(1/2) As a followup to my previous post, I decided to carry out some pseudo-controlled tests over the course of several nights to see if I could gain some insight into what’s causing the battery drain during sleep, primarily aimed at testing whether the ‘connected peripherals’ theory others have reported holds up. Here are my results:
Night 1 - Power adapter + external monitor connected via Apple VGA multiport adapter, but MacBook had ‘forgotten’* that power adapter was connected: battery drained 15% overnight while in sleep (from 86% to 71%).
Night 2 - Nothing connected to either USB-C port: battery drained 1% overnight while in sleep (from 39% to 38%), which seems reasonable.
Night 3 - ***Upgraded to Big Sur 11.2.3***; external monitor connected via Apple VGA multiport adapter (but not power adapter): battery drained 6% overnight while in sleep (from 100% to 94%). Interestingly, the battery did not drain steadily throughout the night, but remained fully charged from 10 PM until ~3 AM and then drained 6% by 7 AM when I woke it up. Evidently Big Sur 11.2.3 has not fixed the issue.
Night 4 - Only the Apple VGA multiport adapter connected (not the external monitor or power adapter): battery drained 9% overnight while in sleep (from 100% to 91%). This time the battery stayed fully charged from 10 PM till ~midnight and then lost the 9% between then and ~8 AM when I woke it up.
Night 5 - Nothing connected to either USB-C port: 0% battery drainage overnight.
Conclusion: Not exactly a scientific-grade sample size, but given that both nights that I left nothing at all connected to the USB-C ports resulted in virtually no battery drainage—whereas there was significant drainage the 3 other nights—it seems reasonable to conclude that there’s indeed an issue with leaving peripherals connected while the computer is sleeping. Even just the Apple VGA multiport adapter on its own, with nothing further connected to it, was associated with significant drainage during sleep.
It seems likely that this isn’t the only thing that causes drainage during sleep—I’ve read some other accounts (including in this thread) indicating that various background processes & software left ‘open’ during sleep could contribute as well. For the record, all of these nights I left a handful of native Apple apps (e.g. Mail, Messages, Safari with a whole bunch of tabs open, etc.) open upon putting the machine to sleep, though I deliberately avoided leaving any third-party apps like MS Office or Chrome open.
It might also be relevant to mention that I didn’t use the Migration Assistant to set up this new MacBook; I simply copied the docs I needed from my home folder on my old MacBook, exported/imported my archived emails, set up my active email & other online accounts from scratch, reinstalled the additional software I need from scratch, etc. So there’s zero superfluous ‘clutter’ accumulated over the years that could have carried over from my old MacBook’s System & Library folders, etc.
