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1. The lithium battery protection board problem causes the lithium battery to not be charged
There are two simple ways to determine the problem of the lithium battery protection board.
Method one, without the protection board, directly charge the lithium battery PACK, that is, the lithium battery pack B and B- direct charging, if you can charge, that is, you can ensure that the lithium battery pack is normal without the protection board, but after the protection board is charged, it can not be charged, which shows that the lithium battery protection board is faulty.
Method two, replace the protection board, if you replace the new protection board, you can charge, but the old protection board can not be charged, it means that the protection board in the previous lithium battery pack is faulty.
If it is the problem of the lithium battery protection board, most of the charging MOS of the protection board is faulty, or the charging fuse is broken by a large current, or the IC of the lithium battery protection board is damaged.
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Solution: The lithium battery protection board failure, resulting in the lithium battery pack can not be charged, the most direct solution is to replace a new protection board.
If there is no completely new protection board, you can detect the specific fault point of the protection board, such as MOS tube, resistor, capacitor, IC, fuse and other components, detect the specific fault point of the protection board, and then correspondingly replace the components of the protection board, or PCB circuit, it can be solved.
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2, the lithium battery PACK process problems lead to the lithium battery can not be charged
This reason includes the internal process of the lithium battery PACK as well as the charging loop. PACK process includes welding during soldering, series nickel strip rust disconnection, assembly circuit short circuit and so on. The way to determine the PACK process problem is to open the lithium battery PACK, observe each process point with the naked eye, and carry out a charging test after completing basic observations such as virtual welding, fake welding, etc., so that you can quickly determine whether there is a problem with the PACK process.
The process problems of the charging circuit, including the poor plug, and the poor plug welding line, etc., such as the DC head is the charging port of most small power lithium battery products, if the DC head is poor or the DC plug welding position is virtual welding will lead to the lithium battery pack charging circuit problems, the lithium battery pack will not be charged.
The solution is to repair the spot where the welding is false. If the problem is the charging port, replace the charging port and re-weld it.
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3. The lithium battery cell problem causes the lithium battery to not be charged
If it is the battery core problem that causes the lithium battery pack to be charged, there are two ways to judge,
One is to charge each string of cells in the lithium battery pack, if a string of cells are found to be unable to charge, it indicates that the lithium battery cell is faulty, and it is decided to ask the lithium battery cell problem!
The other is that each string of cells can be charged, but the voltage difference of each string is relatively large, we also say that the consistency of the lithium battery pack is large, which will also lead to the lithium battery pack can not be charged. If the pressure difference of the lithium battery pack is large, it can also be determined that the problem of the lithium battery cell caused the lithium battery to be charged.
For example: ternary lithium 36V battery pack, 10 string combination, if there is a string of cell voltage is 4.2V, and the other string of voltage is about 3.0V. When the charger charges the lithium battery pack, although the other strings are about 3.0V and the voltage is very low, the 4.2V string will reach the overcharge protection value of the lithium battery protection board in the moment of charging, and the protection board will start the overcharge protection and disconnect the charging MOS tube, resulting in no charging.
Solution: The problem of the battery, if the battery can not be charged, the battery needs to be replaced; If the cell pressure difference is large, you can flatten the battery voltage of the lithium battery pack and then continue to charge.