Optimized Battery Charging - Best On, Off, or other setting(s)

[RadDave]

Hi all - have had my new M2 Air for just over a week now - in the past I've usually left my laptops plugged to power and the batteries charged to 100% - this morning I noticed that the battery icon in the menu bar was not fully charged - clicked on the icon and saw the battery 'On Hold' at 83% (pic at bottom) - quoted below is the start of Apple's discussion on Optimized Battery Charging (LINK) - seems useful but is the feature really needed, if so, what are the best settings to use - comments and advise appreciated - thanks. Dave

If battery charging is paused or on hold on your Mac​

With macOS Big Sur or later, your Mac learns from your charging habits to improve the lifespan of your battery.

In macOS Big Sur or later, Optimized Battery Charging is designed to improve the lifespan of your battery and reduce the time your Mac spends fully charged. When the feature is enabled, your Mac will delay charging past 80% in certain situations. Your Mac learns your charging routine and aims to ensure that your Mac is fully charged when unplugged.

On Mac computers with Apple silicon or the T2 security chip, Optimized Battery Charging is on by default when you set up your Mac or after updating to macOS Big Sur or later.

.

 

[MacInWin]

Just leave it as it is. When it detects that it has been on mains power for a while, it will let the battery drift down to 80% or so (mine is currently at 78%). When you know you are about to go mobile, you can direct it to charge to full. It will also return to charge to full when it is first re-attached to mains power, then learn again after a few days. The AS machines don't use as much power as the Intel versions, so unless you know you'll need a full day without charging, 80% is plenty. Here is what mine says on my MBP:


You can see that it says "Charging On Hold (Rarely Used On Battery)." That is the battery life extending protocol. Lithium batteries don't like to be held at 100% all the time, also don't like deep discharges, so keeping it in the 80-40% range will increase the overall life of the battery.

Bottom line: Leave it at what Apple set.

 

[RadDave]

Thanks Jake - will leave as is and observe how the battery is handled with this feature. Dave

 

[MacInWin]

Thanks Jake - will leave as is and observe how the battery is handled with this feature. Dave

I think you will find it works well. Just as an aside, I've not found a way to turn it off. I suppose it can be defeated by unplugging the Mac for a couple of hours every day to make it think you are mobile, resetting whatever timer is in play, but that seems to me to be a lot of work for little, if any, gain.

 

[Randy B. Singer]

...clicked on the icon and saw the battery 'On Hold' at 83% (pic at bottom) ...

This is normal and desirable.

What lithium batteries like (for optimum life) is to be used as often as possible while NOT connected to the charger, and to be kept somewhere in the range of roughly 40% to 80% charged. Full charges, and full discharges, are especially to be avoided, as they will negatively impact the life of the battery.

All authoritative sources say that lithium ion batteries like it when you "keep the electrons moving." That is, when at all possible you should use your laptop drawing power from the battery, not connected to the charger. (Modern Mac laptops and/or modern Apple chargers are smart enough to make this less important, but even the smartest ones can only use a best guess to try and ameliorate the problem. So if you want your battery to live as long as possible, make sure never to overcharge it, or let it drain too much.)

Some citations:

https://lifehacker.com/5875162/how-often-should-i-charge-my-gadgets-battery-to-prolong-its-lifespan
"...lithium-ion batteries do best when you discharge them for a little bit, then charge them for a little bit."
"Similarly, lithium-ion batteries don't need to be charged all the way to 100%. In fact, they'd prefer not to be—so the 40%-80% rule... is a good guideline. When possible, keep it in that range to prolong its life as long as you can. And, if you do charge it to 100%, don't leave it plugged in."

https://www.popsci.com/charge-batteries-right
"Shallow discharges and recharges are better than full ones, because they put less stress on the battery, so it lasts longer. When your battery is discharging, Battery University recommends that you only let it reach 50 percent before topping it up again. While you're charging it back up, you should also avoid pushing a lithium-ion battery all the way to 100 percent.”

From Apple in 2013-2014 (This was just before Apple was sued over some of their laptops at the time having disappointing battery life. So now they simply don't give guidance with regard to maximizing battery life to avoid legal liability.):
http://web.archive.org/web/20130425025000/http://www.apple.com/batteries/notebooks.html
"For proper maintenance of a lithium-based battery, it’s important to keep the electrons in it moving occasionally. Apple does not recommend leaving your portable plugged in all the time."

https://tidbits.com/2022/05/06/how-...h-fast-charge-and-optimized-battery-charging/
"The inherent problem is that lithium-ion —the current battery chemistry of choice— isn’t particularly stable. It’s more forgiving than older technologies like nickel-cadmium, but it’s all too easy to shorten a lithium-ion battery’s lifespan by:

- Draining the battery completely
- Holding the battery at a 100% charge level..."

 

[Rod]

I agree, I just let it do it's thing. In my mind it can only be good for the battery life in general. I had my M1 MBP on a regular routine where I used it on battery Fri, Sat and Sun mornings then had it plugged into AC all the rest of the time. After a while the charger only charged it to 83% like yours.
Last Sun when I plugged it back into the charger I did not realise that we'd had a power failure o/night so my MBP had dropped to < 40% while on battery. As a result when I did reconnect it to AC it charged to 100% as it is now.
No doubt once my pattern of use is re established it will return to the usual 80%.

 

[PGB1]

This is normal and desirable.

What lithium batteries like (for optimum life) is to be used as often as possible while NOT connected to the charger, and to be kept somewhere in the range of roughly 40% to 80% charged. Full charges, and full discharges, are especially to be avoided, as they will negatively impact the life of the battery.

All authoritative sources say that lithium ion batteries like it when you "keep the electrons moving." That is, when at all possible you should use your laptop drawing power from the battery, not connected to the charger. (Modern Mac laptops and/or modern Apple chargers are smart enough to make this less important, but even the smartest ones can only use a best guess to try and ameliorate the problem. So if you want your battery to live as long as possible, make sure never to overcharge it, or let it drain too much.)

Some citations:

How Often Should I Charge My Gadget's Battery to Prolong Its Lifespan?
"...lithium-ion batteries do best when you discharge them for a little bit, then charge them for a little bit."
"Similarly, lithium-ion batteries don't need to be charged all the way to 100%. In fact, they'd prefer not to be—so the 40%-80% rule... is a good guideline. When possible, keep it in that range to prolong its life as long as you can. And, if you do charge it to 100%, don't leave it plugged in."

Charge your lithium-ion battery devices for maximum longevity
"Shallow discharges and recharges are better than full ones, because they put less stress on the battery, so it lasts longer. When your battery is discharging, Battery University recommends that you only let it reach 50 percent before topping it up again. While you're charging it back up, you should also avoid pushing a lithium-ion battery all the way to 100 percent.”

From Apple in 2013-2014 (This was just before Apple was sued over some of their laptops at the time having disappointing battery life. So now they simply don't give guidance with regard to maximizing battery life to avoid legal liability.):
Apple - Batteries - Notebooks
"For proper maintenance of a lithium-based battery, it’s important to keep the electrons in it moving occasionally. Apple does not recommend leaving your portable plugged in all the time."

How Apple Works Around Battery Chemistry Limits with Fast Charge and Optimized Battery Charging - TidBITS
"The inherent problem is that lithium-ion —the current battery chemistry of choice— isn’t particularly stable. It’s more forgiving than older technologies like nickel-cadmium, but it’s all too easy to shorten a lithium-ion battery’s lifespan by:

- Draining the battery completely
- Holding the battery at a 100% charge level..."

What Randy said about discharging a lithium battery fully is very true, as was explained to me by a pair of battery technology engineers while I was on a project at Ford Motor Company's Product Development Center. It was explained that, although there are many lithium battery types and chemistries, charging fully or depleting fully are very damaging to every type.

Caution!! Boring Science Stuff Ahead:
All chargers have safety circuitry to stop before 100% and all but the cheapest throw-away devices have circuitry to stop operation at a certain battery level. Example: My inexpensive borescope's lithium battery died after being once used until it shut itself off. I examined the circuitry and found that "stop early" was not in the circuit.

Each lithium chemistry calls for different percent-to-full and percent-to-empty optimal requirements. My 2007 MacBook Pro's battery has such limiting circuitry inside (as found during an autopsy when the original battery failed- after many, many years). I'm sure it was optimized by Apple's engineers for the particular battery's chemistry. The one in my lawnmower is a different chemistry and has a different level set.

Lithium batteries have no 'memory' as did early NiCD, so partial charging and discharging is not a problem. (Every battery of every type has a limited number of times that it can be charged. Since electron movement is different in lithium, they act rather conservatively about counting the charge cycles. A charge of 30% counts as only 30% of the number of lifetime charge cycles in the battery. Therefore quick "top offs" are not a problem at all.

Also explained was that temperature has an effect opposite of its effect on NiCD, NiMH, alkaline or even lead acid & AGM: With lithium, the warmer the battery is, the higher the internal resistance is. Therefore the usable amp-hour level available is reduced. The curve on the chart that I was shown wasn't a straight line, it was more like a bell curve. The higher the temperature gets, the faster the reduction in capacity, then it reverses.

Note that the voltage remains the same in varying temperatures due to lithium's chemistry and circuitry.
Anyone who has tried to crank a car in far sub-zero temps or turned on a flashlight with alkaline or zinc carbon in the cold sees the opposite effect- Weak output and reduced voltage. Lithium is more than happy to provide maximum voltage and amperage in the cold.

Paul