Simon ([personal profile] swaldman) wrote in [personal profile] azurelunatic 2018-12-09 01:54 am (UTC)

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.

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