Expected battery life

I have a mid-2018 MacBook Pro 13" that has been my daily use machine since I bought it in November 2018. I have FruitJuice running to keep an eye on the battery status, which for about six months has hovered around 85% capacity. In the last month or so, this has gradually dropped to 80%.

As you can see from the screenshot, I try to run it on battery for at least an hour or two per day rather than just leaving it plugged in almost permanently.

Is this battery condition roughly expected for a 3yo MBP?


Lithium batteries degrade over time regardless of what you do, but using them (discharge + charge) causes them to degrade more quickly. Leaving them plugged in and enabling Apple’s battery management feature is probably the best thing to do for longevity.

That being said, it seems as if having only 80% left with only 291 charge cycles in 2.5 years seems a bit low. I think that you should contact Apple, as I believe that they will replace any battery that gets below 80% within 3 years.


Oh, I always thought that using it on battery for an amount of time regularly would be better long-term than leaving it plugged in 24/7 for weeks on end.

I’ll try my luck with Apple support and see what they say.

I think that there’s so much (often contradictory) information about the care and feeding of lithium batteries that it’s difficult to know what’s best. This is compounded by the fact that the technology has been evolving and what was once true may not be anymore. I believe that the following still hold for lithium based batteries:

  1. Heat causes them to degrade more quickly
  2. Rapid charging causes them to degrade more quickly
  3. Very deeply discharging them causes them to degrade more quickly
  4. Keeping them fully charged for prolonged periods causes them to degrade more quickly
  5. Simply using them causes them to degrade, but of course they’re designed to be used.
  6. Apple generally states that a battery should be able to maintain 80% of its original capacity for at least 3 years or 1000 charge cycles

So basically, using or not using lithium batteries causes them to degrade :laughing: (But the best way to prolong their lives is to keep them charged at no more than 80% of their max charge, something that Apple’s new(ish) battery management features do quite well).


Must be built in obsolescence then as the battery’s 3rd birthday is in 4 days time :smiley:

I’ve turned on Battery Longevity in Settings so will see how it goes. Don’t get me wrong, it’s not an issue as I can still get anything from 6-10 hours usage out of depending on whether I am running VMs or just watching video, listening to music or browsing the web.

I’m a bit confused. Does this mean that I should keep the M1 MBP plugged in when power is available and use battery only when an outlet is not nearby? That would be my preference but I also was under the impression that using the laptop on battery was good for it.

This is starting to feel like food and diet advice. “Eggs will kill you.” “Eggs are good for you.” “Caffeine is bad for you.” “Caffeine is good for your heart and may reduce cancer.” :slight_smile:


This is really about the balance between points 3 & 4 on @ACautionaryTale’s list

Leaving a battery charging all the time will cause it to degrade, but so will repeatedly running it all the way down to near empty. You get optimal battery life by neither charging it up to 100% nor running it all the way down. Actively managing that is a real PITA, so Apple has implemented things like the optimized battery charging checkbox that you screenshotted. With a modern MacBook and macOS version you can get pretty good battery life results by enabling that feature and plugging in when power is convenient and unplugging when you need to use it away from an outlet.


Perfect, that is what I want! In short, use the battery when the battery is needed/necessary. That seems like common sense for a battery enabled mobile device. :slight_smile: Since I like to move about at times to avoid sitting at the desk too long this will mean perhaps an hour a day on battery unless I’m traveling.

This is pretty much what I do most days.

My son has the same MBP as me, purchased about one month earlier, so I will see what his battery status is when he is around.

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Screen grab from my son’s MBP:

Around 100 more charge cycles and another 8% capacity over mine. He spends more time on battery while at university and then plugs in when he gets home.

Looking at the stats from FruitJuice from a year ago, my battery capacity reading was fluctuating between 85-90%. I’ll keep an eye on it.

It all boils down to: just use your device.

Many people (including the makers of FruitJuice) still apply Ni-Cad and lead-acid thinking to Li-ion batteries. Lithium ion batteries are different animals, so much so that

  • the people who invented the chemistry won the Nobel Prize in 2019
  • they are volatile enough that they are only made in an ~AA size
  • if a lot of cells are connected together, they can’t be shipped in passenger aircraft
  • Teslas use hundreds/thousands of these small cells to make up their battery packs.

The charging circuits and software are designed to optimize their life. If overcharging shortens the battery’s life, they don’t do that. If discharging to 0 shortens their life, they don’t do that.

Ni-Cads depended on the user to prolong their life. Li-ion don’t.

Just treat it like a phone. If you’re at your desk, plug it in. If you’re on the go, don’t.


I’m going to take this as “gospel” and go with it, because 1) I trust your expertise, 2) I prefer this approach, and 3) because of confirmation bias. :slight_smile:


Exactly. If it carries on running for another 5 years then I’ll be happy. If the battery is useless by then, I’ll get it replaced or throw the laptop away and buy a new one.

I have to say that FruitJuice’s estimations of charge and therefore useage time remaining is pretty accurate, which is why I use it.