What should I do if the lithium battery protection board has no display, low output voltage, and no load?

With the rapid development of the electric industry, the lithium battery protection board industry has also entered a glorious moment. This is not only an opportunity for the lithium battery protection board industry, but also a challenge for the lithium battery protection board industry. Lithium battery protection boards are becoming more and more popular in life. It can be said that they are everywhere and exist all the time (such as mobile phones, electric cars, electric toys, etc.). As a result, the technology of lithium battery protection board industry becomes more and more challenging. The higher you come, today, the Chinese Chuangfa will learn with everyone what to do if the lithium battery protection board has no display, low output voltage, and no load.

Don’t panic when encountering such unfavorable conditions. First, eliminate the bad battery (the battery is originally without voltage or the voltage is low). If the battery is bad, you should test the protection board. Self-consumption, to see if the self-consumption of the protection board is too large and the battery cell voltage is low. If the battery voltage is normal, it may be due to the failure of the entire circuit of the protection board (components soldering, false soldering, bad FUSE, PCB board internal Circuit failure, via failure, MOS, IC damage, etc.). The specific analysis steps are as follows: (1). Connect the black test lead of a multimeter to the negative electrode of the battery, and connect the red test lead to the FUSE and R1 resistor ends, the Vdd, Dout, and Cout terminals of the IC, and the P+ terminal (assuming electric The core voltage is 3.8V), analyze it section by section, and these test points should all be 3.8V. If not, there is a problem with this section of the circuit.

1. There is a change in the voltage across the FUSE: test whether the FUSE is turned on, if it is turned on, the internal circuit of the PCB board is not turned on; if it is not turned on, the FUSE has a problem (bad incoming material, overcurrent damage ( MOS or IC control failure), there is a problem with the material (the FUSE is burned out before the MOS or IC is activated), then use a wire to short the FUSE, and continue to analyze.

2. There is a voltage at both ends of the R1 resistor. Change: Test the resistance value of R1. If the resistance value is abnormal, it may be a virtual weld and the resistance itself is broken. If the resistance value is not abnormal, there may be a problem with the internal resistance of the IC.

3. IC test terminal voltage Change: The Vdd terminal is connected to the R1 resistor. The Dout and Cout terminals are abnormal, because the IC is soldered or damaged.

4. If there is no change in the previous voltage, test the abnormal voltage between B- and P+ , It is because the positive through hole of the protection board is blocked.

(2) Connect the red test lead of the multimeter to the positive electrode of the battery cell. After activating the MOS tube, the black test lead is connected to the MOS tube 2, 3, 6, 7 in turn. , P-terminal.

1. If the voltage of MOS tube 2, 3, 6 and 7 has changed, it means the MOS tube is abnormal.

2. If the MOS tube voltage does not change If the P-terminal voltage is abnormal, it is because the negative via of the protection board is blocked.