At what % does battery health become an issue

[Galacticos]

My iPhone battery is at 92% health. I don’t think it’s performing too badly - that is, it usually goes down or up with software updates more than I would notice the missing 8%..

But is there a ‘critical’ % that after which it’s all downhill.

This is obviously general chit chat, not a ‘serious’ phone problem

 

[enmanuelrrr]

Below 80%, you should consider replacing your battery.

 

[C DM]

My iPhone battery is at 92% health. I don’t think it’s performing too badly - that is, it usually goes down or up with software updates more than I would notice the missing 8%..

But is there a ‘critical’ % that after which it’s all downhill.

This is obviously general chit chat, not a ‘serious’ phone problem

You would likely start noticing at least somewhat worse battery life below 90% and when it's closer to 80% or below it'll be in at least somewhat unreliable area with even worse life that replacing it would be a really good idea.

 

[MrGuder]

My 6s is on the original battery and I'm at 77% health. This past weekend I had 65% battery used google maps in the car for about 15 mins and when I got to my destination I had 35% and when I went to use safari my phone shutdown with the plug in to ac icon. I turned it back on and it started then shutdown again. When I got back to me car plugged it in and it read 30% battery which was a lie because it just shut down. I plan to get the free battery replacement from Apple soon, will print this out when I arrive. My serial # matches so it will be free like this bulletin says not $29.99

https://www.apple.com/support/iphone6s-unexpectedshutdown/

 

[JPack]

It really depends on the individual battery.

I would begin to pay attention at 90% and monitor very closely at 85%.

Battery capacity is only one measure. Another measure is battery impedance and as your battery ages, it can no longer deliver the required current. Your battery might be able to maintain run time for low power apps, but sudden spikes like loading the camera or GPS can cause the phone to shut down.