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MacBook Air (13-inch, 2017) Processor 1.8 GHz Intel Core i5 Memory 8 GB 1600 MHz DDR3 Graphics intel HD Graphics 6000 1536 MB It’s been shutting down unexpectedly. At first, it was every 1 hour or so, than minutes, so on and so forth. I’ve tried an SMC reboot, NVRAM, reinstalling macos. I did a hardware check (holding d on the keyboard when powering on). They said it could be the power adapter so i changed it, only for it to say that no issues were detected. Battery condition, it says normal and with a cycle count of 731. What could be the issue? Could the battery be faulty regardless of what the mac says? Thanks.

Yep, it’s a bad battery here. Here is parts and guide on how to replace battery. Guide is the same for 2013-2017 13” airs. MacBook Air 13" Early 2015 Battery Replacement MacBook Air 13" (Late 2010-2017) Battery