4 ms·

I don't believe that the phone is slowing down to extend battery life. I believe it is because when batteries degrade, they can no longer supply the same max vo

I don't believe that the phone is slowing down to extend battery life. I believe it is because when batteries degrade, they can no longer supply the same max voltage they used to. This can lead to CPU instability, and CPU voltage requirements can be reduced by underclocking. It makes more sense to me since the race to sleep would be faster if the iPhone still had its higher max clock speed, which would actually save your battery more often than not.

guntars 9y ago
This is probably it. There is no way to tell the remaining charge of a lithium battery other than estimating it from the voltage which drops with the level of charge. It also drops more when it provides more power and this gets worse as the battery is aging (increasing internal resistance). This is why your phone might think that it has 20% battery remaining according to the voltage, but the second you open a power hungry app, the voltage drops below a safe level and the phone shuts down.