Several users have reported an alarming drop in their MacBooks’ battery levels that appear to be related to a Bluetooth issue that was introduced in macOS 12.2.
Apple has recognized the issue and issued a fix in macOS Monterey 12.2.1 on 10 February 2022.
The macOS 12.2.1 fix also addresses a vulnerability in WebKit that would have made it possible to execute malicious code on the Mac, so you should install it now.
In the days before the release of the update Beta testers of the second developer beta of macOS 12.3 had reported that following the latest beta update, the problem had been fixed.
From what I can see, macOS Monterey 12.3 Beta 2 (21E5206e) fixes the Bluetooth battery drain issue. I tested 3 times & didn’t see a single DarkWake 👍 Test setup: 1. 2018 MBPro that had the issue on 12.3 B1 2. 12.3 Beta 2 and can’t reproduce the issue https://t.co/XVKe0oGYtW pic.twitter.com/23g6HuPPel
— Mr. Macintosh (@ClassicII_MrMac) February 8, 2022
What caused the macOS 12.2 battery issue?
The battery level of affected MacBook devices drops rapidly after a few hours in sleep mode. One user, in fact, says he saw his battery go from 100 all the way down to 0% during one night of sleep mode.
Whoa macOS 12.2 21D49 (the current version) is behaving like Windows! Battery went from full to 0% while on sleep mode overnight. Any fix, @AppleSupport? pic.twitter.com/w1kdJXyU7r
— fishjourner (@fishjourner) January 29, 2022
The one factor all the affected machines have in common is they have macOS 12.2 installed.
macOS 12.2 was released at the end of January 2022, and includes an updated Music app among other changes. But with software updates it’s often a case of two steps forward, one step back: changes bring new problems, which only come to light when a large number of users try out the update.
The problem reportedly lies in the fact that Bluetooth accessories can wake up the Mac even when it’s in sleep mode (as shown in the log files below). This is something that Terminal calls “DarkWake from Deep Idle”. The problem is said to affect both Intel-based and M1-based Macs, and seems reasonably widespread: users have complained of the issue on Reddit, Twitter and MacRumors’ forums.
@ Apple tweeps: macOS 12.2 breaks something related with bluetooth + sleep/wake. Looking at `pmset -g log`, it seems like it spent all night waking up every few seconds for bluetooth and drained all the battery. [FB9862509] https://t.co/5IF81PVw3P pic.twitter.com/qczeDKD5oX
— João Pavão (@jpavao) January 28, 2022
How to fix the Bluetooth battery drain issue
Users had managed to troubleshoot a (somewhat drastic) workaround for the issue: either turn off Bluetooth altogether, or turn off all connected Bluetooth accessories before leaving the Mac for the night.
Of course now that Apple has issued a fix in macOS 12.2.1 users should install that.
If you are looking for more advice about MacBook battery life read:
How to test a MacBook battery: see if it needs replacing & replace it
Author: Karen Haslam, Editor
Macworld editor since 2008, Karen has worked on both sides of the Apple divide, clocking up a number of years at Apple's PR agency prior to joining Macworld two decades ago.
Karen's career highlights include interviewing Apple's Steve Wozniak and discussing Steve Jobs’ legacy on the BBC. Her focus is Mac, but she lives and breathes Apple.