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Lithium batteries refer to batteries containing lithium (including lithium metal, lithium alloys, lithium ions, and lithium polymers) in the electrochemical system. Lithium batteries can be roughly divided into two categories: lithium metal batteries and lithium ion batteries.
Lithium metal batteries are generally non-rechargeable and contain lithium in a metallic state. Lithium-ion batteries do not contain lithium in a metallic state and can be charged, so how to make lithium battery repair?
1. The charging and discharging principle of lithium-ion batteries
The working principle of lithium-ion batteries refers to their charge and discharge principle. When the battery is charged, lithium ions are generated on the cathode of the battery, and the generated lithium ions are moved to the anode by the electrolyte.
Since the carbon anode is a layered structure, it has many micropores, lithium ions reaching the anode are embedded in the micropores of the carbon layer, the more lithium ions are embedded, the higher the charging capacity. In the same way, when the battery is discharged (that is, the process by which battery is used), lithium ions embedded in the anode carbon layer come out and move back to the cathode.
The more lithium ions that return to the cathode, the higher the discharge capacity. What we usually call battery capacity refers to discharge capacity. It is not difficult to see that during the charging and discharging of lithium-ion batteries, lithium ions are in a state of movement from cathode to anode, then to cathode.
2. 18650 lithium battery repair method principle
The metal surface of 18650 battery used for a long time will have a certain degree of oxidation, resulting in poor contact between the mobile phone battery and the mobile phone. Lithium batteries last less, while rusty substances on surfaces can be removed with a rubber saffras or other cleaning tool.
Make better contact with the battery. Low temperature can change the electrolyte inside the lithium battery, promoting the chemical reaction of the newly frozen battery. The use process of lithium batteries is actually a charging and discharging process.
During this time, the anode and cathode charges in battery collide with each other. The reason why the battery will become more and more unused is because at normal room temperature, the kinetic energy inside the electron is relatively large. Therefore, battery is in an active state, and the leakage situation is relatively frequent.
The cycle life of lithium batteries is about 600 times. If the number of charging times is increased, the thermal motion of the molecules will gradually destroy the microstructure of the molecular arrangement inside it, and the efficiency of storing charge will gradually decrease.
Once the microstructure of the lithium battery is destroyed, it is impossible to fully recover, and long-term use of this method will accelerate the loss of the mobile phone battery. There are some ways for lithium battery repair.
Deep discharge of mobile phones is to achieve a deeper degree of recharging by depleting internal power, which requires some unconventional methods. Find a way to connect the phone to a small 1.5V light bulb, and the power inside the lithium battery will be transmitted to the small light bulb until it is all lit. After discharging, the phone battery that is recharged can last longer.
3. How to fix 18650 lithium battery
Low temperature can change the electrolyte inside the lithium battery, promoting the chemical reaction of the newly frozen battery. When the lithium battery is placed in a low temperature environment, the microstructure of the lithium film and electrolyte on the surface of the lithium battery.
As well as their interface, will change significantly, resulting in temporary inactivity inside battery and a decrease in leakage current. So after charging again, the standby time will increase.
There is another method: remove the lithium battery, put it on for about a week, and slowly consume electricity, you need to use the machine to completely consume electricity first. Then full flush, estimate that your current charging time must be very short, after flushing, disconnect and flush, repeat several times, absolutely effective. We can know that lithium battery repair is of importance.
4. Common fault of lithium battery pack
For a faulty battery pack, it is first necessary to determine whether it is necessary to do lithium battery repair. We can check this in battery stores nearby. For example, lithium batteries are used almost daily for more than two years. When the capacity decays, the general situation is that the service life is at the end.
When have no lithium battery repair value and can only be recycled as waste products. On the contrary, if the frequency of use is not high, sudden failure (such as undercharging, sudden loss of range, sudden power loss, inability to start, etc.), such battery packs have lithium battery repair value.
5. Lithium battery pack maintenance and analysis
● First carefully observe whether the appearance structure is intact.
Whether there is damage and leakage, burning and hot, and whether there is water ingress, etc., judge the operation risk. To avoid accidents during disassembly and lithium battery repair. Measure the voltage of the charge and discharge port.
● Failure analysis of 0 voltage
If the measured charge and discharge port voltage is 0, first measure whether there is a voltage on the junction protection board. If there is a voltage, detect whether the connecting wire is desoldered and broken. If the line check is normal, it can be determined that the fault point may be on the protection board, and the protection board needs to be replaced or the battery pack charged for testing.
● Protection board failure analysis
The method of detecting whether the protective plate is normal has visual inspection, and whether the components have burned or exploded marks. Different protection board manufacturers have different circuit designs. Generally, the protection board is replaced rather than repaired, and if a component is damaged, it will have a chain reaction.
Cause the performance of other components to decay or damage. If maintenance is not complete, it will bury hidden dangers. The damage of the protection board is generally related to the mismatch of charging voltage and current, and the model, voltage, current and other parameters of the matching charger must be paid attention to when making lithium battery repair.
● Analysis of abnormal volume reduction
The battery pack has a voltage, but not a full voltage. When charging, the charger will automatically jump on the light before it is fully charged, and it will not be able to continue to fully charge batteries. The protection board cable can be removed to measure the voltage of each string of cells one by one, and there may be a string (or strings) of cells in the batteries that has reached the maximum working voltage when the other cells are not fully charged.
As long as the protection board detects that a string of cells reaches the maximum working voltage, in order to prevent overcharging, it will automatically cut off the charging circuit and cause it to fail to charge.
● Unable to charge and discharge failure analysis
The battery pack has voltage but cannot be charged or discharged, and the probability of damage to the internal cells is greater. When the normal cell voltage is already at the highest working voltage, the protection board starts overcharging protection and cannot be charged. However, the damaged cell voltage is already zero or has been lower than the minimum working voltage, and the protection board starts over-discharge protection at the same time.
6. Faulty lithium battery repair steps
● Addition and merger
It is to ensure that the capacity remains unchanged on the basis of the reduction method and lithium battery repair. After the method of reduction is completed, find another 10 cells with the same parameters as the original cells, and increase one in each string. It cannot be mixed with the remaining cells of the subtraction method, and each string must be 4 old cells and 1 new cell, so as to achieve the balance of each string to ensure the consistency of each string and the stability of the battery pack.
● Subtraction method
This method is the simplest and most effective way to remove the damaged string of cells, but it must be clear whether the protection board supports string reduction work.
And some highly integrated protection boards cannot be used to reduce string. It will cause difficult for lithium battery repair. It is also necessary to understand whether the voltage after string reduction can meet the voltage demand of the original electrical appliance, and the charger must be replaced after the voltage and current change after the series is turned off.
● Discharge
Lithium-ion battery packs can be powered on and discharged or connected to resistors. The start-up charge and discharge should be put into the phone start-stop level. Resistive charge and discharge can be connected with the bead long-term charge and discharge relative operating voltage until the bead connection a momentary level will be destroyed. Charge-discharge currents are more suitable for large currents.
● Activation
Connected in series with 12v battery, a small bead or resistor also needs to be connected in the middle of the lithium battery pack, which is more suitable for current limiting. The first step is to select a small current to make the AC current of the control circuit 10mAh for 30~90min, and then increase the current to 2 times the allowable difference of the rechargeable battery.
● Change the cells
The life of the lithium-ion battery pack actually represents that its internal structure lithium-ion battery cells are close to the life limit. The following specific steps were taken: laser cutting with a wallpaper knife around connector of the battery case laser, if the barbed snap place is not solved first, wait for the other joints to open, and then release the scorpion tail side cannula.
Disassemble the lithium battery core with ferrochrome to unload the lithium battery core, and then purchase the lithium battery cell of the relevant specification model, as well as the total number of samples.
7. Conclusion
Lithium battery repair usually refers to the use of physical or chemical means to overhaul the secondary rechargeable battery with reduced performance or non-functional. The use of lithium battery repair can restore the battery capacity, extend the service life of the batteries, and improve the performance.
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