Dell XPS 15 9560 (2017) CMOS Battery

Does anyone know the exact type of CMOS battery needed by my XPS laptop?

Some online information is telling me I need an ML1220 rechargeable CMOS battery, whilst others mention a CR1220.

I’ve found some batteries on Amazon and eBay which say they are compatible with my XPS 15 9560 (they include that short lead with the battery encased in a cover).

I’ve got that annoying issue of the laptop starting up with an error that it doesn’t know the time (it resets to sometime back in 2021). I have to go into the BIOS each time to set the time before it will then reboot into Windows.

I removed the 97Wh battery a few years ago as it wouldn’t last very long. I’d read you can start getting battery swelling issues on old degraded batteries. As such, I’ve been running off the power lead for a while.

I’ve gone through the service manual and some online walkthroughs and videos about taking the motherboard out to turn it over as the CMOS battery is on the other side ☹

I’ve previously had the fun of replacing the thermal paste on the CPU and GPU due to losing performance and overheating. The laptop got a lot better after I did that, so getting back into the CMOS battery is going to be a little worse than that job…

Do we know if the XPS 15 9560 needs a rechargeable CMOS battery?

If so, does the ML1220 actually need the main battery installed to keep charging off – else it will go flat again?

In the above cases, it would imply I might need to also invest in a new 6GTPY battery to prevent any new ML1220 from dying due to lack of continual power source.

Why doesn’t Dell sell approved replacement CMOS batteries?

Any knowledgeable advice about all these issues/facts I’m unsure about would be much appreciated.

Many thanks!