If the T60x version of PC Doctor operates the same as the ones I use for the 600X and T2x systems...
If you don't want to sit around and monitor your discharging battery (i.e., time it to see how long it lasts), nor do you want to fool around with booting into Safe Mode, download PC Doctor and run the "Battery Rundown" test (in the Utility menu). It will exercise the system by running CPU and systemboard diagnostics, while at the same time, it keeps track on how long it is running. When it shuts off, charge the battery back up then repeat the process. This should be faster than simply letting the laptop sit idle; the background diagnostics will drain the battery quicker.
So, if you're not around when the system dies, how do you know how long it ran? The next time you run the diagnostic, it will allow you to check what the
previous run time was. It appears that this runtime information is being stored on a memory chip inside the battery.
Since PC Doctor is booted into it's own DOS environment, there is no danger in having an open file on the hard disk when power is cut off.
You will have to create several bootable diskettes or you can create a bootable CD (assuming you have a CD burner and software to write the .ISO file). PC Doctor is listed under the Diagnostics heading here:
Software and Device Drivers - ThinkPad T60, T60p