Battery Monitor gives a clearer view of MacBook power use

Battery Monitor was previously called Battery Diag. There was a review of the app on this site that was posted in May 2014. This is an updated version. The photo shows the 2014 version of the app. It has barely changed its look in the past 11 years and most of the changes since 2014 are either bug fixes or necessary updates to keep up with operating system changes. Here's an updated look at the software.

Still useful in the age of all-day batteries

Ironically, because the modern Apple MacBook Air has a longer battery life than earlier laptops, there’s a greater need to know how much juice is still in the tank.

That may not make sense at first until you realise that in the old days you were always at the point where there was no much power left. You were never that many minutes away from needing a top-up.

When the original version of this review was posted in 2014, a MacBook Air battery gave about ten hours of use. That was a huge leap, previously you might have managed four or five hours. Today, a M4 MacBook Air can go all day on a single charge.

With so many hours of computing from a single charge, it’s easier to lose track of how much is left.

Compact and lightweight

Battery Monitor from the Mac App Store is free and visually attractive. It has a design that echoes earlier versions of the iOS design found on iPads, iPhones and, surprisingly, Westpac bank's web site in the years around 2014. That said, it still looks modern and not remotely out of place on a 2025 MacBook.

The app runs in the menu bar, so you can get at it quickly, it sips resources and stays out-of-the-way until needed.

Having Battery Monitor and the MacOS Battery icon on the menu bar at the same time is odd. You can turn the official Apple icon off from System Settings.

Readouts and reporting

Click on the menu bar icon to get a report on the amount of power left both as a percentage and as a time estimate. There’s also an indicator showing the state of battery health and number of charge cycles. Further information, including battery temperature and power usage is hidden behind an I icon.

The time remaining estimate can be misleading. The number is based on your recent use and current environmental conditions. If you change what you are doing, the actual amount of time left can change significantly. Think of it as a suggestion, not a hard and fast limit.

The clever bit is that if you’re running out of juice, you can tinker with your open apps and usage to trim the power drain and extend the time remaining.

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