Is it possible to force the PSU to power only the battery?

Question

Charger

Good day.
The problem is the following:
The laptop began to turn off when the charger (memory) is connected.
That is, the battery works fine on any tasks, but as soon as I connect the memory, it immediately turns off.
At the same time, the battery is charging normally, though something is slow.
I measured the output voltage on the charger, it gives out about 12V instead of the declared 20V. could this be causing the problem?
Now the situation is such that you need a computer and there is no time to wait until a new memory arrives.
The built-in utility makes it possible to turn on / off the process of charging the battery, that is, there is some kind of control mechanism for all this.
so the main question is whether it is possible to somehow force the memory to charge the battery, and power to the motherboard so that it comes from the battery, and not from the memory?
PS.
you can not write about overheating and thermal paste - I ruled it out right away.

Answer 1

12 instead of 20 - there may well be a problem with the PSU, try it on a known working one.