"yes, i have a method which can upgrade the bios without a fully charged battery..
first of all ,you need to make a bios-update floppy disk and another clean bootable disk with no config.sys and autoexec.bat
then copy the following files from the bios-update disk to the bootable disk: phlash.exe and $0179000.FL1 $0179000.FL3.
and rename the $0179000.fl1 to bios.rom ,$0179000.fl3 to platform.bin
finally use the bootable disk to reboot. And turn to driver letter a:>,just type "phlash<enter>",this program will automatically search for the file platform.bin(the manufacturer specific initialization file) and use the default file bios.rom to update bios. everything will be done just as using the bios-update disk. And this method will not detect whether you use a AC adaptor/battery nor not.
take the risk with your own...this is NOT a safe way to update the bios which IBM recommended.though it really works"
The only problem with this is that the files on my ThinkPad 600E bootdisk are $0044000.fl1 and $0044000.fl2, so what I am wondering is which of these files are bios.rom and platform.bin.