iPhone 7/Plus Battery Degrading & Performance

[mikedis]

I’m interested in discussion on the iPhone’s battery degrading and how it affects performance.

As it stands now, my iPhone 7+ battery is at 75% Maximum Capacity. I’d like to learn a little more as to what exactly this means, and how it might be affecting my device’s performance. I’ve noticed slowed animations and general freezing over the past month or two, but I’m not exactly sure if it’s at fault of the battery. If anyone has some information to share, I would greatly appreciate it!

 

[C DM]

A similar type of recent discussion at https://forums.macrumors.com/threads/battery-count-at-84.2240967/ might be of some help.

 

[now i see it]

If a new battery has a capacity of 3000mAh (100%) it will have a capacity of approximately 2250mAh when it drops down to 75%. Basically the battery just becomes a smaller battery.
A 4000mAh battery at 50% capacity sort of equals a 2000mAh battery at 100% capacity.

But not quite—

When the battery ages, it can't discharge at as high of a current as it could when it was new - especially when cold. So a 75% capacity battery actually might be kinda unusable in cold weather but should be fine in warm weather but just not power the device as long as it did when it was new

 

[JPack]

As @now i see it mentioned, it's about the internal resistance of the battery, in addition to the reduced capacity. An aged battery has a higher internal resistance and cannot deliver high levels of current. The iPhone responds to this by throttling everything down.

In cold weather, internal resistance and capacity are further reduced. That's why you can expect to see unexpected shutdowns and even less capacity (fast draining) under those conditions.

 

[mikedis]

As @now i see it mentioned, it's about the internal resistance of the battery, in addition to the reduced capacity. An aged battery has a higher internal resistance and cannot deliver high levels of current. The iPhone responds to this by throttling everything down.

In cold weather, internal resistance and capacity are further reduced. That's why you can expect to see unexpected shutdowns and even less capacity (fast draining) under those conditions.

Pretty interesting. What’s weird is that my phone says it’s still working at peak performance, and I’ve never experienced a random shutdown.

 

[JPack]

Pretty interesting. What’s weird is that my phone says it’s still working at peak performance, and I’ve never experienced a random shutdown.

That is pretty interesting. Typically, Performance Management is enabled when the capacity drops to around 80%. If the Battery health is correct, then your performance issues are unrelated to the battery.

 

[rdy0329]

The shift from peak to degraded performance is not dependent on the battery % the software might have a monitoring system for unexpected shutdowns before it switches over to degraded performance Label and management.

 

[now i see it]

Yes-
The battery health app will show Peak Performance (un throttled) until there's an unexpected shutdown. Crashes almost always happen in the winter when the phone and battery is cold.
If there's just one crash due to low power, iOS will throttle the phone from then on until you reset that setting