulting in the formation of lead sulfate in the inner layer of the small pores of the electrode plate, and it is not easy to recover from charging.

③ If the electrolyte level is too low, the active material on the upper part of the electrode plate is exposed to the air to be oxidized. The fluctuation of the electrolyte when the car is running makes it contact with the oxidized active material, producing coarse-grained lead sulfate.

④ If the initial charge is not complete or regular supplementary charge is not performed, so that it can be used for a long time in a semi-charged state, the discharge product lead sulfate on the electrode plate will exist for a long time, and it will also form coarse particles through recrystallization.

⑤ If the electrolyte density is too high or impure, the battery will discharge by itself, and lead sulfate will be produced, which will provide the material basis for the recrystallization of lead sulfate.

3. Measures

① Slightly vulcanized, can be charged with a low current of 2-3A for a long time, that is, overcharge; or use full discharge and full charge to reduce the active material; it can also be eliminated by desulfurization charging

②When the vulcanization is serious, it should be scrapped and replaced;

③ Keep the battery always in a fully charged state:

A, the battery on the car is regularly sent to the charging room to be fully charged;

B. The discharged battery shall be charged in the charging room within 24h.

④The height of the electrolyte should meet the regulations.

2. Self-discharge

The phenomenon that the battery automatically disappears when there is no load is called self-discharge.

1, fault characteristics

Ordinary batteries will have a certain degree of self-discharge due to their own structure. However, if the capacity self-discharge per day and night does not exceed 2% C20, it belongs to normal self-discharge; if the self-discharge volume per day and night exceeds 2% C20, it belongs to faulty self-discharge.

2, the cause of the failure

① The electrolyte is impure, and the impurities in the electrolyte settle on the electrode plate to produce partial discharge.

② The electrolyte overflowed from the battery accumulates on the cover, making the positive and negative poles form a loop, and at the same time, it will corrode the poles.

③ If the battery is left unused for a long time, the sulfuric acid sinks, the lower part has a higher density than the upper part, and the potential difference between the lower part of the electrode plate causes self-discharge and so on.

④ The internal short-circuit of the battery causes self-discharge. For example, the separator ruptures or the active material of the electrode plate falls off and deposits on the lower part of the electrode plate to short-circuit the positive and negative plates, causing self-discharge.

3. Measures

In order to reduce the self-discharge of the battery, it can be prevented from the following aspects:

(1) Use standard sulfuric acid and distilled water to prepare electrolyte;

(2) Keep the electrolyte container clean;

(3) Prevent impurities from entering the battery;

(4) The surface of the battery should be kept clean and dry. Self-discharge treatment measures: for lightly self-discharged batteries, you can pour out the electrolyte after the battery is discharged normally, rinse it with distilled water repeatedly, and then add new electrolyte to fully charge it;

When the self-discharge is serious, fully discharge the battery, pour out the electrolyte, take out the plate assembly, take out the separator, rinse with distilled water, reassemble, and add new electrolyte.

3. The active substance falls off

1, fault characteristics

The shedding of active material on the electrode plate mainly refers to the shedding of PbO2 on the positive plate. It is characterized by that brown material can be seen from the filling hole during charging, the electrolyte is turbid, the voltage of the single cell rises quickly, and the electrolyte "boils" prematurely. Phenomenon: When discharging, the battery capacity drops significantly.

2, the cause of the failure

(1) The charging current is too large and the electrolyte temperature is too high, which makes the active material swell, soft and easy to fall off;

(2) The overcharge time is too long, electrolyzed water → produce H2↑ and O2↑→ impact the active material on the electrode plate;

(3) Frequent low-temperature high-current discharge causes the plate to bend, causing the active material to fall off;

(4) Bumps and vibrations when the car is driving;

3, troubleshooting methods

For the lead-acid battery with active material falling off, if there is less sediment, it can be removed and used again; if there is more sediment, new plates and electrolyte should be replaced.

Fourth, the pole plate is short-circuited

1, fault characteristics

The positive and negative plates of the battery are in direct contact or overlapped by other conductive materials, which is called a plate short circuit.

The charging voltage of the battery with short-circuited plates is very low or zero when charging, the electrolyte temperature rises rapidly, the density rises very slowly, and there are few bubbles at the end of charging; when discharging, the battery capacity drops significantly.

2, the cause of the failure

(1) The separator is damaged so that the positive and negative plates are in direct contact;

(2) A large amount of active material falls off, and the positive and negative plates are connected after deposition;

(3) The plate group is bent;

(4) Conductive objects such as metal impurities fall between the positive and negative plates;

3, troubleshooting methods

When the plate is short-circuited, the battery must be disassembled and inspected; the broken separator should be replaced, the deposited active material should be eliminated, and the bent plate group should be corrected or replaced.

Five, other failures

(1), plate grid frame corrosion

1, fault characteristics

The main reason is the corrosion of the positive grid frame, the electrode plates are in a rotten state, and the active material is accumulated in the form of blocks between the separators, and the output capacity of the battery is reduced.

2, the cause of the failure

(1) The battery is often charged, and the O2 produced at the positive plate oxidizes the grid;

(2) The electrolyte density and temperature are too high, and the charging time is too long, which will accelerate the corrosion of the electrode plate;

(3) The electrolyte is impure;

3, troubleshooting methods

(1) For batteries with lighter corrosion, if there are impurities in the electrolyte, pour out the electrolyte and wash it with distilled water repeatedly, then add new electrolyte, and it can be used after charging;

(2) For batteries with severe corrosion, if the electrolyte density is too high, you can adjust it to the specified value and continue to use it without charging;

(3) For batteries with severe corrosion, such as grid fracture, active material falling off in pieces, etc., the plates need to be replaced;

(two), the battery capacity does not meet the specified requirements

1. Failure phenomenon

① When the car starts, the speed of the starter slows down quickly, and the rotation is weak

② The sound of honking the horn is weak and weak;

③ Turn on the headlights, the lights are dim;

2, the cause of the failure

① The initial charge is not performed as required before using a new battery.

② The voltage of the generator regulator is adjusted too low, so that the battery is often under-charged.

③ Start the starter often for a long time, causing large current discharge and damage to the pole plate.

④ The relative density of the electrolyte is lower than the specified value, or after the electrolyte leaks, only distilled water is added, and the electrolyte is not replenished in time, resulting in a decrease in the relative density of the electrolyte.

⑤ The relative density of the electrolyte is too high or the electrolyte level is too low, causing the vulcanization of the electrode plate.

3, troubleshooting methods

① First check the exterior of the battery to see if the outer shell is in good condition, if there are cracks, if the surface is clean, and if there is corrosion and dirt on the electrode plate. If there is, it is an external self-discharge fault of the battery, which shall be eliminated according to the corresponding fault.

②Check the battery ground connection, whether the connection clip of the pole is loose, and whether the connection between the battery wiring pole and the plate is broken. If there is, the output resistance is too large and the voltage is reduced.

③Measure the electrolyte density of the battery. If the electrolyte density is low, it means that the charge is insufficient or the new battery does not go through the charge and discharge cycle as required, so that the battery does not reach the specified capacity.

④Check the height of the electro-liquid level. If the electro-liquid level is not high enough and there are white crystalline substances on the plate, there may be a plate vulcanization failure.

⑤Check the electrolyte density after charging the battery. If there is a significant difference in the electrolyte density between two adjacent batteries, for example, in 6 single cells, the electrolyte density of 5 batteries is 1.16g/cm, and the other The density of the battery is 1.08g/cm, which means that the single cell battery has a short circuit inside and cannot be used.

⑥ If necessary, check the regulated voltage of the generator voltage regulator.

(three), the polarity of the single cell battery is reversed

1. Failure phenomenon

The original positive plate of the single cell battery becomes the negative plate, and the negative plate becomes the positive plate. At this time, the voltage of the battery drops rapidly and cannot be used continuously.

2, the cause of the failure

When the faulty single cell battery is not found in time (such as short-circuit of the plate, active material falling off, etc.), when the battery is discharged, the single cell battery is first discharged to zero due to its small capacity, and then continues to discharge, the discharge current of the other single cell batteries Charge it so that its polarity is reversed;

3, troubleshooting methods

For single cells with reversed polarity, replace with new plates