How do you repair lithium battery?

Generally 18650 lithium batteries are increased in parallel by parallel. For example, the 20000mah mobile power supply is generally composed of 8 2600mah batteries or 6 3400mah 18650 batteries. Parallel adds 3.7V capacity. Then increase the voltage by series, 2 series is 3.7 * 2 = 7.4V, three 12.6V analogy.

Usually, electric vehicles and laptop batteries need to increase the battery voltage to 12V or 36V48v72V through multiple batteries in series. At this time, if the capacity or quality of the battery is not equal, there is always a loss in the use process. Like the short board principle of a wooden barrel, a battery or a group of batteries connected in parallel affects the total battery voltage and capacity of the entire battery pack.

The impact is that, for example, notebooks are generally 2 and 3 strings, which constitute a battery from 10.8V to 12.6V. A group of two parallel batteries will be depleted first, which will cause the whole battery to have a reduced capacity. Specifically, the battery has a short standby time, a fast charging speed, and fast power consumption. The same is true for electric vehicles and other equipment.

At this time, it is necessary to replace the battery pack and avoid the barrel effect (short board principle - the barrel can hold water depending on the shortest board of the barrel). This will allow the battery to be used evenly and extended.

Directly measure with a voltmeter, when the voltage across the 18650 battery is lower than 2.7V or no voltage, indicates that the battery or battery pack is damaged. The normal voltage is 3.0V~4.2V (the general 3.0V battery will be cut off, the 4.2V battery voltage will be fully charged, and the individual types will also be 4.35V)

The battery voltage is lower than 2.7V. You can charge the battery with the charger (4.2V). After 10 minutes, if the battery voltage rises, you can continue charging until the charger is full then look at the full voltage.

If the full voltage is 4.2V, the battery is normal. It should be that the last time the power consumption was too much and the battery was cut off.

If the full voltage is much lower than 4.2V, it means the battery is damaged. If it is a battery that has been used for a long time, it can be judged that the battery life is up and the capacity is basically exhausted. It should be replaced. Basically there is no way to fix it. After all, lithium batteries have a long life, not unlimited.

If the battery is measured, there is no voltage in the battery. There are two situations at this time. One is that the battery is good, and the battery is stored for a long time. This battery has a certain chance to recover. Generally, the battery is activated by a lithium battery pulse activation device, time to charge multiple times. It is possible to fix it. Generally, the cost of repair is not low, better buy a new one.

Another possibility is that the battery is completely worn out, the battery diaphragm breaks down, and the positive and negative poles are short-circuited. There is no way to fix this kind of thing, can only buy new ones.

As mentioned earlier, lithium battery packs should often be unusable because one or a group of batteries is damaged. At this time, the voltage across each battery should be measured one by one, and the voltage or voltage should be severely low (the previous one is described). Come out and replace the new battery of the same kind with similar internal resistance.

After the general replacement, the lithium battery pack can still be used up to the other battery life loss. This partial replacement is generally less expensive. It is also a commonly used method on the market.

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Lithium battery must be equipped with a protective plate to limit overcharge, over discharge, short circuit, etc., which is beneficial to extend the life of the lithium battery pack.

The current application of lithium batteries has become very popular. How can we save costs and rejuvenate the "dead" lithium batteries? Let me exchange experiences with you.

The suspended death of lithium batteries is generally divided into three cases.

First, the battery is not charged at all, the charger and the appliance are not recognized, and the electrode has no voltage.

Second. Can be charged, chargers, electrical appliances can also be identified, but only for a few minutes, the power is quickly exhausted.

Third, it can be charged, and the capacity is still sufficient, but the large current discharge voltage drops significantly (for example, the camera shooting mode can only last for a few minutes, and the look back mode can last for a long time)

This kind of "dead" battery, with the original charger is not charged (no current through), but with a DC power equal to the battery design voltage to charge the battery will find a relatively large current, and this charging current It will slowly decrease, approaching 0 after a few minutes. This is good news: the battery voltage is returning to the design level.

At this time, stop charging, and then use a multi-meter to measure the two poles of the battery. Is there a normal voltage?

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Then you can charge it with your original charger.

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In this way, I have fixed a lot of batteries, and many of them can recover to about half of the design capacity.

In order to completely activate the battery, it needs to be fully charged and discharged several times. The discharge circuit is composed of a resistor and a light emitting diode, and the state of the discharge can be estimated by the light emitting diode.

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In my experience, this method is very effective for the first battery. In the latter two cases, the battery is difficult to repair, and the information found on the Internet has little obvious effect. In particular, the third type "can be charged, and the capacity is sufficient, but the large current discharge voltage drops significantly (for example, the camera shooting mode can only last for a few minutes, and the look back mode can last for a long time)" A kind of battery, it is a pity to discard it.

Battery repair is a general term for repairing a secondary battery that has degraded or failed performance by physical or chemical means. By repairing, the battery capacity can be restored, the battery life can be extended, and the performance of the battery can be improved.

A battery, also known as a chemical power source, is a device that can provide a DC power source for an electrical appliance. The chemical power source converts chemical energy into electrical energy through an electrochemical reaction of redox. The primary battery is a one-time application battery, and the secondary battery is a battery that can be used repeatedly, so the second time here actually means multiple times. Secondary batteries are also known as rechargeable batteries or batteries.

Battery repair refers to the collective repair of batteries that have degraded or failed performance by physical or chemical means.

A secondary battery, also referred to as a "rechargeable battery", refers to a battery that can be activated by activation of the active material after the battery is discharged. The main rechargeable batteries on the market are "nickel hydride", "nickel cadmium", "lead acid (lead battery)", "lithium ion (including lithium battery and lithium ion polymer battery)" and the like. There are many methods for repairing lead-acid batteries, such as “water therapy”, “shallow cycle high-current charging method”, “nano-carbon sol battery activator repair”, “pulse battery repair instrument repair”, “battery repair fluid repair” and so on.

Sulfation

Irreversible sulfation, referred to as sulphation. When the lead-acid battery is discharged, the positive and negative plates produce a combination of lead sulfate. Lead sulfate is a poorly soluble, non-conductive substance under normal conditions. The lead crystal formed by the battery after discharge is relatively small. When charged, it is easily dissolved and reduced to lead under the action of electricity. If used improperly, it is often insufficiently charged, dehydrated, over-discharged, etc. When coarse and hard crystals are formed, it is difficult to reduce them to lead by a general method, so it is called irreversible sulfation. Due to sulfation, on the one hand, it can block the contact of sulfuric acid with other active substances. Reacts: On the other hand, the amount of active material is reduced, which can cause the battery capacity to drop, and in severe cases, the battery life will be terminated.

Exfoliation of actives

When we repair used batteries, some batteries are filled with water and some reddish brown liquid flows out from the water injection hole. It is the active substance that falls off. The reasons for the falling off of the active substance are as follows: 1. the battery is affected by external force, such as vibration, beats and so on. 2, α-PbO2.βPbO2 variant model. αPbO2 is the active material skeleton, when the battery is charged and discharged, a part of α-PbO2 is converted into β-PbO2, resulting in softening and shedding. 3, with the cycle, activity the material is gradually crystallized from the amorphous state, that is, the crystallinity increases, the number of hydrated polymer chains decreases, the gel pressure resistance increases, the electrical contact between the grains deteriorates, and the active material falls off. 4. It is also believed that with charging And the discharge continues, the active material forms a number of dense agglomerates. When there is insufficient connection between the agglomerates, the active material will fall off and the battery will fail.

Battery voltage

The potential difference between the positive and negative poles of the battery is called the voltage of the battery. It is generally measured with a multi-meter. During the battery repair process, the voltage has three manifestations: the first type is the no-load voltage, also known as the open circuit voltage, that is, the battery is not charged. Battery voltage measured without load: The second type is the load voltage, which is the battery voltage measured during a certain period of battery discharge. The third type is the line voltage, which is measured at a certain time during the charging process. The voltage, understand three voltage measurement methods, to determine whether the battery is open or short circuit; battery internal resistance calculation has important significance.

Battery capacity

The capacity of the battery is an important indicator to measure the performance of the battery. It is generally expressed in ampere-hour. The general term for discharge time (hours) and discharge current (amperes), capacity = discharge time × discharge current. The actual capacity of the battery depends on the amount of active material in the battery and the utilization rate of the active material. The more the active substance is, the higher the utilization rate of the active material, and the larger the capacity of the battery, the smaller the capacity.

The page contains the contents of the machine translation.