Help me restore access to my DOS machine's drive

[racketboy]

A 2430 battery is what's in there now (with some wiggle room)?

Correct -- very minimal wiggle.

[Ziggy]

Hmm, that's funny that there's wiggle. A 2430 or 2450 is the largest diameter coin battery I'm seeing in quick searches. Unless it's some massive uncommon battery size that hasn't been produced in years?

Also, this just dawned on me, you should check to make sure it doesn't use a rechargeable battery. If it does, you definitely do NOT want to use a normal non-rechargeable battery in there. It could explode. Easy enough to test. Do you have a multimeter? You want to use the DC voltage settings. If your meter doesn't auto range, you're looking for a low voltage, maybe 2~5v. You can see in the empty battery holder there are two metal clips, one for the top and one for the bottom of the battery. Maybe put a piece of cardboard or plastic in there so you don't accidentally touch them together (that might fry something on the board). Anyway, you'll wanna touch one probe from the multimeter to one of those clips, and the other probe to the other clip. The bottom should be negative (black probe) and the top should be positive (red probe) but it really doesn't matter if you get it reversed (you'll just get a negative reading on the meter). You'll need to power the board on, of course. While the board is powered on, if the battery holder reads 0v than that means it takes a non-rechargeable battery. If it's reading a any voltage, then that means you need a rechargeable battery.

By the way, in the last pic you posted, I believe that battery is upside down.

edit: OK, I just looked at the PDF that you posted again. It specifies "two 3v lithium batteries" so it would be a CR type battery. Meaning it's non-rechargeable. So really, you can put any 3v battery in there. The size is just the size (and capacity) but the voltage will always be 3v, so nothing is gonna blow up. If you have a second 2430, I would try installing two of those in there and see if the CMOS holds. The positive side of both batteries should be facing up (so that the negative side of the top battery is touching the positive side of the bottom battery).

[racketboy]

Great info and great eye on spotting that in the PDF!
I'll plan on giving that a try! Thank you!