Thursday 19 October 2017


eXtensions - System Preferences in macOS High Sierra: Energy Saver

By Graham K. Rogers


In macOS, High Sierra (10.13), System Preferences has seen several changes, although some of the panels remain unchanged. The Energy Saver preferences panel has seen a couple of minor changes. It will differ slightly depending on whether it is for a desktop or notebook computer and depending on model specifications.

Different Energy Saver preferences panels are displayed depending on the type of computer being used. A desktop computer like the iMac or Mac mini will have a single pane, while a MacBook, with a battery, has a preference pane for each source: battery and power adapter. A feature called Power Nap has been available to users since version 10.10 of OS X when the preference pane was changed.

On earlier versions of OS X certain MacBook Pro computers had two graphics cards and there was a checkbox for "Automatic Graphics Switching". The same checkbox was in the Power Adapter pane. This allowed the computer to switch automatically between graphics modes for better battery life.

The display information and features differ with the selected power source and with the computer. All, however have the common feature of a single slider for "Turn display off after:" from 1 min to 3 hrs and Never.

Energy Saver
Energy Saver Preferences on MacBook (Battery)

When the battery is used, the MacBook Pro and the MacBook show three checkboxes (The 15" MacBook Pro also shows the checkbox above for graphics switching):

  • Put hard disks to sleep when possible
  • Slightly dim the display while on battery power
  • Enable Power Nap while on battery power

Energy Saver
Energy Saver Preferences on 15" MacBook Pro

If the power adapter is connected, the the MacBook Pro and the MacBook show four checkbox options:

  • Prevent computer from sleeping automatically when the display is off
  • Put hard disks to sleep when possible
  • Wake for Wi-Fi network access
  • Enable Power Nap while plugged into a power adapter (See below)

Energy Saver
Energy Saver Preferences on MacBook

The last option may not be available on older computers. In earlier versions of OS X, there was a further button marked, "Allow power button to put the computer to sleep." This is no longer available.

Beneath these checkboxes on both panels is information about the current state of the battery charge. To the right of this is a button, marked Restore Defaults. A desktop computer which has the single panel, will not have information about the battery.

For panels used on notebook computers, both the Battery and Power Adapter panels have a checkbox at the bottom left: "Show battery status in menu bar". When this is used a small battery icon appears on the menu bar with a display indicating the amount of charge remaining. When low, this changes to red. When dangerously low, a panel appears with a warning (a system voice may also make an announcement if alerts are activated in the Speech panel of Accessibility preferences).

Energy Saver A menu appears when the user clicks on the menubar icon. Items at the top of the menu are: either Time "Until Full" (adapter), or Calculating Time Remaining (battery) or a time figure; followed by "Power source" (battery or power adapter). The Current Battery charge will be displayed on the Energy Saver preference pane. If the panel is opened while the Option key is pressed, the condition of the battery will be shown at the top of the menu. This will change from Normal to indicate if the battery needs attention. Long periods with the power adapter attached may affect battery life.

When the menu is held open, it now shows "Using Significant Energy" (or No apps using significant energy). Applications or features (e.g. Display Brightness) using high levels of power are listed.

At the bottom of the menu are "Show percentage" (a figure is shown in the menubar) and "Open Energy Saver Preferences". When a power adapter is connected to the computer, menu items change and Time Until Full replaces Time Remaining (initially "Calculating time. . ." is shown). When the power is connected, the menu changes to show this source. Initially, it will show a Calculating time message, then the time until the battery is full.

If there is a problem with the power source, for example the connector is not fully inserted, the icon may show, Not Charging. Other system information may also appear, depending on the state of the battery.


At the bottom right of the panels is a button with the word Schedule on it. This reveals a panel in which it is possible to set times for start up or wake, or sleep. A checkbox turns on the action. These settings need Admin permission to change or activate (unlocking the padlock icon).

The top button allows for the computer to start up or wake: Every Day, Weekdays, or Weekends. Specific days of the week are also available. The specific time may also be set.

Energy Saver

A button below is for selection of an action: Sleep, Restart or Shutdown. Days and times can also be specified like in Wake or Start up. If the Startup checkbox is selected, a text appears below: "Scheduled start up will only occur when a power adapter is connected to your Mac." There is no text if the sleep box is checked.

Additional Information

The information here has been written using a MacBook Pro with Retina display, a MacBook and a Mac mini. Energy Saver preferences may differ depending on the specific computer being used. I will add a screenshot for the Mac mini in the near future.

A reader, Jon Austin, makes the valid point that - when playing online games - the checkbox for "Put hard disks to sleep when possible" should not be checked. He uses World of Warcraft as an example. To play this optimally, that box should remain unchecked, plus App Nap should be deselected for that application. The relevant folder should also be excluded from Spotlight searches. This sleep option may also affect other actions, such as online access.

See Also:

Graham K. Rogers teaches at the Faculty of Engineering, Mahidol University in Thailand. He wrote in the Bangkok Post, Database supplement on IT subjects. For the last seven years of Database he wrote a column on Apple and Macs. After 3 years writing a column in the Life supplement, he is now no longer associated with the Bangkok Post. He can be followed on Twitter (@extensions_th)



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All content copyright © G. K. Rogers 2017