Why Charging Your Gadgets over 80% Is Such a Bad Idea | Hacker News Reader

Why Charging Your Gadgets over 80% Is Such a Bad Idea

ifixit.com

12 pointsmrzool10 comments

Batteries are not expensive. If the battery was easily replaceable and the phone could detect a defective battery (perhaps a sensor to detect the start of swelling?) then eeking the most life possible out of the battery would be something few people would care about. They'd just replace the battery. Extending the usable life of a battery seems like a reaction to the reprehensible practice of not making batteries easily replaceable. Yet another business practice (like elaborate packaging) that wastes energy, time, and resources.

Maybe to you. At $150 per kWh, I'd call them expensive. Especially if they only last 2-3 years.

I just had an under-warranty 1500 watt battery replaced in my mower.

Batteries are expensive.

Article doesn't mention some common issues:

a) If battery already has significantly reduced capacity, every % of charge is charge that may be needed by user. Battery going empty just when device is needed, is often worse than battery capacity approaching "useless" even faster (especially if battery is replaceable). And even with near-dead battery: power banks are a thing.

b) Article says up to 4x longer lifetime if battery is never charged above 80%. But it describes that as "more juice delivered to device over battery's life".

Yes: charge-discharge cycles are 'cheaper' in the lower-to-middle of a battery's voltage range. But that's not the same as "will live 4x longer". Modern Li-ions will simply degrade over time, even if you're not using them. Degrading will just go faster if battery is (ab)used regularly.

c) Many devices don't have an option to limit charge to a set %. Doing this manually doesn't work too well.

All recent Samsung devices (or at least the smartphones and laptops I've seen) have a setting to stop charging when the battery is 85% charged.

I think there are Android apps that can do the same on other brand phones. Wonder if anyone can recommend one.

Battery Life Extender - https://play.google.com/store/apps/details?id=com.fruit4droi...

I believed this had been "fixed" by masking the underlying physical layer-1 concept of 100% by a higher layer abstraction which SAID 100% when what it meant was "this is as much juice as I am willing to put in"

That’s interesting, do you have any source?

No. I just believed (wrongly) the chips on the cells said 100 and 0 at the set points which avoided killing the chemistry.

Oh I see, I misread :)

Disclaimer: I'm not an expert, so take this with a grain of salt.

There's always going to be some trade-off between how full you charge the battery and how much it degrades, so of course manufacturers choose a threshold that isn't going to destroy the battery too quickly.

The problem is that this isn't exposed to the user (e.g., there's no way to temporarily override it to a higher threshold when you actually need it). This means the threshold needs to be set quite high (to avoid wasting usable capacity), and manufacturers don't have much incentive to make the battery last more than a couple of years.

Limiting to 80% in software is a way around this, because users (and reviewers) can use the full "100%" (still an arbitrary threshold) when they need it, and choose for themselves how long they want the battery to last.

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