For some info on the RTC battery KTS ML 1220 here is an equivalent.
Note from the write up
Using rechargeable batteries can save you a lot of money. Despite the higher cost of such products, they can have more than 100 charge / discharge cycles, which allows you to replace the same number of ordinary alkaline or salt batteries. The ML1220 battery belongs to this category of power supplies.
From 4 to 8 hours
Not 24 hours
Can I charge
The ML1220 cell is a battery, but charging is not necessary, because the device’s board already has the ability to supply the necessary voltage for its charging to its contacts.
It is not quite right to compare the the more common CR 2032 used in many laptops etc, as they have a capacity of 240mAh compared to the ML1220 of only 18mAh so they can be expected to last considerably longer if doing the same task.
Let’s say 13 times more longevity, so if the ML 1220 could last four weeks the CR 2032 would last a year.
Given the experience of others and myself the CR 2032 last for many years so the ML 1220 would hopefully last 4,5 or six months or more.
But given it’s capacity it does require changing regularly which is where the issue really is. Why does it discharge so quickly and why can’t the main battery look after it?
These are questions I’m submitting formally by the way via a direct letter to Framework proper
By the way the service life of the CR 2032 is only 30 days so that it last for years goes to show how little drain there is in most computers.
The capacity of a CR 1220 is only 40mAh so it may last six weeks and then have to be replaced, so the ML version is ‘better’ as it could last for years.
So size matters, Skinny laptop, skinny RTC battery