MacBook Battery Drains Overnight With the Lid Closed

Close the lid at 90%, open it in the morning at 62%. Nothing was running. The Mac was, by every outward sign, asleep.

It was not, or not continuously. A MacBook with the lid shut loses somewhere between one and three percent across a normal night. Losing twenty means something woke it repeatedly, and macOS keeps a log of exactly what.

Know what normal looks like first

Before hunting a fault, check whether you have one.

Apple silicon Macs sleep far more deeply than Intel ones, which is why the expectation shifted. If you upgraded from an Intel machine and five percent feels normal to you, it was normal — on the old machine.

Read the wake log

This is the step that turns guesswork into an answer. Open Terminal (Applications → Utilities → Terminal) and run:

pmset -g log | grep -i "wake from"

You get a timestamped list of every wake, each tagged with the reason that triggered it. Common entries and what they mean:

• EC.LidOpen — you opened the lid. Expected.
• RTC — a scheduled timer, typically Power Nap or a background task.
• BT.OBEX or similar Bluetooth tags — an accessory sent traffic.
• USB or a device name — something attached asked for attention.
• EC.DarkWake — a maintenance wake with the screen off.

If the same reason appears thirty times between midnight and seven, you have found the cause without touching a setting.

For a shorter view of what is holding the machine awake right now:

pmset -g assertions

Anything listed under PreventUserIdleSystemSleep is actively blocking sleep, with the responsible process named.

The four causes worth checking

Power Nap

Power Nap lets the Mac wake briefly on battery to fetch mail, sync Notes and check Find My. The individual wakes are short. The cumulative cost over eight hours is not, particularly if your mail account is busy.

Find it under System Settings → Battery, in the options or advanced section depending on your macOS version. Turn it off for battery and leave it on for power adapter if you want it at all.

Wake for network access

A separate setting, and the more common culprit on a Mac that shares a printer or hosts anything on the network. It allows another device to wake yours by sending traffic to it. On a laptop, leave it off.

It lives beside Power Nap under System Settings → Battery, worded around waking for network access.

Bluetooth accessories

A mouse that gets nudged, a keyboard under a cat, a pair of earbuds in a bag that reconnects every few minutes. Each reconnection is a wake event, and the log will name Bluetooth if this is your problem.

Turn Bluetooth off before closing the lid for a night and compare. If that fixes it, the next step is finding which accessory, not living without Bluetooth.

Anything plugged in

A bus-powered external SSD draws power from the Mac continuously. A hub with devices hanging off it does the same. This is the single largest overnight loss on the table above, and it is not a fault — the Mac is doing what it was asked.

Unplug everything and test one night clean.

When the Mac is not asleep at all

macOS has two deeper problems that look like drain but are not sleep issues.

A process holding a sleep assertion. Media players, video conferencing apps, backup tools and some VPN clients ask macOS to stay awake and occasionally forget to release that request. pmset -g assertions names them directly. Quit the app, confirm the assertion disappears, and update or replace it.

Hibernation never happening. When a Mac’s battery runs low during sleep, it is meant to write memory to disk and power down. If the machine instead sits in a half-awake state burning power, you see large losses. This is far more common on Intel models and is one of the few cases where an SMC reset genuinely helps: shut down, hold Shift-Control-Option and the power button for ten seconds, then start up. Apple silicon Macs have no equivalent and do not need one.

Check the battery before blaming it

System Settings → Battery → Battery Health gives you condition and cycle count. Normal means what it says. Service Recommended means capacity has fallen far enough that Apple suggests replacement.

A worn battery shortens your working day. It does not cause a sleeping Mac to lose twenty percent, because a sleeping Mac is barely drawing anything from it. Treat overnight drain as a sleep problem first and a hardware problem last.

If the Mac also runs warm while apparently idle, the problem is a process, not sleep, and finding what is actually running on a Mac that gets hot covers how to identify it in Activity Monitor.

What does not help

• Battery calibration routines. Lithium-ion batteries in modern Macs do not need deep discharge cycles, and macOS tracks capacity itself.
• “Battery saver” utilities from the App Store. They cannot change what wakes the machine; the settings above can.
• Resetting NVRAM. It stores display, startup disk and volume settings. It has nothing to do with wake events.
• Shutting down instead of sleeping, as a permanent habit. It works, but it treats a symptom and costs you a minute every morning.

Realistic expectations

Turning off Power Nap and wake for network access, and unplugging accessories, takes a typical problem night from fifteen or twenty percent down to the normal two or three. The log tells you within one night whether you fixed it — rerun the pmset command and count the wakes.

One honest limit: a small number of Macs wake for reasons that resolve to vague tags like RTC with no responsible process named, and no setting stops them. If you have eliminated everything above and a handful of unexplained wakes remain, the practical answer is to shut the Mac down when you will not touch it for more than a day. That is unsatisfying, and it is still better than chasing a log entry Apple does not document.