Apple MacBook Air 15-inch (M3) battery drains too quickly

The checks in more detail

A 15 inch Air has a bigger screen than the 13 inch, and the screen is the largest consumer, so brightness and True Tone, and the display's refresh settings, matter first. Apple's Activity Monitor shows energy use: open it, click Energy, and sort by Energy Impact to see which app uses the most, and the Average Energy Impact figure shows what has drained over the last eight hours. Browsers with many tabs, video calls, cloud sync clients and Spotlight indexing after an update are the usual culprits.

A Mac that has just been updated indexes for hours, and drains faster until done. MacUser's list of fixes adds practical items: close apps rather than leaving them running, turn off keyboard backlight when not needed, disconnect external devices that draw power, and keep the Mac cool, since heat reduces capacity. Battery settings in macOS include Low Power Mode, which reduces performance for longer life, and Optimized Battery Charging, which learns your routine and holds the charge at eighty percent until you need it;

if the Mac seems to stop at eighty percent, that is the feature working. A Mac plugged in all day stays at a limit. If the maximum capacity is under eighty percent after a short time, or the battery drains very fast at idle with nothing running, contact Apple, because the battery may be faulty and be covered by warranty. A swollen battery that lifts the trackpad needs immediate service.