azurelunatic | Weekend!

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Weekend!

Throat is the sort of sore which could be a result of sleep and not drinking enough water, or could be a sign that I have The Housemates' Cold (I was sneezing a bit last night, and I just heard Belovedest coughing in the living room).

I was grumpily intending to remain in bed all day, dammit, because my knees were not good this past week, but I will probably at least get up for food.

When I got the battery on this here phone replaced, the tech talked sternly about properly charging and discharging for maximum life. I... have a lifestyle that doesn't match my battery size, so if I leave it discharging all day, I'm on the train when it starts going low. At which point my options for charging are fewer, and are mostly slow. I don't want to get stranded with a dead battery. So I may start blithely ignoring the best practices again, with the understanding that I will probably have to replace the battery again in a year or so.

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What are the best practices? I tend to kill a charging port before I kill a battery, so I've never really paid attention to the latter.

I've heard from various sources that optimal battery life is between 40% and 80%. Apparently running the battery fully charged or letting it drain all the way are both bad, so running it mostly 'in the middle' extends the life of the battery.

There are a *lot* of myths out there about battery management. Many of them do not apply to modern li-ion batteries.

I'm not an expert, but so far as I can make out the following three things are true:

* Being at 100% charge, or being charged the last few percent to 100%, reduces battery life. This is why some laptops have a "only charge to 50%" option, for use when they're mostly being moved between plugged-in locations. It's why it isn't great for phones to stay continually plugged-in and topped-up - but if you need your phone to always have a full charge available, then there isn't much alternative to this.

* Discharging to a very low level can damage, or kill, a battery. But this isn't a level that any phone will let you reach through usage. This is more along the lines of "running the phone until it shuts down and then leaving it sitting in a drawer uncharged for another 6 months". If you do that, it probably won't work again. But in more normal usage, using your phone to when it automatically shuts down isn't gonna hurt anything. Nor is it going to benefit anything either, with one caveat:

* It is beneficial to occasionally run a battery from full down to the level at which the device shuts down without plugging it in in between. This is not for reasons of battery chemistry, but for reasons of allowing the battery's firmware - and probably also the phone's OS - to recalibrate what voltage it should show as (eg) 10%. This value changes over time, as a battery ages and wears, so the phone needs to see the full range of charge levels from time to time to keep up.

For phone use, at least for me, this all mostly translates to "just use the thing". I tend to buy cheap phones, and I find that I'm usually replacing them after around 18-30 months for other reasons before the battery becomes too much of a problem.

ETA: I should also note that fast chargers do reduce battery life. This is because the fast charging tends to heat things up, and heat - especially heat when charging - is bad for batteries. On the other hand, fast chargers are very convenient, and the effect probably isn't a very big one.

Edited 2018-12-09 01:58 (UTC)

Discharging to a very low level can damage, or kill, a battery. But this isn't a level that any phone will let you reach through usage. This is more along the lines of "running the phone until it shuts down and then leaving it sitting in a drawer uncharged for another 6 months".

That makes a lot of sense.

It is beneficial to occasionally run a battery from full down to the level at which the device shuts down without plugging it in in between.

INTERESTING. I usually panic if I ever get down that low because I thought it was a horrible thing. I think after tonight's charge-up, I'll let it do that!

Some extra points:

Fully (i.e., unsafely) discharging a Li-ion battery will not only reduce its capacity, but there's a chance it might explode when you charge it up. Any battery in a consumer device should have protection circuits that stop you from running it down to unsafe levels through use, but a li-ion battery left at 0% for a long time should probably be considered dangerous.

Any consumer device will have protection against over charging, but if someone decides to cowboy up a 'fast charge' involving a car battery, run away. There's lots of videos on YouTube about exploding batteries, because it's easy to recreate and looks dramatic. The first few seconds of this one should get the point across: https://www.youtube.com/watch?v=YuKF8XfCVKQ

Apple used to have a really good web page on this stuff, but it looks like it's been replaced with more iPhone/Apple-device-specific bits: https://www.apple.com/batteries/