2017 MBA loses a third of battery charge sleeping overnight?

[flaubert]

Hi, I picked up a refurbished 2017 MacBook Air with the 2.2 GHz i7 processor last week. I've noticed something disconcerting: it loses roughly a third its battery charge overnight while sleeping! Yesterday the battery was at 84%, and today when I opened it the battery read 47%. That seems not right, especially considering I haven't even installed apps yet. Should I take it back to the store and ask for another one? Re-install the operating system? Typing this, it occurs to me that I haven't tried resetting the SMC yet; I'll have to try that next, but I would be curious what other steps you might suggest. It does seem to sip the battery juice properly while I'm actually using it; yesterday I was browsing the web for two hours, and the battery went from 100% down to 89%, which seems very appropriate.

How does one reset the SMC on a MacBook Air?

 

[flaubert]

Answering my own question on SMC reset:

Reset the SMC of your Mac - Apple Support

The SMC manages power and hardware behavior on your Mac. This troubleshooting article explains when you should reset it, what issues it can fix, and how to perform an SMC reset depending on your Mac model (Apple Silicon, Intel with T2 chip, or older Macs)

support.apple.com

Other information that may be relevant: I did update the computer to latest Mojave, and all supplemental updates. This process also brought the firmware up to date, as reported by Howard Oakley's utility, Silent Knight (which reports everything, including Gatekeeper and the Malware Removal Tool, is up to date. No Filevault encryption turned on yet.

As far as apps installed, very few: Thunderbird, Firefox, KeyPassX, Silent Knight and a few from the Mac App Store. Actually, reviewing those apps makes me wonder about a cool app that I installed right away on this machine that I've never run before, ArtPaper; it updates your background Desktop picture with a classic painting every day. Perhaps I'll have to try uninstalling that, and see whether it behaves properly. First I'll try the SMC reset, however.

 

[Audit13]

Sounds to me like an app or process is preventing the MacBook from entering sleep mode.

Did this MacBook come from Apple?

 

[flaubert]

Yes, picked it up at the Apple Store. When I select Sleep from the apple menu the screen goes dark immediately, so to all appearances it has gone to sleep. These newer laptops don't have the sleep status LED, so it's hard to be sure what state it has entered.

There aren't any processes that seem to be using a lot of CPU accumulated time, other than Safari. I might try putting it to sleep with Safari not running.

 

[flaubert]

OK, now I wonder if this is a user error situation... just now I closed the lid of the MBA, and expected that it would go to sleep. Then I opened the lid a minute or two later, the screen was fully lit and functional and it didn't ask for a password! So either all MacBook Air laptops don't automatically go to sleep when the lid is shut, or this MacBook Air doesn't go to sleep when the lid is shut.

I didn't notice the possibility that it didn't enter sleep earlier because the sequence was:

Close lid.
Put away overnight.
Open lid the next day.
Appeared to wake up because I was presented with a password request, but that could have been simply the laptop asking for a password after the display had gone to sleep.

Shouldn't closing the lid cause a 2017 MacBook Air to enter sleep mode?

 

[Audit13]

Were you prompted to go through the set up routine when it was powered on for the first time?

It may be set to never go to sleep.

Maybe wipe and re-install the OS?

 

[flaubert]

Yes, it came in a sealed box from Apple, did the usual set-up routine.

I ran a test overnight that seems to have confirmed my diagnosis: I charged up the battery to 100% and then manually selected Sleep from the apple menu before going to bed (and just left the lid open). This morning I woke it up and the battery had run down just a few percent to 96%, which seems pretty normal. That seems to say that selecting sleep manually works fine, but closing the lid and expecting it to sleep on its own has been shown not to work several times.

I think you're right, I'll have to try re-installing the OS from scratch and see if the behavior persists with only the base install.

 

[flaubert]

After going down a few dead ends and making wrong conclusions, it appears that the SMC reset has cured the battery run-down problem. It held charge at 100% overnight with just a lid close last night. Apple support's suggestion was an SMC reset as well, and when I told them I had done one just a day ago, they suggested just testing it overnight again with the lid close action.