Silly Question - CMOS Batteries

Hey gang, odd question...

I'm giving my nephew a new old computer I'm rehabilitating for him - A Dell Latitude D530 with a Windows 10 upgrade that's working great - 4GB RAM and a 500GB HDD, which will replace an older D510 I gave him a while back, since XP is unfortunately being squeezed for its usefulness, now that folks like Chrome are starting to end service on it as well.

Here's the kicker - the guy I got this carcass from gave me all the goodies for it save one - the CMOS battery (I won't tell ya the weirdness of it all when I tuned on this very Dell computer and got an HP logo... well, at least I know where he got the HDD from). Unlike most confusers from Dell of the period that use a wrapped coin or button cell battery that plugged in a jack on the board, this one has a good old fashioned coin-style battery holder in the memory expansion bay. Mine is very empty, so every time I remove the battery and power pack, the time setting skips a beat. Oddly, the only thing the Dell Service Manual and the Owner's Guide states is HOW TO REMOVE the dang thing, which I would hope any of us would know how to do. At not place in either of these guides does it say what TYPE of battery it is! Is it a 1.5V, a 3V... a CR16XX... WHAT?

Worse, you can't Google it either. Google keeps trying to redirect you to the D630, which has a completely different system, and just to add idiocy to lunacy, someone once asked another question-site about a mythical Inspiron D530 (which never existed), making the traditional search system more useless.

SO... my question to you all is what type and size CMOS battery goes into a Dell Latitude D530?

Thanks guys,

A-N