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jeroenvip

macrumors regular
Original poster
May 13, 2017
121
161
299 cycles and the battery is at 81%, 2 days later 301 cycles and the battery is at 89%. Is a battery capable of repairing itself ? Anyone else seen this before ?
 

MacADameYeahNut

macrumors newbie
Feb 1, 2023
9
5
I agree that that is an absolutely crazy jump in in battery capacity! I've owned a zillion Macs through the years, and while I've seen sudden downward drops, I've never seen anything like what you have going on. I'm wondering if there was a software update between the two readings or possibly an extreme temperature change???? Either way, I agree that this is odd battery behavior.
 

MacCheetah3

macrumors 68020
Nov 14, 2003
2,198
1,146
Central MN
As noted earlier, battery measurements are something of an estimation. I tried to find the simplest explanations, though it’s a complicated subject.


I agree that that is an absolutely crazy jump in in battery capacity! I've owned a zillion Macs through the years, and while I've seen sudden downward drops, I've never seen anything like what you have going on. I'm wondering if there was a software update between the two readings or possibly an extreme temperature change???? Either way, I agree that this is odd battery behavior.
Because the chemistry in batteries can vary a lot due to many factors, internal and external, measurements can indeed vary significantly, especially when observed via utilities such as coconutBattery. The problem with coconutBattery is the (reported) values and calculated results (e.g., battery health (i.e., “Full Charge Capacity”)) are for that very moment. Whereas, the macOS/iOS reported max capacity value is calculated over a span of time (and probably even using more parameters), resulting in a better overall guesstimate.


And, therefore, routine — recommended every few months or so — battery calibration is indeed beneficial. Ignore the urban myth the procedure is harmful.


My OCPD causes partially charging devices to feel wrong. Even with the frequent calibrations, you can see how much swing the measurements can have:


iPhone-X_coconutBattery_20240625.png
By the way, iOS currently reports the estimated battery health at 75% on that iPhone X.
 
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ignatius345

macrumors 604
Aug 20, 2015
7,186
11,963
I agree that that is an absolutely crazy jump in in battery capacity! I've owned a zillion Macs through the years, and while I've seen sudden downward drops, I've never seen anything like what you have going on. I'm wondering if there was a software update between the two readings or possibly an extreme temperature change???? Either way, I agree that this is odd battery behavior.
More like odd battery life estimation behavior. The battery didn't magically gain a bunch of capacity over the course of a week or whatever. Give it a few months and average all the data out.
 
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ignatius345

macrumors 604
Aug 20, 2015
7,186
11,963
Also, I find that CoconutBattery very often differs day to day from what System Information has to say about my current battery level and the estimated overall "health" of the battery. I suspect it doesn't have access to all the metrics Apple does, and is just making a rough guess.

Here's a nearly 5% difference in that battery health estimate, as well as a disagreement of nearly 4% on how fully the battery is charged. Whether this is CoconutBattery being inaccurate or Apple's metrics being "optimistic" I don't know -- but it makes me think it's best to take these health estimates with a grain of salt.

Screenshot 2024-06-26 at 6.51.02 PM.png
 
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MacCheetah3

macrumors 68020
Nov 14, 2003
2,198
1,146
Central MN
Whether this is CoconutBattery being inaccurate or Apple's metrics being "optimistic" I don't know -- but it makes me think it's best to take these health estimates with a grain of salt.
I guess, “optimistic” is an okay word to use as there has been a little evidence Apple’s battery health algorithm tends to continue reporting the higher calculated err estimated battery health — that is, until that highest value is no longer the highest value. Of course, all assessments of Apple’s algorithms are also best guess/guesstimates. ;)

Here's a nearly 5% difference in that battery health estimate, as well as a disagreement of nearly 4% on how fully the battery is charged.

View attachment 2392792
As for the state of charge discrepancy… Something of a two-part question… Does the SOT vary when the percentage(s) are below 80%? At the time of the screenshot, has your MBA (i.e., macOS) been reporting 100%/fully charged for a while?

I ask because the overcharge protection is designed to be invisible in macOS, iOS, and iPadOS. However, it can be somewhat observed with tools such as coconutBattery (as these tools simply pull the raw data reported to the OS by the BMS/PMS). In other words, after reaching full charge, the system will stop charging the battery and allow it to be depleted up to about five percent (i.e., dropping from 100% to ~95% or ~80% to ~75% if optimized charging or other limit is set/active). At that point (e.g., 95%), charging will restart. This cycle will continue until the device is disconnected from the charger. During this cycle, the OS only shows “Fully Charged”/100%/80% with no apparent fluctuations, even though there are.

Basically, it’s all about being easier for the user to understand. And, quite frankly, details most users have no need of knowing. Therefore, yes...
it makes me think it's best to take these health estimates with a grain of salt.
… Or in other words, no one should obsess or otherwise stress over these numbers.
 
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