| HN Mirror

Yes and I felt Apple also wrongly got *flak about down-tuning some CPU performance settings when batteries start getting older. The same year that story went crazy, I had a Samsung Galaxy with a fairly used battery. Once it reached 25% capacity or so, it could still chug along fine for another several hours if you didn't do anything CPU-intensive. But drawing too much current from the battery (video/games/etc) would steeply drop the output voltage of the battery, and result in the phone instantly shutting off entirely. It was unlikely to successfully boot after that, because the boot sequence had a short stage that hit nearly 100% CPU utilization before power management kicked in.

Note that "25% capacity" is usually calculated from steady-state output voltage. The voltage of a battery generally drops slowly as it gets used. But when the battery gets older and its internal resistance increases, it can no longer output the same current at lower voltages. The energy is still there, but can only be accessed either by sipping it slowly for a long time at a useful voltage, or pulling the energy out quickly at a uselessly low voltage.

So two solutions could be: Let peoples phones randomly die sometimes at 20% charge. Or set 25% to "0%" and never let anyone use those extra few hours for idle texting/etc. Or throttle the CPU after the battery falls below 50% so the phone can't cause fatal battery voltage drops with short bursts of high CPU utilization.

I thought Apple made the right choice for consumers, it's the solution I would have wanted on my Samsung, and I was jealous iPhone users didn't have to deal with a phone that said "25% full" but could randomly shut off at any moment in your pocket or hand without warning.

*I believe it is flak, not flack.