Low battery on a MacBook: when should you plug in?

Plug in whenever it suits you, and try not to let the battery run all the way down very often. That is the whole answer for most people. The lithium-ion battery in a MacBook does not need to be emptied before it is charged, and topping it up halfway through the day does it no harm.

What matters more is avoiding the two things batteries dislike: regularly running flat, and getting hot. The rest of this post covers why, what macOS shows you as the charge drops, and how Low Power Mode can stretch the last part of a charge when there is no outlet nearby.

Plug in when it is convenient

Older rechargeable batteries, the nickel kind, could "remember" a shorter charge if they were topped up too often, so people learned to run them to empty first. MacBook batteries are lithium-ion, and they do not work that way. Short, frequent charges are fine.

It helps to know how Apple counts wear. A battery's life is measured in charge cycles, and one cycle is the whole capacity used up, however many charges that takes. Half the charge on Monday and half on Tuesday, with a top-up in between, make a single cycle. So plugging in early does not "waste" a cycle. You can see your Mac's cycle count in System Information, under Power.

A practical habit: when the battery gets to around 20 percent, start looking for a charger. That leaves time to finish what you are doing, save your work and find an outlet without rushing.

Why running it to empty doesn't help

Running a lithium-ion battery down to nothing on a regular basis puts it under more stress than keeping it somewhere in the middle. macOS protects the battery by putting the Mac to sleep before the cells are truly empty, but making a habit of reaching that point is still harder on it than plugging in earlier.

You may have heard that a MacBook battery needs a full drain now and then to "calibrate" it. Apple gives no such instruction for current MacBooks with built-in batteries, and doing it often only adds wear. There is more on this and other old advice in MacBook charging myths.

What macOS shows when the battery is low

The battery icon in the menu bar shows roughly how much charge is left. To see the exact number next to it, open the System Settings pane that controls the menu bar (Control Center in macOS Sonoma and Sequoia), find Battery, and turn on Show Percentage.

Click the battery icon for more detail. The menu shows the current charge and power source, and it lists any apps using significant energy. If one app is on that list and you don't need it right now, quitting it is the quickest way to stretch what is left.

When the charge gets low, macOS shows a low battery warning. If you carry on, the Mac eventually goes to sleep on its own to protect the battery and your work, and you will need to plug it in before it wakes. Open apps are usually still there when it does, but don't count on it: save anything important when you see the warning.

System Settings > Battery has a chart of your battery level over the last 24 hours or the last 10 days, which is useful if the battery seems to be draining faster than it used to. It also shows the level the battery was last charged to.

Low Power Mode on a Mac

Low Power Mode makes the Mac reduce its energy use to make the battery last longer. Apple's own description in the settings is that the Mac "will reduce energy usage to increase battery life and operate more quietly". Some tasks, such as exporting video or compiling large projects, can take longer while it is on. Everyday work like email, writing and browsing usually feels the same.

To turn it on:

1. Open System Settings > Battery.
2. Find Low Power Mode and choose when it should apply. On most MacBooks the choices are Never, Always, Only on Battery and Only on Power Adapter.

"Only on battery" is a sensible setting if you often work away from a desk. If you only want it in an emergency, leave it off and switch it on when the warning appears.

Other ways to stretch the last bit of charge

• Lower the display brightness. The screen is one of the biggest users of power.
• Quit apps you are not using, starting with anything on the significant energy list.
• Pause video and close browser tabs that are playing it.
• Unplug accessories that draw power from the Mac, such as drives you don't need right now.

Habits the battery likes

None of these need to be followed perfectly. They are general care for a lithium-ion battery, not strict rules.

• Top up when you can. Between meetings, at lunch, whenever there is an outlet nearby.
• Don't make running flat a routine. Once in a while is fine. Every day is not ideal.
• Keep it cool. Heat is one of the main things that ages a battery. Avoid charging on a bed or under a blanket where the vents and base can't shed heat, and a hot car is no place to leave one.
• Store it half charged. For a MacBook going into a drawer for months, Apple's advice is about half charged, rather than full or empty.
• Let macOS handle the top end. Optimized Battery Charging can learn your routine and hold the charge at 80 percent until you need it, which reduces wear from sitting full all day.

If the battery doesn't last as long as it used to, open System Settings > Battery and click the info button next to Battery Health. It shows how the battery's capacity compares with when it was new, and tells you if service is recommended. MacBook battery health explained goes through what those readings mean.

A nudge before the Mac goes dark

The trouble with low battery warnings is that they arrive when you are busy, and they look like every other notification. In Notchpals the battery belongs to the Tech care area, and the warning comes from the notch instead. When the charge drops below 20 percent and the Mac is not charging, Juice or Gumdrop, whichever is in your crew, peeks out to ask you to plug in. Juice, a battery who faints at the very idea, takes this one personally.

JuiceUnder twenty percent! I feel faint. Tell my story. And find a charger!

If the charge keeps falling and goes below 8 percent, it comes back with a more urgent visit. This one can even reach you during a focus session, when most of the crew stays out of the way.

JuiceSave your work, then save me! This is no rehearsal! Charger!

Plug in after a warning and it pops back once more, relieved, to celebrate the charger. Beyond that one cheer, it keeps quiet about the battery while the Mac is charging or already full, so there is no nagging when everything is fine. One honest limit: Notchpals never cuts into a call or a full screen app, and the battery warnings are no exception. If you are presenting or on a long video call on battery, watch the menu bar icon yourself.