With several old Thinkpads (both IBM and Lenovo of times) I know that you should always have a handful BIOS batteries in the drawer. For most laptops (or even normal motherboards) are the CR2025 coin cell. Now, when I wanted to do for a friend an old T61 refloat I was surprised to find there a CR2032 with soldered cable in a crazy holding construction. The expansion proved a little difficult because of the associated plug-in connection is almost hidden in the housing. Well, somehow it went but without the entire housing to disassemble.
The delivered CR2032 with plug of EUNICELL corresponded technically developed the original (the cable seemed just a bit longer) and was therefore easily be incorporated into the device. The voltage corresponding to a normal CR2032 from the blister pack, ie there are no superimposed remainders. I was even inclined to solder something together yourself, but here not worth it and would not be optimal.