This is the story behind the MacBook battery monitor.
About
What is MacBookBatteryMonitor and why does it exist?
macOS tells you your battery percentage. It does not tell you which app just cost you twenty minutes of charge, or that your battery has degraded to 84% of its original capacity, or that Chrome has been pulling 8 watts for the last hour. We built MacBookBatteryMonitor to make that stuff obvious.
The problem
MacBooks have great batteries. Apple Silicon machines in particular can last a full workday on a charge, if you are using it right. But when you really use your device your battery can drain incredibly quickly, macOS gives you almost no way to figure out why or if this is normal.
You can open Activity Monitor, switch to the Energy tab, and sort by Energy Impact — a vague number with no unit that does nothing to really tell whats going on. You can open System Settings and see your battery percentage and a small undetailed graph showing you nothing useful. You can check your battery health, again in a small subsection of System Settings. None of it is connected, real time, understandable. None of it lives in a place you can check without going out of your way and by the time you think to check you have already blasted though 50% of you battery.
The result is that people live with faster drain than necessary because they do not know which app is causing it, and they replace batteries earlier than they need to because they are going through many more battery cycles as a result. Often its not the app you have open thats chewing through your battery but something random in the background that you forgot about.
What MacBookBatteryMonitor does
MacBookBatteryMonitor is a native Mac app that lives in your menu bar, it gives you:
- Live power draw in watts — the actual wattage your Mac is consuming right now, updated in real time. If it spikes, you can see at a glance.
- Per-app power usage — a list of every app drawing power, sorted by impact, with a quit button next to each one. You can see that Chrome is pulling 6 watts and kill it without switching windows.
- Battery health details — maximum capacity percentage, cycle count, and condition. No digging through System Settings.
- Energy history— charts that show your power draw and battery level over time. Spot patterns like “every afternoon at 3pm my power spikes because Slack starts syncing.”
- One-click Low Power Mode — toggle it from the menu bar instead of hunting through settings.
It is a native Swift app designed to launch quickly, keep its interface responsive, and stay out of the way until you need it.
Why native matters
Per-app power tracking has to sample process activity frequently enough to catch short spikes without making the monitor itself a meaningful source of drain. Building the app in Swift gives us direct access to the macOS process and power APIs while keeping that sampling work tightly controlled.
MacBookBatteryMonitor is built with Swift and AppKit. You can choose sampling intervals from 1 to 30 seconds, trading faster updates for lower monitoring overhead. A privileged helper enforces features such as charge limits and per-app controls; the interface and sampling work remain native to macOS.
If you are trying to figure out why your battery is draining, the last thing you need is another app making it worse. Native was the only honest choice.
Why it exists
I built this because I was frustrated. My 14-inch MacBook Pro would last about 2 hours on a charge instead of the 10 Apple advertised! I knew something was wrong, but I could not figure out what. Activity Monitor showed me a number called “Energy Impact” with no unit. I wanted to know watts. I wanted to know what percentage my battery health was actually at. I wanted to see my drain over time so I could figure out the pattern.
None of that existed in a single place. So I built it.
Once I built it I really understood why my battery was only lasting 2 hours, screen brightness maxed out was pulling 15W of power alone let alone the other apps I had left in the background sitting there 'idling'. I genuinely didn't realise how much power an idle app could use, especially because it turned out to be specific apps rather than every app.
What the current app includes
The current release combines live per-app watts, CPU/GPU/RAM/display/USB power context, battery-health history, configurable charge limits, Sailing Mode, Low Power Mode automation, and controls for runaway apps. Current licensing and compatibility details always live on the product page so this article cannot drift when the offer changes.
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