A while in coming, but a rechargeable may not work...

I' ve tested an older Gigabyte GA-71xe4 MB battery socket voltages with coin removed:
PS switch off = 0 volts
PS switch on = 1.36 volts
PC booting up = 1.37 volts
Windows running 10 minutes = 1.38 volts

This is under half the typical coin bat nominal voltage of 2.8 - 3.3 volts. 1.36 volts would not charge a battery very well. I note that a typical PC will NOT hold BIOS settings with a battery under 1.2 volts. Some require at least 2 volts. I replace my and my customers coins that test below 2.7 volts and never sell a PC without a coin showing at least 3 volts.