An uninterruptible power supply (UPS for short) can provide continuous power to your devices in the event of a power outage. They can also amplify power sages (brownouts) and condition power in areas with poorly managed power grids. UPSs have been around for decades, and Apple started providing silent, built-in support in macOS many years ago. It is currently found in System Preferences > Energy saver on Macs that need to be connected, such as an iMac or Mac mini. (This goes to System settings > Energy saver in macOS 13 Ventura.)
At one level, a UPS is only as good as its integration with the equipment it helps maintain. A modern, high-capacity UPS can provide all the power needed to keep your Mac and peripherals running during brief outages that can range from a few minutes to tens of minutes. But for failures of unknown duration, you want to define parameters for an orderly shutdown. While system corruption was common when hard drives took over and before changes to macOS that improved recovery, they’re still not unheard of for sudden power losses.
Every UPS model I tested for TechHive has a USB connection or compatible port. All also offer downloadable software for macOS and Windows. However, the software is often outdated, difficult to use or too detailed. In most cases, you don’t need to make any changes to the low-level settings; if you do, it may be easier to use the settings on the front panel of the UPS.
By simply connecting one of these devices to your Mac via USB, macOS can recognize their status: it can see when the UPS is in a mode where it is supplying power and read the percentage of power remaining. Support is surprisingly widespread. Once connected, a UPS button will appear in the Power Saver pane. Click it to access some settings and a nested dialog box with more.
You can set how long the display should remain active after the UPS switches to backup power directly from the tab. Modern displays are low-wattage, but you may prefer to turn off the display earlier to keep your system running for longer. If you find that your UPS starts to run regularly, you can enable the “Show UPS status in menu bar” option to see a special power icon. Click it to see the current charge of the UPS battery and other details identical to viewing the battery status on an Apple laptop.
Click Shutdown Options and you can selectively enable and set three parameters that determine when shutdown occurs:
After using the UPS battery for: Set a duration for how long you want your Mac to run on battery power.
When the time remaining on the UPS battery: This is an estimate that macOS generates by looking at the drop in level while the UPS is supplying power. If you have an idea of how long it will take for our Mac to shut down, you can use that as a guideline.
When the UPS battery level is lower: Expressed as a percentage, you can use this in addition to or instead of the time remaining estimate.
Calculate the total power of your Mac and all other connected devices and use UPS maker tools to determine how much time you can run on backup power. macOS running on an SSD usually shuts down quickly – my M1 Mac mini shuts down in less than 20 seconds in most cases – you can time your own device shutdown if you’re worried it could take more than a minute.
You can fine-tune the shutdown settings with that data to give yourself (or software working on tasks) the longest available time before being forced to go offline.
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