What are the lessons of end-of-life lithium batteries

I was recharging a lithium battery. In order to test the performance of a newly purchased lithium charged panel, an ammeter(pointer multimeter) is strung between the charged panel and the lithium battery to monitor the charging process. After more than four hours of charging, an abnormal odor was found. The reason was that the surface of the lithium battery was seriously heated and there was a leak. Immediately disconnect the charging power supply and wait for the lithium battery to cool. The voltage measured for lithium batteries is only 0.8 V and can not be charged. The lithium battery is scrapped. Since the lithium charged panel charges the lithium battery, the charging process is controlled by detecting the voltage at both ends of the lithium battery. When the charged panel detects that the voltage at both ends of the charged battery reaches a charging voltage of 4.2 V, it stops charging the battery. However, due to the connection of the ammeter between the charging plate and the battery, which is equivalent to the string of a pressure-reducing resistor, the voltage at both ends of the ammeter is measured as 0.3 V by the applied voltmeter, even if the voltage at both ends of the lithium battery has reached charging saturation voltage 4.2 V, The voltage detected by the charging plate is only 3.9 V, and it also continues to charge the lithium battery. Therefore, the lithium battery is overcharged, such as not cutting off the charging power supply in time. There is even the possibility of an explosion. Let's hope our colleagues don't make the same mistake.

The page contains the contents of the machine translation.