1. High current charging

The method of charging with large current to dissolve large lead sulfate crystals was adopted. It was found in the experiment that this method can only obtain temporary effect to eliminate sulfurization, and will cause water loss and positive plate softening during the elimination of sulfurization, causing serious damage to battery life. Now few people use this simple method to repair batteries.

2. Full charge and full discharge repair method (deep discharge repair)

The full charge and full discharge repair method is to fully charge and then discharge the battery. The full charge and full discharge repair method is important for the repair of slightly damaged batteries. At the same time, this method can also effectively activate the active substances in the deep layer of the battery and improve the capacity of the battery. It is applicable to slightly sulfurized batteries and batteries with high internal resistance. The key of this method is that the discharge must be sufficient, and each battery must be fully discharged separately. The capacity of the battery can be generally improved after full charge and discharge for 1~2 times. The full charge and full release repair method cannot be used frequently, and it can be used once every three months at most.

3. Shallow circulating high current charging method

For the sulfurized battery, use high current (current within 5h rate), charge the battery to a slightly overcharged state, control the electrolyte temperature not to exceed 40 ℃, and then discharge 30%. Repeat this several times to reduce and eliminate sulfurization.

The mechanism of this method is that the surface of the electrode plate is slightly washed by the gas released from overcharge, so that it can be desorbed and dissolved and transformed into active substances.

This method is characterized by obvious repair with respect to slight vulcanization. However, it is not suitable for old batteries, because the released gas washes the sulfate and also strongly washes the active substance of the positive plate, making the active substance soft or even fall off.

4. Add active agent

For the sulfurized battery, add pure water mixed with sodium sulfate, potassium sulfate, tartaric acid and other substances, take normal charging and discharging several times, then pour out pure water and add slightly high-density acid solution to adjust the concentration of acid solution in the battery to the standard solution, and it can be considered that the repair is successful when the capacity recovers to more than 80%.

The mechanism of this method is that these sulfate coordination dopants can form coordination compounds with many metal ions, including sulfate. The formed compound is unstable in acidic medium, and the non-conductive sulfide layer will gradually dissolve and return to the solution.

Chemical method is used to eliminate lead sulfate crystal, which not only has high cost and new battery internal resistance, but also changes the original structure of electrolyte. After repair, the service life is short, and the side use is large, and the repair rate is about 40%.

5. Impulse repair

For sulfurized battery, some special pulse repair instruments can be used to charge and discharge the battery several times to eliminate sulfurization. One is high voltage and high current pulse charging, which eliminates vulcanization through negative resistance breakdown. This method is fast and effective, but it has a great impact on the battery life. The other method is to use small current frequency as high as 8kHz and large crystal resonance to dissolve. This method is relatively slow to repair and has good repair effect. However, the repair time is relatively long, usually more than 120 hours.

In terms of solid physics, any insulating layer can be broken down under high enough voltage. Once the insulating layer is broken down, it will change from the insulating state to the conductive state. If a transient high voltage is applied to the sulfate layer with high conductivity and resistance, the large lead sulfate crystal can be broken down. If the high voltage is short enough and the current is limited, under the condition of piercing the vulcanized layer, the charging current should be properly controlled to prevent the battery from gassing. The amount of gas evolution of the battery depends on the terminal voltage and charging current of the battery. If the pulse width is short enough and the duty cycle is large enough, the simultaneous micro charging can not form gas evolution in time under the condition of ensuring the breakdown of coarse lead sulfate crystals. The addition of negative pulse during the charging process is useful for reducing the temperature rise of the battery, and it can also ensure that the gas evolution of the electrode plate is reduced when the sulfate layer is broken down, In this way, pulse elimination vulcanization is realized.