1. No voltage or abnormal voltage

If there is no voltage or abnormal voltage, we should adjust the multimeter to the DC 20V position, and then use the red meter pen to touch the positive pole of the lithium ion battery cell, and the black meter pen touch the negative pole of the cell. If the multimeter shows that there is no voltage or the voltage is very high If it is low, it proves that the battery is damaged. Pay attention to check whether the positive and negative poles of the protection board are reversed. If they are reversed, the charger is equivalent to forced over-discharge when charging the lithium-ion battery pack.

2. No overcurrent protection

If there is no over-current protection and other phenomena, first check whether the circuit of the over-current detection pin is defective, and if there is any, replace the protection IC.

3. No resistance or excessive resistance

It is necessary to find the reason from the identification circuit of the resistance pad, and check whether the identification resistance is disconnected, whether the resistance is incorrectly attached, whether there is a short circuit or an open circuit, etc.

4. Can't charge

Use the multimeter switch to select the 20v gear, and then use the red meter pen to touch the positive electrode of the battery or the protection board. If the multimeter shows voltage, we will analyze it according to the following conditions: whether there is an output voltage and whether the battery voltage is normal Condition. If the above voltage is not normal, we can basically judge that the protection IC or MOS tube has been damaged. At this time, it is enough to replace these two components.

5. No internal resistance or excessive internal resistance

If there is no internal resistance, check whether the pins of the MOS tube are damaged, and if so, just replace the MOS tube.

If the internal resistance is too large, it is necessary to use a probe to contact the electric fish lithium-ion battery protection board to detect whether there are reasons such as poor contact or excessive oxidation. Also check whether there are more nickel chips on the battery core. If the number of nickel chips on the battery core is too much, it will cause excessive internal resistance.