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Comment by JamesTRexx | Hacker News Reader

After the first battery of my Samsung S4 expanded at the end of its life in less than 2 years, I found a utility that didn't work perfectly but could limit charge anywhere between 30 to 100% most of the time, and it prolonged the lifetime of the couple of later batteries during the 10+ years I used the phone with a limit around 66%.

I was glad to see my new Samsung XCover 7 has a built-in option to limit charge to 80%, although a flaky usb cable could sometimes overcharge to 100%. And also has a removable battery.

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It's probably not a flaky USB cable. Androids charging limit of 80% includes a policy to charge 100% every 14 days to recalibrate the battery controller.

A possibility to limit charging to ~65% does not exist per se but you can measure the time it takes to charge from 25% to 65% and use a power timer to shut down charging after that period of time. It's not accurate but easy to implement.

Another factor is fast charging... The battery loses capscity significantly faster if you fast charge often...

I personally only use the 80% limitation...

Maybe I just expect too much battery life, but I find that I get quite low or even run out when I limit charging to 80%.

My feeling is that the coulomb counting on the Pixel 8 Pro is just not very accurate, so the phone thinks it's at 80%, but is really at 60% or 40%.

I still use the feature, but now I have to top up during the day every so often. I suppose rationally I should just charge to 100% rather than take a medicine that causes the same side effect as the disease its meant to treat, but I'm not that rational.

Absolutely. I find it strange that Google decides to provide a fixed value of 80%. A slider from 65% to 95% would be more sufficient...

95% would probably work out for you and still decrease battery wearout...

> although a flaky usb cable could sometimes overcharge

The charge controller is in the phone. The cable and power supply have no bearing on when charging is terminated. Android has an "optimized charging" option where it will charge above 80% shortly before it predicts you are likely to unplug. Samsung may have meddled with this behavior but that isn't Android's fault.

You only charged your phone to 66% for ten years?

I definitely would do that if I could. I would absolutely love to tell it to only charge to 66% (or whatever, even 50% would work). I rarely use the phone for multiple hours at a time without access to power, and when I do, I usually know beforehand (like during a trip or something) so I could tell it to charge all the way. My battery rarely goes below 80%, even now that the phone is 3.5 years old.

I understand newer iphones now have the option to only charge up to a certain percentage. Mine doesn't have that, it only has the "smart charging", which tries not to charge it too quickly and only is full by the time it expects you'll use it (usually in the morning). It's very hit and miss for my use patterns, so it ends up at 100% most of the time...

Veeeeery slow charger :)

But yeah, at some point we should also consider the tradeoff between convenience and battery life. Batteries can be replaced, having to charge twice a day is a PITA for me.

My charging solution is that I've purchased three (cheap and therefore slow) wireless charging docks that sit my phone slightly leaning backwards, therefore nicely viewable if necessary.

One sits on my desk at work, one sits on my desk at home and the third sits on my bedside table (it acts like a clock radio / alarm clock). I just place it on the relevant charger while working / sleeping and it's always got enough charge when I need it.

(I also use the surprisingly fairly recent addition of charging protection to limit it to 80% charge)

I'm aware this won't work for all use cases, but it's great for mine.

Those really make my phone overheat, so I avoid them. Didn't they heat yours up?

Sometimes the phone is warm, I wouldn't even say hot. Could be because I bought lower wattage wireless chargers - I don't need it to charge fast, I just need it to top up the battery.

The only time my phone has given me a message about heat was, indeed, in a phone holder in the car, but it wasn't even charging. We are experiencing a heat wave in Australia right now though, and the car had been sitting in the sun in a car park for an hour.

They’re a joke, I used to have one in my car and the combination of sunlight & internally produced heat would make my phone shut off & display a “iPhone is too hot” message. Even when it’s cold outside.

I think that's just sun+charging, not wireless charging specific.

I switched to wired charging with the phone mounted in the same spot and the heat issue went away. Wireless charging produces a lot more heat than wired.

That's really quite interesting. I know the wireless charging uses more power to deliver less power, so there's heat generation due to the loss of power in the transfer (I'm assuming that's how it works).

But, I figured that the battery would heat up more the faster it's being charged, and so wired charging at the same wattage would heat the battery more than wireless charging.

Must be a lot of power->heat transfer loss with wireless charging.

Time for a new Vapor Cooled iphone?!

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