Looks like it might be something like this:
https://uk.farnell.com/panasonic-electronic-c … 2330/dp/1298256

In which case, I think it's spot welded to the carrier, so you'll probably have to unsolder the current one. Or maybe just cut the current battery out, then solder a normal battery holder in its place.

snufkin wrote on 2021-06-29, 21:03:

Looks like it might be something like this:
https://uk.farnell.com/panasonic-electronic-c … 2330/dp/1298256

In which case, I think it's spot welded to the carrier, so you'll probably have to unsolder the current one. Or maybe just cut the current battery out, then solder a normal battery holder in its place.

So I need to heat up the top part that is holding the battery down,remove the battery, put a new battery in and then add a small amount of solder between the top holder and new battery? Something like that anyway?

rick12373 wrote on 2021-06-29, 21:13:

snufkin wrote on 2021-06-29, 21:03:

Looks like it might be something like this:
https://uk.farnell.com/panasonic-electronic-c … 2330/dp/1298256

In which case, I think it's spot welded to the carrier, so you'll probably have to unsolder the current one. Or maybe just cut the current battery out, then solder a normal battery holder in its place.

So I need to heat up the top part that is holding the battery down,remove the battery, put a new battery in and then add a small amount of solder between the top holder and new battery? Something like that anyway?

If it's a spot weld then heating it won't work. I think welding is used because it actually heats the parts less due to shorter contact time. If you've got a reasonable soldering iron then I'd try unsoldering the battery from the PCB. Could be tricky as it'll be connected to at least the ground plane of the motherboard, which sucks heat away. Might be easier (though it'll look messy) to snip the battery off, then solder some wires between the remaining stubs and a cr2032 holder.

Sounds like cutting the old one out and adding one of these might be the best option. Not sure why it has space for 2 batteries though.

https://www.amazon.com/LAMPVPATH-cr2032-Batte … 25002958&sr=8-6

rick12373 wrote on 2021-06-29, 21:45:

Sounds like cutting the old one out and adding one of these might be the best option. Not sure why it has space for 2 batteries though.

https://www.amazon.com/LAMPVPATH-cr2032-Batte … 25002958&sr=8-6

I think that puts 2 cells in series, so produces 6V, which you don't want. I can't just find a ready wired single cell holder, so I'd just look to get a PCB mount 2032 holder, then solder some wires between the holder and the motherboard. Make a note of which pins on the motherboard are +ve. Cover the exposed pins with heat shrink tube or some tape, then some double sided tape or glue to fix the holder in place somewhere safe.

snufkin wrote on 2021-06-29, 21:54:

rick12373 wrote on 2021-06-29, 21:45:

Sounds like cutting the old one out and adding one of these might be the best option. Not sure why it has space for 2 batteries though.

https://www.amazon.com/LAMPVPATH-cr2032-Batte … 25002958&sr=8-6

I think that puts 2 cells in series, so produces 6V, which you don't want. I can't just find a ready wired single cell holder, so I'd just look to get a PCB mount 2032 holder, then solder some wires between the holder and the motherboard. Make a note of which pins on the motherboard are +ve. Cover the exposed pins with heat shrink tube or some tape, then some double sided tape or glue to fix the holder in place somewhere safe.

Yeah the two cells is strange, although on that listing it shows the thing connected to what looks like a motherboard.

I suppose this would work https://www.amazon.com/CR2032-Button-Battery- … 5003805&sr=8-13 .

If you get the black one it should be easy to see which wire is the +.

Why not just use the proper pin header marked Battery / J11 for the external battery replacement pack, or make your own if you can't find it or an equivalent- saves any board-level soldering

Ah. Yes. That makes more sense. You mean just plugging something like this: https://www.smallbattery.company.org.uk/sbc_840.htm on to the obvious header marked 'battery'? I was obsessing about changing the battery so didn't even notice that. I expect the motherboard has diodes to protect the existing cell from being charged. Do you think it would be a good idea to remove the existing battery anyway, in case it leaks?

snufkin wrote on 2021-06-30, 07:37:

Ah. Yes. That makes more sense. You mean just plugging something like this: https://www.smallbattery.company.org.uk/sbc_840.htm on to the obvious header marked 'battery'? I was obsessing about changing the battery so didn't even notice that. I expect the motherboard has diodes to protect the existing cell from being charged. Do you think it would be a good idea to remove the existing battery anyway, in case it leaks?

I bought my external battery from that exact website 😀

In my case I left the original battery, but I might remove it later on by unsoldering.

If you have FB and you are interested, please join https://www.facebook.com/groups/compaqpresariocds500series
You will have a lot of people that can help you with the Compaq CDS 5xx.

Ahh, awesome information. Thanks!

I'd just shrinkwrap 3 Energiser Lithium AAs and worry about it again in another couple of decades.

edit: though they don't seem as cheap as they were 5 years back when they were pushing them for digital cameras, or I got the pack on sale.