[jtbayly]

Wrong. The peak demand from the phone can exceed the available voltage even if you're at 30%, causing an immediate shutdown. That's what we saw a year ago. Now they no longer shut down unexpectedly, but the performance of the phone sucks, even with a battery that holds 87% of its original capacity.

[jlmorton]

I don't dispute that, but that does not explain the observations that a fully-charged, reduced-capacity battery performs poorly on a standard benchmark test versus a new battery.

It's not just smoothing out a peak demand. It's reducing the peak performance all of the time, and that is unique to iPhone.

[esmi]

You're assuming the issue is only changing capacity vs age. Internal impedance increases with age as well. A full battery that can't source its energy in a timely manner might as well be empty.

[unobtaniumstool]

That's not entirely accurate. They observed that with a fully charged battery it performed as expected. The CPU wasn't throttled until the battery was depleted.

[jtbayly]

That's not my experience. Unless depleted means 95% charged and 87% capacity compared to original spec.

Mine runs at 50% CPU speed under those circumstances. I wouldn't call that "performing as expected."

[ric2b]

> The peak demand from the phone can exceed the available voltage even if you're at 30%

So throw in a fat capacitor. This was a solved problem 50 years ago, the only problem is this constant rush to make phones 1% thinner.

I've never met anyone that used phone thinness as a metric when choosing a new phone and yet here we are.