MBP14 battery and the point of "optimized battery charging"

[blahri]

Now that the new macbook pros are capable of very fast charging, I am starting to wonder about battery degradation and the use of "optimized battery charging".

Basically, if I use my macbook pro up to 10% battery when I go to sleep and let it charge, it still charges to 80% at an extremely fast rate. Then it does nothing for about 7 hours before it tops off the last 20%. While I get that basically splitting the charge into two may slightly help perserve battery integrity, this process does not seem very "optimized" to me. I would think, were it truly "optimized" it would instead spread out the charge over the full duration of my sleep, thus charging at a much slower rate.

This would basically be equivalent to an option to turn off fast charging at certain moments, which I certainly would prefer since I plan to use my macbook for a long time and wont notice the difference while I am sleeping.

Does this make any sense, or am I giving Apple's "optimized battery charging" not enough credit?

 

[Erasmus]

You could try using a different charging brick, even if it’s just a cheap one, that maxed out at say 30W. Charge via USB-C port.

 

[Spindel]

Lithium ion batteries do not like to sit at full charge for prolonged periods of time. The optimal charge for longevity is for them to be between 20-30 % and 75-85 % charge.

The point of optimized charging is that your device tries to learn your pattern of charging to minimize the amount of time your device sits att full charge. As you stated. This is the optimized charging.

But here we have a tradeoff, you might need your device/want to use your device outside of your regular routine now and then. And since you still get a fair amount of usage time out of the device at 80% charge it charges it to this level. Fast charging does not in it self degrades the batteries that much, the heat produced when charging/discharging does. So if temperatures are kept under control fast charging to 80 % is not a problem. After about 80 % charge resistance in the cells also start to increase dramatically and more heat is produced, this is another reason charge speed drops off significantly above 80 % charge.

TL;DR Top 20 % of charge capacity is what is worst for the battery, optimized charging just tries to avoid being at that charge state for prolonged periods of time. Fast charging in itself is not by definition bad if cell temperatures are kept under control

 

[blahri]

Nice knowledge, thanks. I can understand this tradeoff to an extend. Still, I think the amount of times people need their devices outside of regular routine (thus likely the middle of the night) at 80% is very limited. If I have to check something quick it would be fine if it were only at 40%.

I have not actively checked the heat during the initial fast charge to 80% on the macbook. But for the iPhone I do notice significantly more heat when the device is fast charging, either wired or via magsafe. Therefore, in that case, I would still prefer if it were possible to limit charge speed via software, although I do not that whether that is really possible.

Also, I do understand how batteries under 20% or over 80% can chemically age the battery, but I do not understand why 20-30% would be better than eg 40-50%.

 

[Spindel]

Also, I do understand how batteries under 20% or over 80% can chemically age the battery, but I do not understand why 20-30% would be better than eg 40-50%.

Once again a trade off. 40-50 % is better for the battery. But the difference between always staying above 20 % and always staying above 40 % is not that great. But below 20 % the "wear" starts to accelerate.

Note that these things are specific to battery chemistry and these numbers are specific to Lithium ion. In the olden days when NiCd was the dominant consumer appliance rechargable battery you really wasn't supposed to charge the battery if it still had charge left since the chemistry would "remember" the last state as the lowest charge state and you'd loose capacity.

There is still a prevalent myth that floats around that you should fully discharge and then recharge new batteries (and from time to time while using a battery product). This is something you should absolutely NOT do with Lithium ion batteries. This could work with NiCd batteries to get more from them but can permanently damage Li batteries.


Lithium ion batteries are really finicky with temperatures. As stated before, don't let them get to warm but also don't put them under load if they are too cold. I live in a cold climate (Sweden) and here a common thing to kill your laptop or phone battery is to, for i e a phone, have it in a purse or outer pocket of a coat on a winter day freezing the battery.

I once did this with an iPod mini (yes I'm old) actually hade it in the inner pocket of my coat (listening to music), was -10°C outside, the pocket got cold since I had a sweater under insulating body heat from the coat pocket. I went from some 4 hour battery time on the iPod to 40 minutes after that day. I should have had it closer to the body in my pant pockets or something.

Same thing can happen to your computer having it in a back pack or bag and taking a longer outside walk somewhere then starting a frozen computer when you arrive where you where going.

General rule, the lithium ion batteries should be above 0°C before being put under load.

 

[wilberforce]

For convenience, I often use a 20W iPad charger to charge my 14”MPB overnight. Plenty fast enough, it typically charges for about 3 or 4 hrs, holds at 80%, then charges the remainder in about 1 hr just before I start using it.

 

[ckuttner]

So I've got my brand new 2020 MacBook Air. On my workdays, I am using one of two video chat platforms in Safari for my patient visits, and drive a VGA monitor that shows my Microsoft Remote Desktop hookup to my clinic's computer.

If I leave my MacBook unplugged, it runs down to maybe 35% over my four hour or so morning, or if I plug it in, its gets to 100% pretty quickly and stays there. Ideally, I'd actively manage this, plugging and unplugging all day to keep in the 40-70% range, but my mind is not on monitoring the battery %.
Wouldn't it be nice if someone, say Apple, would provide the option of letting the battery charge to only 70% or so and just top it up when needed? I could always have the option of setting it to 100% just before an airplane trip, but now that Alaska Air has outlets at the seats, even 70% would really be OK.
So assuming I don't want to buy a new battery anytime soon, anyone have a suggestion for how I deal with my charging? Maybe the answer is indeed a 20W charger?

 

[white7561]

So I've got my brand new 2020 MacBook Air. On my workdays, I am using one of two video chat platforms in Safari for my patient visits, and drive a VGA monitor that shows my Microsoft Remote Desktop hookup to my clinic's computer.

If I leave my MacBook unplugged, it runs down to maybe 35% over my four hour or so morning, or if I plug it in, its gets to 100% pretty quickly and stays there. Ideally, I'd actively manage this, plugging and unplugging all day to keep in the 40-70% range, but my mind is not on monitoring the battery %.
Wouldn't it be nice if someone, say Apple, would provide the option of letting the battery charge to only 70% or so and just top it up when needed? I could always have the option of setting it to 100% just before an airplane trip, but now that Alaska Air has outlets at the seats, even 70% would really be OK.
So assuming I don't want to buy a new battery anytime soon, anyone have a suggestion for how I deal with my charging? Maybe the answer is indeed a 20W charger?

This is where an app called AlDente comes in. Set it to say 50% or 70% and it'll charge to that percentage and stops charging . (Don't forget to disable the Apple's Optimize battery charging thingy)

If you get the pro app it has an option to top up where it'll charge to 100% and then get back to the normal limit

 

[ckuttner]

Wow! Thank you. Great name for the app, too!

 

[white7561]

Wow! Thank you. Great name for the app, too!

Yeh it's a good app I got it even before I bought the new MBP ?

 

[ckuttner]

Yeh it's a good app I got it even before I bought the new MBP ?

I'm intrigued. I'm not finding it on the App Store. Doing a search online gets me pasta recipes and a number of places that appear to have it for download. Who's the developer so I can get the real thing? Setapp?

 

[white7561]

I'm intrigued. I'm not finding it on the App Store. Doing a search online gets me pasta recipes and a number of places that appear to have it for download. Who's the developer so I can get the real thing? Setapp?

This is the website https://apphousekitchen.com/

 

[Isamilis]

Lithium ion batteries do not like to sit at full charge for prolonged periods of time. The optimal charge for longevity is for them to be between 20-30 % and 75-85 % charge.

The point of optimized charging is that your device tries to learn your pattern of charging to minimize the amount of time your device sits att full charge. As you stated. This is the optimized charging.

But here we have a tradeoff, you might need your device/want to use your device outside of your regular routine now and then. And since you still get a fair amount of usage time out of the device at 80% charge it charges it to this level. Fast charging does not in it self degrades the batteries that much, the heat produced when charging/discharging does. So if temperatures are kept under control fast charging to 80 % is not a problem. After about 80 % charge resistance in the cells also start to increase dramatically and more heat is produced, this is another reason charge speed drops off significantly above 80 % charge.

TL;DR Top 20 % of charge capacity is what is worst for the battery, optimized charging just tries to avoid being at that charge state for prolonged periods of time. Fast charging in itself is not by definition bad if cell temperatures are kept under control

Agree. But in my experience, fast charging will always increase battery temperature (even this happened sometimes on regular charger too). So, if battery life is concerned, OP should get lower wattage charger.

 

[Isamilis]

This is where an app called AlDente comes in. Set it to say 50% or 70% and it'll charge to that percentage and stops charging . (Don't forget to disable the Apple's Optimize battery charging thingy)

If you get the pro app it has an option to top up where it'll charge to 100% and then get back to the normal limit

Though some others success, in my case, the app brought my battery health drop from 102% to 92%. I am now, only using plain manual 40-80% rule.

 

[white7561]

Though some others success, in my case, the app brought my battery health drop from 102% to 92%. I am now, only using plain manual 40-80% rule.

I mean technically if you set it to 80% and use it plugged in all the time. It should act the same as using Apple's Optimized Battery Charging thingy where it'll stop it at 80% . It should be fine I think.

 

[Calaveras]

Lithium ion batteries do not like to sit at full charge for prolonged periods of time. The optimal charge for longevity is for them to be between 20-30 % and 75-85 % charge.

The point of optimized charging is that your device tries to learn your pattern of charging to minimize the amount of time your device sits att full charge. As you stated. This is the optimized charging.

But here we have a tradeoff, you might need your device/want to use your device outside of your regular routine now and then. And since you still get a fair amount of usage time out of the device at 80% charge it charges it to this level. Fast charging does not in it self degrades the batteries that much, the heat produced when charging/discharging does. So if temperatures are kept under control fast charging to 80 % is not a problem. After about 80 % charge resistance in the cells also start to increase dramatically and more heat is produced, this is another reason charge speed drops off significantly above 80 % charge.

TL;DR Top 20 % of charge capacity is what is worst for the battery, optimized charging just tries to avoid being at that charge state for prolonged periods of time. Fast charging in itself is not by definition bad if cell temperatures are kept under control

I'm curious about this. I have a toe in the Solar world and the goal there is to always have batteries as close to full as possible. Charge controllers use voltage profiles to vary the amount of voltage sent to the battery bank.
Nowhere did I read anything about batteries wanting to be kept at a lower threshold for longevity.
In fact, they often warn us not to let our batteries spend too much time below 40%.
BTW most of the Li-ION batteries I am familiar with are good for approximately 6-8 years under reasonable use.

 

[Tagbert]

I mean technically if you set it to 80% and use it plugged in all the time. It should act the same as using Apple's Optimized Battery Charging thingy where it'll stop it at 80% . It should be fine I think.

I tried Optimized Charging for the first 4 months of having my MBA. It always stayed at 100%. Never would charge to less. I got Aldente and it stays around 80% all the time.

 

[Spindel]

I'm curious about this. I have a toe in the Solar world and the goal there is to always have batteries as close to full as possible. Charge controllers use voltage profiles to vary the amount of voltage sent to the battery bank.
Nowhere did I read anything about batteries wanting to be kept at a lower threshold for longevity.
In fact, they often warn us not to let our batteries spend too much time below 40%.
BTW most of the Li-ION batteries I am familiar with are good for approximately 6-8 years under reasonable use.

While some of this is from own anecdotal experiences and stuff I picked up from RC-folk (anecdotal) quiet many years ago. There is some research done on this also.

A simple digest is found here: https://news.umich.edu/tips-for-extending-the-lifetime-of-lithium-ion-batteries/


And this is one of many papers on the subject: https://deepblue.lib.umich.edu/bitstream/handle/2027.42/154859/Woody_Maxwell_Thesis.pdf?sequence=1

From the paper some quotes:

Zhang et al. showed that a typical laptop battery stored at 25°C and 100% SoC will irreversibly lose 20% of its capacity each year [15]

Amiri et al. conclude that smaller changes in SoC during increases battery lifetime [66]. Millner specifies that the battery lifetime can be kept in an acceptable range for Plug-in Hybrid Electric Vehicles (PHEVs) by avoiding deep cycles (>60% DoD), high temperatures (>35°C), and high average SoC(>60%)[67]. Marano and Madella show that to reach 10 year/150,000 mile PHEV lifetime, overcharging and operation above 95% SoC should be avoided.

They also show, efficiency and performance degradation if LIBs are discharged or operated at lower than ~25% SoC [54].

That is just from one paper, there is more research on this topic.

 

[yurkennis]

That is just from one paper, there is more research on this topic.

If possible, could you share more papers supporting this statements:

40-50% is better for the battery

The optimal charge for longevity is ... between 20-30 % and 75-85 % charge.

I'm looking for optimal charge level (a) for the days I work near the wall outlet and therefore don't need long battery hours (therefore keep it at 40-50% if it's best for battery health), (b) the days I know in advance I will be on the battery, but keeping in mind that limiting charge to 80% is required for longevity.

Interestingly, the paper you referred to quotes "Cycling 0% to 60%, 750 equivalent full cycles retained 97% initial capacity" as best result among several charging ranges tested for cycling (see page 18).

 

[Isamilis]

Got this from batteryuniversity.com. Personally I tried to charge using the 1st 3 best scenario: 75-65, 75-45 and 75-25, for all my phone, iPad and laptop.
The challenge is to limit the charger up to certain % (usually I put it in charger and forgot to unplug). Therefore I use Charge-Limiter for MacBook and Battery Life Alarm for iPhone and iPad (there are many similar apps). I also don’t use Apple’s optimized battery charging.

Hope this helps.

 

[Internaut]

Regarding Aldente, I think there are bugs, with my 14” Pro, but it Is fundamentally good. Make sure you reboot once a week and, perhaps, do a charge cycle every 1-2 weeks. The Pro version of the app has a calibration mode that does it all for you (but reboot before a full calibration cycle).