Dear friend, earlier I told you that I ordered a tool from aliexpress. Batteries came with the tool. And unfortunately, some of them "were ordered to live long."
In order to understand what is broken in the power supplies, you need to open them and look. It will be a pity to find out that the breakdown is serious.
I unscrew the screws and, armed with a multimeter, I will look for a malfunction.
In the end, it turned out. That the batteries are alive. The fault is in the charging board. Scroll through the gallery.
No voltage passes through it to the terminals and no charge occurs. Unfortunately, I do not "rummage" in microelectronics. Accum for discharge. In the meantime, let him lie on the sidelines, marked with a cross. So as not to get confused.
Brother, I was saddened by this news. Really and the second "pressed Chinese rice" will disappoint me. We disassemble:
An autopsy immediately revealed the cause of the malfunction. Chinese assembler, poorly soldered connection. That under load (heating), it just soldered off. Scroll through the gallery.
In this case, the solution is simple. We clean the soldering point mechanically, evaporate the joint with acid. And we apply more solder. Scroll through the gallery.
The connection is excellent, even better than the factory one.
Putting this battery back together and putting it on charge, Hurray. It takes charge, which means this battery is working.
From my own experience, I have shown that it is better not to buy batteries of unknown brands. The tool is still possible, but I would not recommend batteries. So as not to fall for these batteries, I will leave link.