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dgdosen

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If I look at Battery Health in both System Prefs and Coconut Battery, I get different answers (88% vs 82.9%). That would mean each tool's measurement of "degradation" differ by around 40%! (12% vs 17%).

Anyone know why?

battery.png
 
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0906742

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Trust CoconutBattery readings. They are the same what you can pull out of MacOS directly by running a command manually in terminal.
 
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dgdosen

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Battery health is an approximate representation using algorithms.
Well, if I grep the I/O registry, I can see numbers for MaxCapacity and DesignCapacity - and those tie out to what Coconut Battery shows me. That's pretty easy math.

Now, if there's some kind of algorithm that determines the "current MaxCapacity", that may be true, but the most straight forward explanation for the current MaxCapacity is to measure the capacity after charging the battery until it can't take anymore...
 

jav6454

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Well, if I grep the I/O registry, I can see numbers for MaxCapacity and DesignCapacity - and those tie out to what Coconut Battery shows me. That's pretty easy math.

Now, if there's some kind of algorithm that determines the "current MaxCapacity", that may be true, but the most straight forward explanation for the current MaxCapacity is to measure the capacity after charging the battery until it can't take anymore...
The entire battery health and charge levels is an algorithm as you can't have sensors inside battery cells. Numbers on the OS front can match, but it's all done via guess work. I wouldn't think too much into it.
 

0906742

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The entire battery health and charge levels is an algorithm as you can't have sensors inside battery cells. Numbers on the OS front can match, but it's all done via guess work. I wouldn't think too much into it.
There are several parameters that can be used to determine condition and full charge capacity. For example coulomb counting to track current flow in and out of the battery. Also temperature and voltage can be used. I have myself found out in many of my machines that battery health reading starts to drop as soon as battery does not reach the highest possible voltage just as it reaches 100% charge level. For example in my iPhone 12 Pro highest level possible is 4450mV, I had some glitch with my phone where it for some reason stopped charging past 4428mV and battery health started dropping like a rock. After a while it fixed by itself (probably new IOS did the trick) and it started allow charging past 4428mV up to 4448-4449mV and battery health (actual reading) restored back to almost 100%. So following the same parameters in MacBook with correct max mV reading (it is not the same as in iPhone 12 Pro) in mind gives similar results.

Anyway, for such a little charge cycle count, OP's battery health seem rather low to me considering it is supposed to last 1000 charge cycles at 80% health. It would be interesting to hear OP's MacBook charging habits and usage if there is something that could give any explanation to this?
 
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jav6454

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There are several parameters that can be used to determine condition and full charge capacity. For example coulomb counting to track current flow in and out of the battery. Also temperature and voltage can be used. I have myself found out in many of my machines that battery health reading starts to drop as soon as battery does not reach the highest possible voltage just as it reaches 100% charge level. For example in my iPhone 12 Pro highest level possible is 4450mV, I had some glitch with my phone where it for some reason stopped charging past 4428mV and battery health started dropping like a rock. After a while it fixed by itself (probably new IOS did the trick) and it started allow charging past 4428mV up to 4448-4449mV and battery health (actual reading) restored back to almost 100%. So following the same parameters in MacBook with correct max mV reading (it is not the same as in iPhone 12 Pro) in mind gives similar results.

Anyway, for such a little charge cycle count, OP's battery health seem rather low to me considering it is supposed to last 1000 charge cycles at 80% health. It would be interesting to hear OP's MacBook charging habits and usage if there is something that could give any explanation to this?
Again, those are approximations of what's in the cell given what is going in/out or the strength of the cell's EM field. It's not as exact. That said, agreed with your second part. OP is either too unlucky or something wonky is up.
 

0906742

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Again, those are approximations of what's in the cell given what is going in/out or the strength of the cell's EM field. It's not as exact.
Not sure what you mean, but measuring voltage, temperature or even doing coulomb counting is rather trivial thing to do accurately these days, but surely some guesswork may be needed but often outside some glitches those battery health readings go hand in hand with actual battery run times (meaning lower health = lower run time but it is not actually tied to percentage. Like 80% battery health does not mean you can get 8 hours of run times from battery that was 10 hour run time when 100% health, it is more likely half or so).
 
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dgdosen

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I use the machine most weekdays - and usually keep it plugged in. That's probably not ideal for the battery, but I do have 'Optimized battery charging' checked in System Preferences - so the OS can do as it likes.

I'm not complaining about the battery life. It's never been an issue. I was just wondering about the discrepancy in what looks like pretty straightforward math...
 

0906742

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I use the machine most weekdays - and usually keep it plugged in. That's probably not ideal for the battery, but I do have 'Optimized battery charging' checked in System Preferences - so the OS can do as it likes.
That should not be a problem with optimized battery setting but I'm not sure, I don't use it myself nor I keep mine plugged in other than when I actually charge it. But this really makes me think again my plan to sell my MBA M1 and Mini M1 and replace them with a single M1 Pro 14" and use it 99% of the time in clamshell mode connected to external display and charger all the time.

Does battery stay in about 80% charge level when you keep it plugged or does it just hang around 100% all the time?
I understood it is depending on usage pattern and require certain time to be plugged in to kick in and stay there.

I'm not complaining about the battery life. It's never been an issue. I was just wondering about the discrepancy in what looks like pretty straightforward math...
Have you actually kept any track of battery run times between how it was when new and today?
 

izzy0242mr

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Does battery stay in about 80% charge level when you keep it plugged or does it just hang around 100% all the time?
I understood it is depending on usage pattern and require certain time to be plugged in to kick in and stay there.
Just use the app AlDente. You can set it to limit your battery charging to any %. I have mine set to stop charging at 70% since I rarely take it off the charger.

Optimized charging doesn't do that.
 

dgdosen

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I was playing with Ventura - and it stops charging at 80% with some message like 'rarely off charger'. I'm not sure what the setting does in Monterey.
 

0906742

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I was playing with Ventura - and it stops charging at 80% with some message like 'rarely off charger'. I'm not sure what the setting does in Monterey.
If you are willing to take a small risk, you could try switching off "Optimized Battery Charging" and then try to charge battery as full as possible, like letting it stay plugged charger few hours after reaching full 100%. Also probably best testing that when battery is well below 50% before starting to charge. Just don't leave that setting off for a long time if you mostly keep it plugged in, but for a test. I suspect it might actually make battery health reading appear better. Of course that is just my hunch...
 

Mike Boreham

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I use the machine most weekdays - and usually keep it plugged in. That's probably not ideal for the battery, but I do have 'Optimized battery charging' checked in System Preferences - so the OS can do as it likes.

I'm not complaining about the battery life. It's never been an issue. I was just wondering about the discrepancy in what looks like pretty straightforward math...
Some things I said in this post this post are relevant.

Note the health number used by the third party apps goes up as well as down, as in my screenshot in that post.

Apple's number is much more stable and I have never seen it go back up. Apple will only consider replacing the battery when their number drops below 80%, not when the third party app value does.
 

0906742

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Some things I said in this post this post are relevant.

Note the health number used by the third party apps goes up as well as down, as in my screenshot in that post.

Apple's number is much more stable and I have never seen it go back up. Apple will only consider replacing the battery when their number drops below 80%, not when the third party app value does.
Just speculating here for the sake of argument but imagine situation like where "Apple's number" state battery health still 80% while ioreg command could report ~75% and your battery run times could be just like 1/4 of what it was when new. So you don't mind that because their "number is more stable"...?
 

Mike Boreham

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Just speculating here for the sake of argument but imagine situation like where "Apple's number" state battery health still 80% while ioreg command could report ~75% and your battery run times could be just like 1/4 of what it was when new. So you don't mind that because their "number is more stable"...?
HaHa...I would mind a lot....but I am just reporting what Apple will do! Don't shoot the messenger!

My guess is that they have their own algorithm partly because the third party value fluctuates. Otherwise they would have lots of people claiming new batteries as soon as they got a value below 80%.

It is a complex subject so for all I know there may well be very good technical justifications for the Apple number which might take account of more factors.
 
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0906742

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HaHa...I would mind a lot....but I am just reporting what Apple will do! Don't shoot the messenger!
I did not mean to shoot the messenger but to point out few important things.


My guess is that they have their own algorithm partly because the third party value fluctuates. Otherwise they would have lots of people claiming new batteries as soon as they got a value below 80%.

It is a complex subject so for all I know there may well be very good technical justifications for the Apple number which might take account of more factors.
Yeah, there could be something like that too but mostly IMHO that value is also sugar coating things. I'm sure most peoples don't mind that but I'm sure most peoples think that battery health percentage value has actual relation to battery run time, like 80% health means you still get 8 hours out of the battery that used to be 10 hours when new - WRONG, it is likely much much lower, could be even hardly usable in the worse cases.
 
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jdb8167

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Just speculating here for the sake of argument but imagine situation like where "Apple's number" state battery health still 80% while ioreg command could report ~75% and your battery run times could be just like 1/4 of what it was when new. So you don't mind that because their "number is more stable"...?
Apple would still replace the battery even if it reported above 80% in that situation. Getting only 4 hours of battery life on an M1 with 80% life remaining would still indicate a defective battery.
 

0906742

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Apple would still replace the battery even if it reported above 80% in that situation. Getting only 4 hours of battery life on an M1 with 80% life remaining would still indicate a defective battery.
You have actually tested that they replace in that case?
 

jdb8167

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You have actually tested that they replace in that case?
That would require someone I know to have had a defective battery. Since I don't know anyone with that problem, I haven't tested anything. But this is from Apple's website:

Apple Batteries:
Your battery is designed to retain up to 80% of its original capacity at 1000 complete charge cycles. The one-year warranty includes replacement coverage for a defective battery. Apple offers a battery replacement service for all MacBook, MacBook Air, and MacBook Pro notebooks with built-in batteries.

So if you had 80% life left and are well under 1000 charge cycles but were getting 25% capacity, it is pretty obviously a defective battery. If you are out of warranty and didn't purchase Apple care that's a different story. Apple probably won't replace a battery after 1 year unless you pay for service or you have Apple care.
 

0906742

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So if you had 80% life left and are well under 1000 charge cycles but were getting 25% capacity, it is pretty obviously a defective battery. If you are out of warranty and didn't purchase Apple care that's a different story. Apple probably won't replace a battery after 1 year unless you pay for service or you have Apple care.
I'm familiar with that statement, but how would you prove your point in above case if battery health reports 80% and diagnostic cycle shows it is good? From what I read some threads in this forum that seem to be how it goes.
 

jdb8167

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I'm familiar with that statement, but how would you prove your point in above case if battery health reports 80% and diagnostic cycle shows it is good? From what I read some threads in this forum that seem to be how it goes.
Apple will test the battery. They can do more than just look at the number from the system. A battery that degraded is surely going to fail any test.
 

mlody

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Screen Shot 2022-07-03 at 8.41.19 AM.png
I am seeing the same inconsistencies and my system only has 161 cycles. At this rate, I dont even know if my battery will make to 500 cycles before going below 80% regardless if reported by Apple or Coconut. Love the performance of my M1 but the battery seems be on a destructive course. I havnet had a laptop that was chewing thru battery that fast yet.

My wife's MBA M1 also seems to be on the simiar course - at only 35 cycles, Apple reports 98%, Coconut 93.6%
 

0906742

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I am seeing the same inconsistencies and my system only has 161 cycles. At this rate, I dont even know if my battery will make to 500 cycles before going below 80% regardless if reported by Apple or Coconut. Love the performance of my M1 but the battery seems be on a destructive course. I havnet had a laptop that was chewing thru battery that fast yet.

My wife's MBA M1 also seems to be on the simiar course - at only 35 cycles, Apple reports 98%, Coconut 93.6%
Looks a bit like it is rounded up about 5%. Which is actually about similar how battery meter works between MacOS reading vs terminal command when battery is full or nearly full where counter goes to 99% when terminal command returns 94.x%. Anyway, these two should not have any relation between, just my observation (and that is how it works in IOS devices too, however their health meter seems more consistent to me vs iMazing reading up to a certain point).
 
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