Macbook Air 2015 battery problem

Hello htlay,

Thank you for using Apple Support Communities. It's our understanding that your MacBook Air unexpectedly shuts down with 80% of battery remaining. We're happy to help.

If you haven't already, check the battery health in the System Preferences using the steps in the following resource: Get help with your Mac notebook battery

Do you see any error messages when the Mac shuts down? If so, take a look at the steps in the following resource: If your Mac restarted because of a problem

Let us know the results. Please include specific error messages and any other troubleshooting steps that you may have tried.

Have a nice day!

This is a 6 year old computer with a 6 year old battery. The Capacity may read as 83% but the sensors in the computer are reading this as Unreliable 83% and can not supply reasonable power to this computer. Thusly, shutdown to protect the components.

Batteries are considered Consumable Products. Over time it will degrade to a point where it needs to be replaced. The usage is normal as the capacity will go up and down all the time and never stay always at 100%. Apple Batteries are rated for 1000 Full Battery Cycles and / or 80% Capacity before needing Evaluation or replacement.

Find an Apple Authorized Service Provider

For additional reading on Battery and Apple Computers this link may help. About battery health management in Mac notebooks and especially for the M1 and Big Sur If battery charging is paused or on hold on your Mac

A feature introduced into Big Sur was to preserve the number of Full Battery Cycles - there was an Algorithm coded into the macOS. It is perfectly Normal for Big Sur to Pause / Suspend charging the battery beyond 80% and hold it at that level. One can nudge / over-ride this by clicking the Battery Icon on Desktop Top Bar and allow charging beyond 80%. From observations, it will Pause / Suspend again once reading 90%. Same procedure to over-ride and will charge to 100%

Have you tried running the Apple Diagnostics to see if they detect any hardware issues? It never hurts to try an SMC Reset either.

As P. Phillips points out just because the battery may appear to be healthy does not mean the battery does not have an internal hardware fault. I have encountered multiple batteries where the diagnostics report no problems and many times the battery will appear to work just fine, but once in a while I will notice something isn't quite right during my own testing. Sometimes a battery hardware fault can only be detected at a particular charge capacity which for you appears to be at around 80% or so. I have found that if the laptop is not working too hard that you may not even notice a problem, but if the laptop is working hard you may notice the battery drain very quickly at that point.

You should have Apple or an Apple Authorized Service Provider examine the laptop to provide you a repair estimate. Hopefully you can show them the failure since Apple typically doesn't replace "healthy" batteries until their capacity drops below 80% of design capacity.

htlay wrote:

The laptop is still good to use, except that I have to check for battery percentage so it will not shut down suddenly.

Sounds annoying. Probably time to have Apple or an AASP replace the battery. Better to have an original Apple battery while you can still get one replaced since the quality of third party Lithium-ion batteries is so poor.