By Graham K. Rogers

In macOS, Sierra (10.12), System Preferences has seen several changes, although some of the panels remain unchanged. The Energy Saver preferences panel appears identical to before although it differs slightly depending on whether it is for a desktop or notebook computer.

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. I have been unable to check this with macOS, Sierra and for this description of Energy Saver, I am using a 13" MacBook Pro with Retina display (no graphics switching) and a Mac mini.

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.

Checkboxes are available for controlling how the computer works with the sleep feature, although not all are available on every device. On the Mac mini I use, the following are shown:

• Prevent computer from sleeping automatically when the display is off
• Put hard disks to sleep when possible
• Wake for network access
• Start up automatically after a power failure
• Enable Power Nap (a text below describes what Power Nap is)

Energy Saver Preferences on Mac mini

The last one 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.

In the Battery preferences pane, the MacBook Pro shows three checkbox options:

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

Energy Saver Preferences on 13" MacBook Pro (Battery)

When using the Power Adapter the MacBook Pro shows four checkbox options:

• Prevent computer from sleeping 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

Underneath these checkboxes on both panels is information about the current state of the battery charge and the estimated time until full. To the right of this is a button, marked Restore Defaults.

Energy Saver Preferences on 13" MacBook Pro (Power Adapter)

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 that indicates 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).

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.

Below this is a new section. When first opened, it will display "Collecting Power Usage Information". When the menu is held open, this changes to "Apps Using Significant Energy" and any such applications 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). If there is a problem with the power source, for example the Mag Safe connector is not fully inserted, the icon may show, Not Charging. Other system information may also appear, depending on the state of the battery.

Menubar display - Normal (left); and when Opened with Option key pressed

If the same 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.

Schedule

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.

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

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.

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