Battery: MacBook Air 11” 2015: MacBook Air 13” 2015: Size: 38 Wh lithium‑polymer battery: 54 Wh lithium‑polymer battery: Battery Life: Up to 9 hours of wireless web; Up to 10 hours of iTunes movie playback; Up to 30 days of standby time; Up to 12 hours wireless web; Up to 12 hours of iTunes movie playback; Up to 30 days standby time The M2 chip's efficiency is on full-display when it comes to battery life. On our test, the 15-inch MacBook Air lasted 14 hours and 48 minutes while streaming video, browsing websites, and running According to Apple, the M1 and both M2 MacBook Air models offer 18 hours battery life, while the 14-inch MacBook Pro offers an amazing 22 hours (the same as the 16-inch MacBook Pro). As well as the cycle count, this app shows us that the battery now has a Full Charge Capacity of 7098 mAh. When it was new, it had a capacity of 8755 mAh. Losing 15% capacity over almost three years isn't too bad at all. If you've got an older MacBook, the battery almost certainly holds less charge now than it did when it was new. My new Macbook Air(M1 Chip, Big Sur 11.1) uses a lot of the battery during sleep mode. As you can see screen usage is zero during night but buttery usage is hight. For example if my Macbook steel in sleep mode for two days then I can not start my Mac without connection to charger since battery goes to zero. Batteries are consumable components that chemically age over time. Factors like charge cycles and heat can degrade the battery, and leaving a Mac plugged in and charged to 100% constantly may XBte8s.