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I just bought a new MacBook Pro 2015 15" and I really want the battery to stay healthy.

Is there a way to force my Mac to use the Power adapter as power source, instead of using the battery as source and charging it at the same time? (The Mac already does this when the battery is at 100% to, well, have the battery stay healthy.)

  • Thanks but these are from 5 years ago! – LinusGeffarth Apr 7 '17 at 8:16
  • Try apple.com/batteries then :-) – nohillside Apr 7 '17 at 8:19
  • I checked that already, but it it doesn't answer my question, which is why I asked. Also, why is it "too broad"? I want to know exactly one thing: how can I force my Mac to use the power adapter instead of charging the battery? – LinusGeffarth Apr 7 '17 at 8:22
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    The questions linked by @patrix in the first comment are still valid after 5 years because physics hasn't changed since then. However, if you need something more recent, see this answer If you bought a MBP to stay plugged in all day and you're worried about the battery, you should have bought an iMac. – Allan Apr 7 '17 at 9:34
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I still don't understand your question.

You want to plug it in but not charge the battery? Why?

My vague understanding about batteries speaking with hardware repair shops, etc. is that it's no longer truly worth worrying about. You charge when you can, you use the battery when you must. While plugged in, the battery charges until full and then stops charging. Presumably, at that point, it's using the power cord and not the battery.

The other thing that I seem to recall is that it's all about the charge cycles. You want to keep that number down. So, if you work from home one day, it would be better to leave it plugged in all day because that would only be one cycle (assuming you plugged it in first thing in the morning). If you plugged it in until it was charged, then unplugged it and used it until it was low on battery, then repeated, that would be 2, 3, or 4 charges during the day depending on how you use the computer.

So, what I've heard from people much more knowledgeable than I, is that the potential gains you might experience doing "the right thing" are not worth the effort required to realize those gains.

  • As far as I know, lithium-polymer batteries stay healthy the longest, when fully discharged before being fully charged. If that's true, I'd rather not charge the battery from like 30%. That's why. – LinusGeffarth Apr 7 '17 at 9:19
  • Again, I'm no expert, but I've been in this business for over 30 years. My understanding is that what you are describing applied to the Nickel-Cadmium (Ni-Ca) batteries that powered laptops 15-20 years ago. And users were cautioned to unplug the cable once charging reached 100% because otherwise, they might over-charge. But, for 10-15 years, that's no longer the case. I don't think that full discharge is needed or even recommended. – Zonker.in.Geneva Apr 7 '17 at 9:36
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    In any case, download the free app CoconutBattery. It will tell you your current battery health. It will tell you original and current capacities. You can take periodic snapshots. It's a good utility to have. – Zonker.in.Geneva Apr 7 '17 at 9:38
  • I just found this. TL;DR, but it's chock full of information. batteryuniversity.com/learn/article/… – Zonker.in.Geneva Apr 7 '17 at 9:40
  • Cool. I think this sentence answers my question: "A partial discharge reduces stress and prolongs battery life, so does a partial charge." – LinusGeffarth Apr 7 '17 at 9:42

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