Lessons from the retirement of lithium batteries

I am charging a lithium battery at a time. In order to detect the performance of a new lithium-ion charging board, an ammeter (pointer-type multimeter) is connected between the charging board and the lithium battery to monitor the charging process. After more than four hours of charging, it was found to have an unusual odor. The reason was that the surface of the lithium battery was seriously warmed up, and there was leakage, and the charging power was quickly disconnected until the lithium battery was cooled. The voltage of the lithium battery is only 0.8V, which cannot be charged, and the lithium battery is scrapped. When the lithium battery is charged to the lithium battery, the charging process is controlled by detecting the voltage across the lithium battery. When the charging board detects that the voltage across the rechargeable battery reaches the charging saturation voltage of 4.2V, the battery is stopped. However, since the ammeter is connected between the charging board and the battery, it is equivalent to serially connecting a step-down resistor, and the voltage across the ammeter is measured by the external voltmeter to be 0.3V, even if the voltage across the lithium battery has reached the charging saturation voltage. 4.2 V, the voltage detected by the charging board is only 3.9V, and the lithium battery continues to be charged. Therefore, the lithium battery is overcharged, and if the charging power is not cut off in time. There is even the possibility of an explosion. I hope that my colleagues will never repeat the same mistakes.

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