Hi @megarex ,
By “Power supply was exchanged” I assume you mean the power adapter and not the battery?
If Win10 is installed try creating a [https://www.windowscentral.com/generate-battery-report-windows-10|Win10 battery report] to check the status of the battery.
Check what the percentage of hardware resources are in use in the laptop. It may be that there is a lot going on and the charger cannot supply the load and charge the battery at the same time. Go to Task Manager and check what the CPU, memory and storage percentages are.
Just trying to eliminate things from the mix.