Viability of an ML 1220 rechargable battery for RTC | CMOS (11th gen)

Unless you’ve proven out that the ML1220 is faulty, we do not recommend replacement. As we’ve previously stated, the mainboard reset and a full trickle charge should resolve the reported issue. If anyone, after attempting the reset and a full 24 hour charge cycle, continues to run into issues where the laptop is not able to power on, as mentioned by our CEO/Founder, they are to contact Support and we will evaluate on a case-by-case basis. For those that do not want to perform the reset and are replacing the battery simply to have a battery with a full charge, you will likely run into the same issue down the road. If you are having RTC battery charging issues, more often than not, it could be a solder issue with the RTC battery cradle causing the RTC battery to not have a solid connection to the board. But again, this can only be identified by performing the reset and then allowing the existing RTC battery to trickle charge for 24 hours.

If you’ve performed all of the above, and you are still having problems with the battery, please contact Support. Also critical, if you disregard the above and purchase a new RTC battery, DO NOT use a non-rechargeable battery as the mainboard will attempt to push power through it as it is expecting a rechargeable battery.


Thank you for the clarifications, @TheTwistgibber.

Do you still recommend reaching out to support about this, specifically for users who are out of warranty? In my experience, after one troubleshooting email, support detected I was out of warranty and only suggested to buy a new mainboard or post about this issue on the forums. That was the end of their interactivity in our emails.

The possibility of CMOS battery replacement never came up, which (fingers crossed) ended up being the solution. While I will undoubtedly, as you said, run into the same issue down the road, it’s nice to use my laptop like a laptop in the interim, and ML1220s are relatively affordable.

It’s concerning that support didn’t explore whether the ML1220 was faulty. What I want to understand is, was it because Framework doesn’t generally recommend replacing the ML1220, or because I’m out of warranty and therefore not entitled to support? This is why I think it’d be helpful to create clearer expectations for out of warranty users than “contact support, we’ll evaluate case-by-case”.

Overall, there has to be a better way to handle this. The current solution of sending users to bumble around on the forums until they find @nrp’s post (prominently displayed 40 posts deep in a months old topic occupied primarily by malcontents) can be improved upon.

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Very rarely, if at all, is the ML1220 battery faulty, but we have seen solder issues pop up on the RTC Battery Cradle. This is why we ask all customers to perform the reset and then charge for 24 hours. If they run into the issue AFTER the 24 hours of charging where the laptop won’t power on again, that means that there might be a problem with the cradle itself. While we can’t rule out a bad battery, it’s extremely rare, and while swapping the battery might temporarily mitigate the issue, it isn’t actually solving anything as the battery will continue to drain if there’s a trickle charge issue. Also, 3rd Party RTC Batteries are hit or miss as far as their performance and can cause issues. We have a very small stock of RTC coin cells at our repair center in the US, and we’re only sending those out after we’ve eliminated all other potential sources of failure. In most cases, we swap the mainboard and then evaluate the returned board for any issues (then refurbish it). For those just outside of warranty, we still recommend contacting Support and I’ll remind our staff to escalate should someone be outside of warranty. All submitted information will be reviewed at that time.


@Twistgibber - are the expected number of discharge-recharge cycles and/or expected lifespan by time (years, presumably) for the ML1220 documented someplace? Thank you.

I’ve pinged our engineering group to see if we have that available. Thanks for your patience while I await their response.


That’s going to be a tough answer.

Li-ion batteries are incredibly variable by use.

  • You may note reports that charging from 40% to 80% may only use 10% of a cycle not the 40% you’d expect
  • Charging from 0 to 100% may be recorded as 1 cycle by there is the possibility of serious decline when a battery goes to zero
  • Then you have the temperature, so someone using the computer in a cold environment and not playing games etc. with keep the battery more ‘healthy’

The battery specs say 100 cycles.
So if the max life of one charge is 21 days then in a year it will have dropped about 20% assuming a full cycle every three weeks.

So in theory it could last 2 or 3 years with and increasing but with a shorted span so only 18 or 19 days after a year etc.

This is very unlikely to work out but you never know.

Equally unlikely is that although 99% of the time I use my laptop plugged in that the ML1220 is going to last a very long time.

An example is I am keeping data on my main battery wear.

  • There is a recorded <60 cycles in ten months.
  • The specs say 1000 cycles over 2 years for a 20% lost i.e. from 55Wh to 44Wh

At my rate of use I doubt I will use 100 cycles in a year so it could be imagined that I’ll lose 20% in ten years. So incredibly unlikely.

So although there are specs for batteries I have yet to see data on how those claims are made, data that can be verified as user practical.

I will be awaiting the feedback with interest.


There is a post above linking to the data for a Panasonic ML1220 that link is a 404. It seems Panasonic do not make the ML1220 anymore.

Here is a link to the data on my site a PDF


I have found a data sheet for a Maxell ML1220 which states a cycle life of 1500 if only discharged by 10%.
Also Available on my related site

So according to specs above
a 10% usage and 1500 cycles
a 20% usage and 500 cycles

Extrapolate for usage in the 11th Gen where the ML1220 can only be charged when connected to power
a 30% usage 166 cycles (i.e for 30% or approx 6 hours of use not plugged in) then the cycles may only be 167 i.e. 6 hours of such use every other day for a year

a 40% may provide only 55 days

Sadly it seems there is a discharge of around 0.3mAh which means if you don’t use it before then you have just done a 100% cycle

  • 100% it may not recover very well and if it does then you may be lucky to get 10 cycles. Still it could last for 10 x 3 weeks ???

Mine has gone really bad. Had a few stop starts. Once I got the laptop up and running I’ve left it on charge for 18+ hours and then it still wont fire up the next day. I know its the CMOS cos the underclock/battert limit etc. keeps getting wiped out. So even nearly a days charge wont do it. I’m now going to leave it for a a full 24 hours and see what happens. If it powers on then I’ll leave it 48 hours and see if it works again.

@Jason_Dagless If you’ve followed the mainboard reset step-by-step, charged for 18 hours afterwards, and still have issues with reset/power, something else is wrong, and please contact Framework Support. If you’ve checked the RTC Battery cradle, and it seems it’s solidly connected to the mainboard, we can send out one of our service RTC batteries from our repair center. It’s absolutely critical that the reset and charge is done to diagnose and it seems like you have. There could be something else going on as well, so please contact Framework Support.


No worries. I’ll do the 24 hour charge and then do an internal test on the battery socket and get back to Support if required.

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Sadly that should be fine, and 24hrs more so.
It would be useful to know what charge rate there is for the ML1220 as we ‘know’ the capacity is around 17/18mA/h

The nominal discharge is 0.03mA/h (Panasonic data) 0.1mA/h (Maxell data)
Days to discharge @ 0.03mA/h = 21 days @ 0.1mAh = 7 days

Given a charge rate of 1mA/h the battery would charge in 17 to 18 hours.
However when the battery is below 10% and above 90% the charge rate is likely to be dramatically reduced, hence the 24 hour advice to charge.

However depending upon it’s 'life; cycle that could be dramatically reduced.

As the charge rate depends upon the voltage even a small resistance cause by tarnishing, low contact pressure, poor soldering etc. will mean the battery never reaches it maximum voltage, yet the charge will stop prematurely.

This is why Framework ‘more or less insist’ that a) It is charged for 24 hours and b) the battery should not be replaced as it may be a fault external to the battery.


Yeah the fact that the battery cradle keeps popping up seems to me it’s a reasonable size batch.

If my issues are purely the CPU bug then I can work around that but if it’s a bad cradle then I want that sorted before I pass it on.

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EDITED: Ahh, you meant popping up as in being mentioned, not “popping up” off the board. Yes, let’s figure out what the root cause is.

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I shall report back. :thinking:

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Yeah, this is what happened to mine too. Mainboard resets became a routine part of my boot process if I let it power down for longer than a minute (even after letting it sit on the charger all week). Laptop used to work fine for 10 months until I left it unpowered/unused in my backpack for a month, which I assume killed the RTC battery.

My workaround was to avoid turning off the laptop and always travel with the screwdriver and a SIM eject tool handy for booting.

If you’ve performed the mainboard reset, let it charge for 24 hours, and are not consistently leaving it unused/not on a charger for weeks/months, and are seeing the reset consistently, please contact Support. Either the battery can no longer hold voltage or there’s something wrong with the RTC cradle. The Support agents have updated instructions to assist, even outside of the warranty period.


Yes that can easily happen. It was a design oversight not to have battery, in the 11Gen being charged from the main battery. This maybe why support are happy to help in this situation even though the warranty has expired. Hope they keep that up for the 11Gen for - a long time.

OK More info on the ML1220

This is taken from

In case of the datasheet URL becoming unavailable I also have a copy

Note the recommended usage is from 80% to 100% (maybe 77% to 78%) and clearly taking the battery below 20% is a no go.

With nominal drain of 0.03mA/h and 20% of capacity being around 3.5mA/h the 11th Gen should not be off mains power for longer than 166 hours or again 6 to 7 days.

This is a generous ‘advice’ as the battery will be loosing capacity from day 1 and if not treated extremely well will be degrading rapidly.

So a design that really only permits the laptop to disconnected from the mains for a week, without damaging the ML1220 is quite an oversight, and arguably not fit for the purpose that many customers may unwittingly put the laptop too. i.e. leaving it not plugged in for 6 days


Interesting, but unplugged for 6 days max just sounds too short. I mean, when brand new, how many days did these laptops spend in inventory and shipping to customers? Why did that time unplugged not kill the RTC?

I enjoyed 10 months of hassle-free use after my laptop’s delivery, and it sure felt like I waited a long time for it to arrive at my door.


Yes that’s a relevant point.

The 6 days is the time it takes to deplete the Ml12200 by some 20% so it can travel for two or three of weeks and still switch on.

A perfect battery can last 3 weeks. Some people have a problem and maybe that is due to a slow delivery from assembly to delivery.

There’s also the issue that the laptop is delivered in a state where it will not turn on without first connecting it to a power supply. This may have the effect that before that so much of the hardware is disconnected electronically that the ML1220 has a far reduced load. That would be nice to know too :slight_smile:


UPDATE: Nirav’s update on this is here with links to the datasheets: Viability of an ML 1220 rechargable battery for RTC | CMOS (11th gen) - #453

Just to provide an update, this is being tracked down in coordination with our team in Taiwan as we want to make sure we’re providing the most accurate information. I’ll update here once I have the appropriate information to share. Thanks for your continued patience.