MacBook Air shuts down at 20% battery power

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MacBook Air shuts down at 20% battery power

Since the last update, whenever my MacBook Air gets to 20% on battery power it shuts itself down without warning. When it comes back on, it usually shows that battery has completely drained to 0, although one time it came back on again at 20.

This has happened more than once. I have installed battery monitor app to see battery capacity.

After the 1st time, battery capacity was down to 75.

Then it went back up to 98 the next day.

Now after it shut itself down again today I am at 74% capacity.

The battery only has 38 cycles. I bought it last September.

I called Apple Support and after and hour they weren't able to see anything obvious.

Any thoughts anyone?

Thanks,

Laura

MacBook Air

Posted on Apr 26, 2020 11:35 AM

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Answer 1

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John Galt

Level 10

155,060 points

Apr 26, 2020 1:58 PM in response to Lauraw12

Now after it shut itself down again today I am at 74% capacity.

If that's correct, Apple should replace it under warranty.

Perform an SMC Reset: How to reset the SMC of your Mac. If that doesn't restore it to normal operation and capacity, contact Apple to get it fixed:

"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."

https://www.apple.com/batteries/service-and-recycling/

You do not need an app to check full charge capacity. I recommend using Apple's own System Information instead.

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Answer 2

John Galt

Level 10

155,060 points

Apr 26, 2020 2:15 PM in response to Lauraw12

Yes, but it's buried in ioreg. You can extract that information using Terminal:

ioreg -brc AppleSmartBattery | grep Design

... should return its design cycle count, maximum cycle count, and maximum charge capacity.

full / design = %

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Answer 3

Lauraw12 Author

Level 1

15 points

Apr 26, 2020 2:01 PM in response to John Galt

Thanks I’ll try the smc reset. And if no change I’ll call Apple again.

im using the app as I can

find current capacity in system info but not design capacity to compare it too. The app showed me that. Is the design info available in system somewhere?

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MacBook Air shuts down at 20% battery power

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