The Samsung phone I use these days has a "Protect Battery" mode that can be toggled (both manually and with automatic user-defined routines). It limits maximum charge to 85%. For those who want it: That's the ~same thing, without the psychological trick.

It also has some other settings that relate to smart charging that I don't fully understand (mostly because it's kind of inscrutable).

But the idea, AFAICT, is that it works with a person who charges their phone on a fairly regular schedule (they sleep at about the same time every night with plugged in all night).

The battery meanders up to 85% or something and holds there. Shortly before the person normally wakes up, it starts coming the rest of the way up to 100%. And then they wake up, unplug the phone, and it begins to discharge.

This helps to minimize the duration of being at a high state-of-charge, which is also a big factor in long-term battery longevity.

It's a tidy set of tradeoffs, I think.

Nice idea. I think the reason it's not communicated as such is that then companies would be expected to advertise time on battery when charged to 100%, not 125%.

Yes and yes.

I recently investigated large portable power banks (Jackery, etc.) and like that there are options to charge faster with a battery life tradeoff. Let people make their own informed choices.

It has been on iPhones for quite some while, but on androids even longer. Before that it was in the form of some smart charging scheme that it would only finish charging until the moment it thought you would unplug it.

It makes a bit of a difference, but not dramatically: https://youtu.be/kLS5Cg_yNdM?t=3m26

In that experiment, it’s also unclear if the 30% lower limit or the 80% upper limit is more important. I suspect the former.

I charge my s25 to 80%. Previous phone (pixel) was also limited to 80%, but radio stopped working after 2 years so I had to buy a new phone.

As do iPhones. I expect all flagship phones these days have the same ability.

On Pixels too.