Repair methods and preventive measures for vulcanization of lead-acid battery plates
2022 Jul 23 By admin 0 comment

The repair of the vulcanization failure of the battery plate is to find a way to soften, refine and dissolve the white and hard dendritic sulfate crystals on the plate, enhance the original reversible chemical reaction ability of the active material of the plate, and restore it to a good state. performance.

The sulfate crystals generated by the vulcanization of the plates are generally difficult to be electrolytically reduced to lead if charged with conventional chargers. For plate vulcanization failure, the following methods are usually used for flexible repair. (For more battery repair knowledge visit Tycorun Battery)

  1. Several repair methods for mild or moderate vulcanization of polar plates

1) Repeated charge and discharge repair method
First fully charge the battery with the standard charging current, and then discharge the 6V battery to 5.4V with the current of C10, and discharge the 12V battery to 10.8V. The mild sulfate on the plate is gradually electrolyzed into lead dioxide, velvet lead and sulfuric acid, which can eliminate the phenomenon of plate vulcanization and restore the capacity of the battery.

2) Intermittent charging repair method
First fully charge with constant current or constant voltage, and then stop for 1h. Then charge with a small current of C20 for 2h, and stop for 1h. Then charge with C130 current for 2h and stop for 1h. After repeating this for 4-5 times, until the charging power is turned on, the single-cell voltage of the battery can reach 2.4V, and the single-cell voltage at the end of the charging period can be stabilized at 2.5V, and the electrolyte density does not increase within 2h. , it shows that the plate has recovered its original performance.

3) Spa charging repair method
After discharging the battery, pour out the electrolyte, pour it into distilled water to fully shake and clean it, and then pour it out. After cleaning for 3 times, add distilled water to submerge the plate. Then charge with C/20 current for more than 24 hours, the slight sulfate on the plate will gradually decompose, and sulfuric acid will be precipitated, the positive plate will be reduced to lead dioxide, the negative plate will be reduced to velvety lead, and the precipitated sulfuric acid will penetrate into distilled water. , the density (concentration) of the sulfuric acid solution increases. After continuous charging until the density of the solution no longer increases, stop charging, then discharge and pour out the electrolyte, inject distilled water again, and repeat continuous charging with the current of C20. When the density of the electrolyte or the voltage of the battery no longer increases, it means that No more sulfuric acid is decomposed on the plate, and the sulfide that marks the plate has been eliminated. At this time, the electrolyte should still be poured out. Finally, the electrolyte of standard density is injected, and it can be used according to conventional charging.

It should also be noted that this repair method is particularly effective for the repair of light and moderate vulcanization of open large battery plates, and the operation effect is better at around 40 °C. The biggest feature of this maintenance method is that it does not require professional equipment. But the process is cumbersome and requires patience.

4) Two-speed current charging repair method
Pour out all the electrolyte in the battery, replace it with distilled water, and charge it with a small current of C25. When there are many bubbles in the electrolyte and the temperature does not exceed 45 °C, reduce the charging current to C/50 and continue charging until the voltage is equal to When the density of the electrolyte no longer increases and remains stable for 3h-4h, it means that the mild vulcanization of the electrode plate has been eliminated. At this time, it can be quickly discharged and the electrolyte and precipitated impurities can be poured out, replaced with electrolyte of standard density, and then charged and discharged 2-3 times with standard current. This not only eliminates the plate vulcanization, but also restores the capacity of the battery.

5) Low-density charging repair method
Pour out the electrolyte in the battery, inject the electrolyte with a density of 1.04g/cm³-1.06g/cm³, and charge it with a C20 current for more than 20 hours, until the density of the electrolyte no longer rises, and the sulfides on the plates are eliminated. Then replace the electrolyte with standard density for standard charging and it can be used.

6) High current cycle charging repair method
Use a current of about C/5 for constant current charging. Under the condition that the electrolyte does not exceed 45 °C, the battery is charged to a slightly overcharged state, and then 30% of the power is discharged. Repeat this 2-3 times to eliminate the phenomenon of plate vulcanization. This method has obvious effect on repairing the slight vulcanization of the pole plate. However, it is not suitable for serious vulcanization repair of the electrode plate, because the gas precipitated by high current charging will strongly wash the sulfate crystals and active substances on the electrode plate at the same time, so that the active substances fall off with the crystals, causing damage to the electrode plate.

7) Pulse repair method
The method is to use a special pulse repairing instrument to repair, the pulse repairing instrument can output pulse voltage, replace the DC voltage to charge the battery, and the pulse repairing instrument can also be automatically charged in the form of continuous charging (long time) and discharging (short time). Charging the battery in a converted way can effectively eliminate the vulcanization phenomenon of the pole plate, which is the most efficient and easiest way to repair the pole plate vulcanization. For general plate vulcanization, the narrow pulse charging with a frequency of 8330Hz is the best, and the steeper the rising edge of the pulse, the more harmonics, and the better the effect of eliminating plate vulcanization.

After using the above methods to repair mild and moderate plate vulcanization faults, the capacity of the battery should also be tested. If it can reach more than 80% of the rated capacity, it means that the repair is successful. If it cannot be achieved, it should be repaired by the following heavy vulcanization repair method.

Lead-acid battery plate vulcanization
Lead-acid battery plate vulcanization
  1. Several repair methods for severely vulcanized plates

When the battery plate is severely vulcanized, the white sulfate crystals have been covered with the plate, and the following methods can be used to repair it.

1) Small density and low current composite repair method
Inject distilled water into the battery to reduce the density of the electrolyte to below 1.0g/cm³, and charge it with the current of C20. When the single cell voltage rises to 2.4V, stop for 30 minutes. Then reduce the charging current to C140, and continue to charge until the voltage, electrolysis The liquid density was stable, and then stopped for 30 minutes. After that, it is still charged with C20, and the cycle is repeated 3 times and 4 times until the battery reaches the normal state. Finally, pour out the electrolyte and rinse it with distilled water, replace it with the standard electrolyte and charge it with a standard current, and it can be used normally.

2) Small current charge and discharge repair method
Inject distilled water into the battery to immerse the electrode plate and charge it with the current of C720. When the density of the electrolyte rises to 1.10gcm~1.12g/cm², reduce the current to C/50 and continue charging. Stop charging when the density of the electrolyte no longer rises and bubbles emerge from the plates. Then discharge with C/50 current for 2h. After that, repeat the above process cycle 3-5 times until the electrode plate returns to the normal state. Finally, the standard electrolyte with a density of 1.26g/cm³ is replaced and fully charged, and it can be put into use. This repair method takes a long time, sometimes weeks.

3) Potassium solution chemical repair method
Pour out the electrolyte of the battery and wash it thoroughly with distilled water. Then prepare a mixed chemical electrolytic repair solution by adding 0.1%-0.5% potassium carbonate to the sulfuric acid electrolyte with a density of 1.1g/cm³-1.1sg/cm³. Inject the mixed solution into the battery and charge it with C20 current for a long time. When the voltage of a single cell reaches 2.4V, reduce the current to C/40 and continue to charge until the battery voltage no longer rises, and then use the standard current for one-time discharge. Such repeated charging and discharging 2-3 times, when the battery capacity recovers to 80% of the rated capacity, it means that the severely vulcanized sulfate on the plate has been dissolved. After that, rinse the inside of the battery twice with distilled water, and then add standard sulfuric acid electrolyte before regular charging.

  1. Several repair methods for stubborn vulcanization of plates

For batteries with stubbornly vulcanized plates, the electrolyte is almost dry, and the crystals on the plates are mostly white powder. In this case, the following methods can be used to repair.

1) Sodium solution chemical repair method
Pour out the electrolyte of the battery, inject 10% sodium sulfate solution, and charge it with a small current below C20 for 70h-80h. Then pour out the sodium solution, rinse it with distilled water, and inject sulfuric acid electrolyte with a density of 1.26g/cm³. Finally, charge and discharge once with standard current. If the battery capacity can be restored to about 90% of the rated capacity, it means the repair is successful.

2) Chemical mixture repair method
First add 4% magnesium sulfate, 17%-25% aluminum sulfate, 3%-7% zinc sulfate, 10%-18% tartaric acid and 1%-3% disodium EDTA into distilled water Salt (disodium EDTA), prepare a mixed chemical electrolytic repair solution. Then pour out the remaining electrolyte in the battery, inject the repair solution, and let it stand for 12h. After that, charge it with 6A current for Sh-30h, and then discharge it with 5A current for 25h. The stubbornly sulfided lead sulfate dissolves. Then pour out all the repair fluid in the battery and rinse it twice with distilled water. Finally, a standard sulfuric acid electrolyte with a density of 1.26g/cm³ was injected for conventional charging.

If the test battery capacity can reach 80% of the rated capacity, it means the repair is successful, otherwise only the plates can be replaced or scrapped. Practice has proved that this method has the following characteristics: 0. It improves the chemical reaction speed of lead sulfate, and can restore the stubbornly vulcanized positive and negative plates to loose lead dioxide and velvety lead; ability and self-resurrection ability, which can prolong the service life of the battery; ③ reduce the internal resistance of the battery, improve the effective capacity, and restore the performance of the failed battery: @ In general, this method has a high repair efficiency and a multi-functional Success: ⑤ The disadvantage of this method is that it is cumbersome to operate, which will cause the battery to have a certain self-discharge side effect.

3) Disassembly and desalination repair method
Pour off the electrolyte and rinse with distilled water. Disassemble the battery, remove the sulfide on the plate with a wire brush or hacksaw blade, clean the battery case, replace with a new separator, then reassemble the battery, and then follow the “sodium solution chemical repair method” It can repair the stubborn vulcanization of the plate and restore the capacity of the battery.

  1. Measures to prevent lead-acid battery plate vulcanization

The solution to the vulcanization failure of the battery plate focuses on the prevention in daily use. Here are several methods to avoid the vulcanization of the battery plate.
(1) The battery cannot be fully discharged at ordinary times, and the “discharge termination voltage value” should be retained, that is, a certain minimum power can be saved.
(2) Batteries that are temporarily idle should be charged once a week for maintenance.
(3) The liquid level should be checked every 15 days in winter and every 7 days in summer. Distilled water should be added when insufficient to avoid vulcanization of the electrode plate exposed to the liquid surface. However, sulfuric acid electrolyte must not be added to prevent the electrode plate from being vulcanized due to the excessive concentration of the electrolyte.
(4) The power of the battery should be checked regularly. Especially for batteries used in tractors and automobiles, the density of the electrolyte should be detected every 500h of operation to determine the self-discharge situation.
The density of the electrolyte should be adjusted to 1.3g/cm³ in winter and 1.27g/cm³ in summer, which is also one of the preventive methods to avoid vulcanization of the plates.
(5) Always keep the surface of the battery clean to prevent the deep vulcanization of the plates caused by low current discharge. Do not put metal tools on the battery cover to prevent short-circuit high-current discharge or over-discharge, and avoid vulcanization of the plates.
(6) Do not discharge excessively high current, especially for the battery used for starting. Each start should not exceed 5s. When starting continuously, the interval should be 15s-20s each time. If it still cannot be started for 4 consecutive times, the battery should be stopped to prevent the plates from vulcanizing.

Read more: Explain in detail the detection methods and specific applications of lead-acid batteries