So my Dell 486 uses this to power the clock and CMOS RAM:

It's pretty flat, giving out 1.7V and that apparently isn't enough to keep the CMOS settings. Cracking it open reveals this:

It's basically a 9V battery cut in half and the halves wired in parallel. To replace the cells, I took an new 9V battery and opened it up:

Separate the string of cells and rewire as 3s2p:

Unfortunately, the new pack is slightly too fat for the case 🙁

Oh well, then we'll make do with 3 cells. This means slightly less capacity than the old battery, but it still should last for a number of years:

I stuffed in a piece of foam to keep the cells from rattling around:

All done! I used two ranger bands to hold the case together to make future servicing easier:

Better double check before hooking it up. Looks good.

Back in business!