ASUS Laptop A/C Power Supply Output Doubled
Your battery has dead cell.
Your charger is missing the 1.25V voltage feedback input.
If it is 3wire type, it senses voltage the plug and ratios it down to the Vadj reference voltage. That wire could be broken otherwise internal.  The 41V is typical maximum for universal boost regulators with selectable taps when open loop or the feedback wire is open or shorted to 0V. I hope/trust that the output caps are rated higher than 41V.
I have used this fact to make one 12 to 30V for a 50W LEDS array with a dimmer pot and a couple discrete passives, just like any adjustable SMPS regulator.
It just happens that since laptop OEMs stopped competing with each other with unique voltages and plugs that 19.5V 3.5mm became a standard or perhaps by peer agreement or some industry std. The tolerance on the 19.5 is likely &gt;10% and the laptop will have its own regulators for running without a battery and a separate one for battery CC,CV &amp; cutoff.
If your charger isn’t DC then disregard.