Mac battery guides

Every number in these pages is measured on real Macs, with the method and its limits stated. Where something can't be measured honestly, the page says so instead of estimating. Who measures this.

Battery health tells you how big the tank is. WattMate shows what is emptying it.

Where did my battery go?

The battery is draining fast. Which case is it? Four different problems share that one symptom, and only one of them is the battery. Each has a tell you can check in a minute. macOS says an app is "Using Significant Energy" The menu names the app and never a number, and Apple publishes no threshold. Why Activity Monitor shows nothing by the time you open it, measured. How many watts is my MacBook using? There is no single figure, and we can show why: 436 measured windows spanning 6.74 W to 59.73 W, and two Macs whose averages sat three times apart. Which apps drain a Mac's battery, measured in watts Chrome, Xcode, Telegram, Spotify and Slack on two Macs, side by side. The spread between the cheapest and the dearest turned out to be about four hundredfold. Does quitting apps actually save battery? Mostly no: macOS handles idle apps well. But when one app is the bulk of the use, quitting it is worth real minutes. How to tell which case you're in. Health says 96% but it only lasts four hours Health measures the size of the tank; runtime is capacity divided by the power going out. The watts-to-hours table, and the three cases where the battery really is at fault. The percentage sits still, then drops two at once Not a glitch: a whole number laid over a charge counter that moves both ways. 3100 measured steps, 218 of them backwards, and the largest hid 166 mAh. Battery health vs cycle count: which one matters? Cycles say how much life the pack has spent, health how much it holds now. One Mac at 538 of its 1000 rated cycles, capacity already at 82.22%. System Settings says 87%, my battery app says 85% The controller publishes two capacity figures (a smoothed one and a raw one) and software picks. Which is which, what each is good for, and why the number wanders during the day. Checking a used MacBook's battery before you buy A seller states a cycle count and a health percentage. Check the pair against 1,539 other real batteries at similar mileage instead of a made-up threshold. How much battery does Chrome actually use? 374 measured windows on two Macs: quitting it was worth 24 minutes on one and 142 on the other. Why the same app differs six-fold. Does Slack drain the battery? Measured twice, nine days apart: 0.01 W both times. The 7.4 W spike of the first run never came back. How much battery does Telegram use? A quarter of a watt as a matter of routine: about thirty times Slack, from a single process. Two runs agreed on every column. Does Spotify use much battery? No, by a wide margin: 0.03–0.19 W on two Macs. The app you notice and the app that costs you are rarely the same one. How much battery does Xcode use? 44 Wh, nearly three times Chrome on the same Mac. A peak of 48.5 W and 166 processes at once. Idle is cheap; builds are the entire bill.

Overnight and sleep

Why does my Mac lose battery in sleep? About a percentage point an hour is normal. Above that, something is waking it. And the arithmetic to tell one from the other. Who wakes your Mac at night? A study 88 wake-ups over six nights, every one silent, median 45 seconds. Then a second Mac that answered completely differently. Both sets of numbers, plus the counting mistake we found in our own method and corrected in the open.

Charging and power

The Mac stopped charging at 80%. Why? The charge controller records a reason code and macOS does not show it. One command reads it and names the cause instead of guessing from the percentage. Mac says "Charging On Hold" It's deliberate, not broken. Every status string decoded, how to charge to full now, and the one case no status string covers.

Updates

Battery worse after the macOS 27 update? The first days are partly expected while the system rebuilds its indexes. How to tell settling from an app that broke.

Choosing an app

The best Mac battery apps, sorted by the job Four different jobs wear the name "battery app". Honest picks for each, including the two where the answer isn't ours. Mac battery app alternatives: what actually changes All five comparisons in one place, including the two where the honest answer is to stay where you are. Every app reviewed on its own page What each product claims, quoted from its own site with the date checked, including where the other app is the better pick.

Head to head: WattMate and Juicy · WattMate and AlDente · WattMate and coconutBattery · WattMate and TurtleBar · WattMate and Endurance

Read the numbers yourself

Mac battery tools Three Terminal commands that print what macOS keeps to itself: both capacity figures your Mac stores, live power draw in watts, and the lifetime counters inside the battery controller. No password, nothing installed. What the app does, feature by feature Three measurements and the sentences the app uses when it cannot make them, quoted from its own strings.

How the measuring works

Why four fifths of your Mac's CPU energy has no owner The per-process energy counter dies with the process, and on an idle Mac that loses most of the work. Written for people building the same kind of tool. How we count The instruments, the arithmetic and every limitation we know about, including the numbers we refuse to print because they can't be measured honestly.