Battery Drain Insights A MacBook that is closed and asleep should lose very little charge overnight. When it loses a lot, it was awake for part of the night. Either it kept waking for the network or for something connected to it, or an app held it awake behind the closed lid. macOS writes down which, and you can read it.
How do I know my Mac was awake while it was closed?
Open System Settings, click Battery, and choose Last 24 Hours. The Battery Level graph shows the charge for every 15 minutes of the day (Apple, View Battery Usage History on a Mac laptop). A line that stays flat through the night means the Mac slept. A line that slopes down while the lid was closed means it did not.
Two other signs point the same way: the Mac is warm when you open it in the morning, or the fan is running.
What wakes a sleeping Mac, or keeps it awake?
There are three usual reasons, and each leaves a different pattern.
| Reason | The pattern | Where to change it |
|---|---|---|
| Wake for network access | Many short wakes, a few minutes apart, all night | System Settings, Battery, Options |
| An app that holds the Mac awake | One long stretch awake, often hours | Quit that app before you close the lid |
| Something plugged in or paired | Wakes at odd moments | Disconnect it and compare a night |
Short wakes are normal in small numbers. A sleeping Mac wakes for a few seconds now and then, without lighting the screen, to check the network and keep Bluetooth devices connected. The trouble starts when those wakes come by the hundred, or when the Mac never goes back to sleep.
Apple describes the general case in If your Mac sleeps or wakes unexpectedly.
How do I see exactly what woke my Mac?
macOS keeps a power log of about the last two weeks. Reading it takes one command.
- Open Terminal. It is in Applications, Utilities.
- Type
pmset -g log | grep -E "Wake|Sleep"and press Return. - Find last night by the date at the start of each line.
The manual that comes with macOS describes this as “a history of sleeps, wakes, and other power management events”. Each line has the time, the kind of event, the reason after the words due to, whether the Mac was on battery, and the charge at that moment in brackets, like (Charge:71%).
What to look for:
- Lines with
DarkWake. A dark wake is a wake with the screen off. A handful in a night is normal. A long run of them is your answer. - The charge in brackets. Follow it down the lines and you see when in the night the charge went.
- The line
Dark Wake Count in this sleep cycle. It counts the dark wakes since the lid was closed.
A second command shows what is holding your Mac awake right now. Run it while the app you suspect is open:
pmset -g assertionsUnder Listed by owning process are the names of the programs that have asked macOS to stay awake, each with the kind of request, such as PreventUserIdleSystemSleep. Both commands only read. They change nothing on your Mac.
What should I change?
Start with the setting, because it takes ten seconds.
- Turn off Wake for network access on battery. In System Settings, Battery, Options, set it to Only on Power Adapter or to Never (Apple, Set sleep and wake settings for your Mac). In the pmset manual this setting is called
womp, described as the same as “Wake for network access” in System Settings. - Quit the apps that hold a Mac awake before you close the lid. Video calls, music and video players, backups, file sync and downloads are the usual ones.
- On an Intel MacBook, turn off Power Nap for battery. It is in the same place. Apple silicon MacBooks have no such switch.
- Disconnect drives, displays and hubs for one night and see whether the night gets quieter.
Then give it two or three nights. One quiet night can be luck.
How much charge should a MacBook lose overnight?
Apple publishes no figure, and it differs by model and by what is connected. The useful comparison is with your own Mac. If most nights cost a little and one night costs many times more, something kept it awake that night, and the power log has the reason.
Where Battery Drain Insights fits
Battery Drain Insights reads the same power log, with your one-time permission, and does the reading for you. Its History tab lists each stretch with the lid closed, the charge it cost, how long the Mac was really awake, and what woke it or kept it awake when that can be told. A night that cost more than your quiet nights is marked.
It cannot name a cause that macOS itself did not record. Some wakes are logged with a reason only an engineer could read, and the app says so instead of guessing.
For the other causes of fast drain, see the guide Why is my MacBook battery draining so fast?
Sources
- Apple, View Battery Usage History on a Mac laptop
- Apple, If your Mac sleeps or wakes unexpectedly
- Apple, Set sleep and wake settings for your Mac
- The pmset manual that comes with macOS. Type
man pmsetin Terminal to read it.