User level: Level 1 (4 points)M4 MacBook Air battery health dropped to 98% after macOS 27
I have a M4 MacBook Air with 43 cycles.
Before updating to macOS 27, my battery health was 100%. A few days after the update it dropped to 99%, stayed there for about 5 days, and today it suddenly dropped to 98%.
Has anyone else had this happen after updating to macOS 27?
Could it just be the battery health being recalculated, or should I be worried?
Posted on Sep 22, 2026 4:19 PM
User level: Level 10 (85,896 points)Sep 22, 2026 5:16 PM in response to jimmyspaschali
Welcome!
Health is notoriously inaccurate, based on an inaccurate baseline value.
It also varies. A lot. I saw swings of over nine Health points on an older Intel MacBook Pro I still have. After 13 years of hard use, its battery is still above 80% health and delivers very usable runtimes between recharging.
My M4 Pro Macbook Pro's battery "health" did not change whe I updated to Golden Gate, so it is not a universal condition.
I've been in these forums a dreadfully long time and, historically, people reporting here who have the best service from their batteries are those who do not obsess over unstable, inexact Health values.
User level: Level 7 (21,895 points)Sep 23, 2026 5:02 AM in response to jimmyspaschali
Just make sure battery charging optimization is turned on in settings and use the MacBook Air as you normally would. If line power is available when you are using your Mac, plug it into the charger.
Batteries are consumable items and when you no longer have useful working time when on battery and it is below 80% capacity, replace it.
User level: Level 1 (4 points)Sep 23, 2026 5:33 AM in response to Allan Jones
Thank you for the explanation. This is my first MacBook, so I wasn’t sure how accurate the battery health was. I was just a bit worried because it suddenly dropped to 98%, but I’m really happy with the Mac so far. It’s been great.
User level: Level 1 (4 points)Sep 23, 2026 5:37 AM in response to woodmeister50
Thank you for the tips. I already have charging optimization on. Appreciate the help.
Originally posted at discussions.apple.com/thread/256363056