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TitusVorenus

macrumors member
Original poster
Mar 28, 2011
67
7
I use my MBP primarily as a desktop with an external monitor. I've got about 300 charging cycles on it and my battery capacity is down to 3800 from 5088 in 3 years, or 25% reduction in function and I've got the "service battery" warning. My monitor has a usb C hookup which also powers the laptop. I don't leave it plugged in when I'm not using it.

Is this battery degredation normal for a 3 year old machine? Would some drain/charge cycles reset the battery health and capacity?
 

mikzn

macrumors 68040
Sep 2, 2013
3,005
2,291
North Vancouver
That is not Normal 300 cycles is not much - batteries can usually last 700 to 800 cycles

On the other hand, many things can affect the battery like heat and extreme cold etc - not a good idea to ignore that “service battery” warning - I ignored that warning on my MacBook Pro and kept procrastinating about the battery replacement and finally it failed due to swollen batteries pushing against the motherboard - luckily I was able to replace the battery and it started working again

See my previous post and pictures here

FWIW - probably good to keep the power connected when using the extra monitor
 
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CMMChris

macrumors 6502a
Oct 28, 2019
850
793
Germany (Bavaria)
It's not mainly about cycles but also how long you leave it plugged in at 100%. Battery chemistry doesn't like that all. These days, Apple has some optimized charging which tried to identify your usage behavior and limits charging to 80% in such cases. But this doesn't work well and even 80% can be too much for extended periods of time.

In the future, disable Apple's optimized charging and try to use AlDente to manually limit your charge when needed. Best is to limit it to something in between 60 and 70% when hooked up to a charger for extended periods of time. This gives great results for batteries that are mainly living on the desk without being used much.

You can try giving your current battery some life back by cycling it between 20% and 100% a couple times and also doing a calibration. But you surely won't get it back to the original state.
 
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Fishrrman

macrumors Penryn
Feb 20, 2009
28,594
12,700
If it was me...

I'd have the battery replaced by Apple using their $199 option, if it's available where you are.

I'd also pay attention to what CMMChris wrote.
It's not a good idea to just leave the charger plugged in all the time.
 

TitusVorenus

macrumors member
Original poster
Mar 28, 2011
67
7
It's not mainly about cycles but also how long you leave it plugged in at 100%. Battery chemistry doesn't like that all. These days, Apple has some optimized charging which tried to identify your usage behavior and limits charging to 80% in such cases. But this doesn't work well and even 80% can be too much for extended periods of time.

In the future, disable Apple's optimized charging and try to use AlDente to manually limit your charge when needed. Best is to limit it to something in between 60 and 70% when hooked up to a charger for extended periods of time. This gives great results for batteries that are mainly living on the desk without being used much.

You can try giving your current battery some life back by cycling it between 20% and 100% a couple times and also doing a calibration. But you surely won't get it back to the original state.
I only leave it plugged in when I'm working on it, because the monitor connection also feeds power to it. No way around it with the setup I have. Downloaded AlDente, looks like I'll have to upgrade beyond Catalina to run it. I had been dreading this because the macbook mostly works the way I want it to now.

I'll run some calibrations and 20-80% cycles prior to upgrading the OS and report back.
 

mikzn

macrumors 68040
Sep 2, 2013
3,005
2,291
North Vancouver
Sometimes batteries fail no matter what

FWIW - I also have a second MBP mid 2012 15" i7 - that I use as a desktop (with a 32" external monitor) and it is left on and plugged in 24/7 for 10 years - I just replaced the battery - it was still working - but after the problem with my 2015 MBP I thought it was worth $100 bucks and a good preventive measure - so replaced it after 10 years - hopefully good for another 10 - but it is stuck on Mojave
 
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zorinlynx

macrumors G3
May 31, 2007
8,232
18,044
Florida, USA
This is one of the main issues keeping me from buying a Macbook as a desktop replacement. As much as I'd love my home Mac to be a Macbook that stays at my desk 99% of the time and only goes with me on trips and such, I know the battery will suffer when it's at the desk.

An iMac + a lower-end Macbook for when I travel will have to continue to be the thing to do. Now to wait for Apple to release the larger M1 iMacs! Could be a while.
 
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TitusVorenus

macrumors member
Original poster
Mar 28, 2011
67
7
Interesting update. My 2018 MacBook Pro keyboard failed. I sent it back to apple to be fixed under warranty, and it came back with a new battery as well as a keyboard.
 
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motrek

macrumors 68030
Sep 14, 2012
2,618
306
It's not mainly about cycles but also how long you leave it plugged in at 100%. ...

How long you leave it plugged in is irrelevant.

If the battery is at 100% charge, the laptop won't charge.

Whether or not there's a physical cable connecting it to the wall is irrelevant.

It's not great to store lithium-ion batteries at 100% (which is essentially what the OP is doing), but it's not awful, either.

I've had several MacBooks over the last ~14 years and left them all plugged in almost all the time and their batteries were all in excellent condition after 4-5 years.

I suspect the OP accidentally exposed his battery to high temperatures at some point. Maybe he left the laptop in a hot car or direct sunlight at some point.
 
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CMMChris

macrumors 6502a
Oct 28, 2019
850
793
Germany (Bavaria)
This is nonsense. A charging level of 100% accelerates the chemical aging process of lithium batteries. This is a proven fact that even manufacturers agree on, so there really is nothing to argue about that. Aside from aging faster, it also increases the risk of swollen battery cells. Exactly for those reasons Apple meanwhile introduced optimized battery charging.
 

motrek

macrumors 68030
Sep 14, 2012
2,618
306
This is nonsense. A charging level of 100% accelerates the chemical aging process of lithium batteries. This is a proven fact that even manufacturers agree on, so there really is nothing to argue about that. Aside from aging faster, it also increases the risk of swollen battery cells. Exactly for those reasons Apple meanwhile introduced optimized battery charging.

Like I said, storing a lithium-ion battery at 100% isn't great. (It's not awful, but it's not great.)

That's different from "leaving it plugged in."
 

motrek

macrumors 68030
Sep 14, 2012
2,618
306
Read the message you quoted. Right, it says "leaving it plugged in at 100%". Are you trying to troll me or what?

You can have a laptop plugged in with 100% charge on the battery, and you can have it unplugged with 100% charge on the battery.

The problem is that it has 100% charge on the battery, not whether or not it's plugged in.

So you talking about "how long you leave it plugged in" is confusing. And no, I'm not trying to troll you.
 

motrek

macrumors 68030
Sep 14, 2012
2,618
306
Surely you understand that a laptop's state of charge, and whether or not the laptop is plugged in, are two completely different things.

By saying that it's bad to leave a laptop plugged in, you're going to make people think they should unplug their laptop while they're using it, which is NOT right. Keeping a battery at 100% charge isn't super-terrific for it, but what's guaranteed to wear it out is discharging and recharging it, i.e., using a laptop unplugged.

If you're using a laptop and it's convenient to plug it in, you should always plug it in. That way, the laptop uses wall power instead of putting wear on the battery.
 
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CMMChris

macrumors 6502a
Oct 28, 2019
850
793
Germany (Bavaria)
By saying that it's bad to leave a laptop plugged in, you're going to make people think they should unplug their laptop while they're using it, which is NOT right.
This is the last reply you get from me since I am not interested in wasting my time. I never said what you claim. You quoted part of my message, and totally ignore the rest, blaming me for saying something I did not say. I link it for you again to read so you and others can see that what you are saying is utter ********. I clearly wrote that the CHARGE SHOULD BE LIMITED when using it plugged in for extended periods of time. I never wrote the laptop should always be unplugged while using it.
 

motrek

macrumors 68030
Sep 14, 2012
2,618
306
This is the last reply you get from me since I am not interested in wasting my time. I never said what you claim. You quoted part of my message, and totally ignore the rest, blaming me for saying something I did not say. I link it for you again to read so you and others can see that what you are saying is utter ********. I clearly wrote that the CHARGE SHOULD BE LIMITED when using it plugged in for extended periods of time. I never wrote the laptop should always be unplugged while using it.

I didn't claim you said anything you didn't say. I said people might read what you wrote and think a certain thing. That's actually kind of the opposite of claiming you said that thing.
 
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