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Understanding batteries in Mac notebooks

MacBook, MacBook Air, and MacBook Pro computers come with lithium polymer batteries to provide maximum battery life in a compact space. To understand battery technology and battery life, it's good to know common battery terminology:

  • Cycle count: Batteries are expected to function for a certain number of cycles. This number represents the sum of total and partial discharge cycles throughout the life of the battery. You can see the cycle count limit for your computer by reviewing Determining battery cycle count for Mac notebooks.
     
  • Full charge capacity: Measured in mAH (milliampere-hours), this refers to the amount of power the battery is capable of containing, less the energy required to shut down the device. This number lowers as the battery becomes depleted with usage and age.
     
  • Remaining charge capacity: This number represents the current amount of power left in the battery as measured in mAh (milliampere-hours). Using the computer when not connected to AC power will cause this number to lower as power is depleted from the battery.
     
  • Consumed / depleted: Consumable parts are those that deplete over time as their internal components are used. Batteries, due to their chemical components, are considered consumables, and over time they lose their ability to hold a charge. If the cycle count on a battery exceeds its expected limit, the battery is considered consumed.
     
  • Defective: Batteries are considered defective when they stop working due to a defect in materials or workmanship, or due to a manufacturing defect. Defective batteries are covered under Apple's one-year limited warranty and extended-service contracts.
     
  • Load: The amount of activity being performed by a task or tasks. Certain power-intensive processes place a heavier load on the battery and result in a much-reduced runtime per charge.

Setting up your Mac for the first time

When you set up your Mac for the first time, some activities—like setting up Mail and Photos, downloading your files from iCloud, and indexing your files with Spotlight—can use more power than your Mac requires in general use. 

If you have a large amount of data to transfer over Wi-Fi, it might take a few days for your Mac to finish its setup process. It's best to keep your computer connected to a power source during this time. Once setup is complete, the battery life will begin to reflect the regular activities you perform on your Mac.

The battery status menu

Your primary resource for viewing battery status is the battery status menu. It shows you how much charge your battery has and whether it's currently charging. This menu is at the right side of the menu bar:

battery status menu

The battery status menu also tells you if your display or any apps are using significant energy. Click Display Brightness if it's listed under Using Significant Energy, and your display dims to 75% brightness. Also consider closing any apps that are listed to save battery power.

To see the health of your battery, hold the Option key and click the battery icon in the menu bar to reveal the battery status menu. You'll see one of the following status indicators:

  • Normal: The battery is functioning normally. 
     
  • Replace Soon: The battery is functioning normally but holds less charge than it did when it was new. You should monitor the health of the battery by checking the battery status menu periodically.
     
  • Replace Now: The battery is functioning normally but holds significantly less charge than it did when it was new. You can safely continue using your computer, but if its lowered charging capacity is affecting your experience, you should take it to an Apple Store or Apple-authorized service provider.
     
  • Service Battery: The battery isn’t functioning normally. You can safely use your Mac when it's connected to an appropriate power adapter, but you should take it to an Apple Store or Apple-authorized service provider as soon as possible.

While some third-party apps report on battery health conditions, the data reported by these apps may be inaccurate and isn't a conclusive indication of actual diminished system run time. It's best to rely on the information reported in the battery health menu, described above.  

Optimizing battery life

Your notebook battery life depends on your computer's configuration and how you're using the computer. Here are some settings and steps you can take to get the most from of your MacBook, MacBook Air, or MacBook Pro battery.

Energy Saver in System Preferences

The Energy Saver pane in System Preferences has options to help improve the battery life on your Mac notebook when it's idle. For instance, setting your display to sleep when idle temporarily turns off the backlight and significantly improves the battery life.

Deselecting "Enable Power Nap while on battery power" can also extend your battery's charge.

On 2016 MacBook Pro computers, the display brightness adjusts to 75% when you unplug the computer from power if you have "Slightly dim the display while on battery power" enabled.

Energy saver window

The example above is from OS X Mountain Lion v10.8.4. Some features such as Automatic graphic switching and PowerNap aren't available on all Mac notebooks or versions of macOS.

Adjust keyboard and display brightness

Your Mac notebook's built-in keyboard has settings that can help automatically conserve battery power:

  • Choose Apple menu > System Preferences, and then select Keyboard. Enable "Adjust keyboard brightness in low light" to allow your keyboard's backlight to automatically dim or brighten. 
  • In the Keyboard section of System Preferences, you can also allow your keyboard's backlight to turn off after a period of inactivity.

You can also use the F5 and F6 keys to manually adjust your keyboard's brightness, setting it as low as possible while still allowing you to see the keys. 

Your display's brightness has a major effect on battery life, and allowing your display to automatically adjust can significantly help to conserve power. Choose Apple menu > System Preferences, and then select Displays. Enable "Automatically adjust brightness" to allow your display to dim or brighten based on your surrounding's light levels.

You can use the battery status menu to quickly reduce your display brightness to 75%. From the battery status menu, choose Display Brightness in the Using Significant Energy section.

To manually adjust your display's brightness to a comfortable level, use the F1 and F2 keys.

MacBook Pro with Touch Bar

If you're using a new MacBook Pro, you can quickly adjust your display brightness by tapping  in the Control Strip on the right side of the Touch Bar. To access the keyboard brightness buttons, tap  in the Control Strip:

The Control Strip expands, and you can tap     to adjust your display's brightness, and tap     to adjust keyboard brightness:

Graphics performance and its impact on battery life

MacBook Pro 15-inch and 17-inch notebooks commonly include two graphics processors, or GPUs. You might see them documented as a discrete GPU and an integrated GPU.

The discrete GPU generally provides substantial performance at the expense of high power draw. The integrated GPU allows for optimal battery life, but in most cases doesn't have the performance of a discrete GPU.

For optimal battery life, use the integrated GPU. These articles provide steps for using these different GPUs and information on what might drive unexpected use of the discrete GPU:

Disabling features and technologies that use power

Mac notebooks have a number of integrated technologies which can have a significant effect on battery power.

  • If you don't need Wi-Fi or Bluetooth, you can disable AirPort or Bluetooth from their menu bar icons or in System Preferences. This will help save power.
  • External USB, FireWire, Thunderbolt, SD card, and Expresscard devices added to your notebook can also draw power and should be disconnected for optimal battery performance.
  • Eject any CDs or DVDs from the integrated SuperDrive (if your notebook has one) to avoid the drive spinning periodically.