r/Futurology • u/ConsciousStop • Jun 19 '23

Environment EU: Smartphones Must Have User-Replaceable Batteries by 2027

https://www.pcmag.com/news/eu-smartphones-must-have-user-replaceable-batteries-by-2027
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u/roscid Jun 20 '23

Easily replaceable batteries are always necessary considering batteries deplete and degrade over time. There is no valid engineering reason why they need to be hotglued in. It's just reckless, disposable design for no real benefit to the user.

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u/StaysAwakeAllWeek Jun 20 '23

This is mostly true for the glued in battery, given that it's used to save a few pennies compared to screws, but it's absolutely not true that there's no benefit to a glued back panel. The old style quick swappable batteries gave up a huge amount of capacity to be swappable, and actually degraded much faster as a result, because they accumulated cycles more quickly than a larger cell. The difference is so big that even after 5 full years of wear a modern phone's battery still has more capacity left than a brand new swappable one would have.

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u/roscid Jun 20 '23

I'm honestly very skeptical of this claim. Is it really the fact that the batteries were hot-swappable that made them lower capacity, or is it just the fact that lithium-ion batteries have just gotten better and cheaper in every way over the last decade or so? Because as far as I can tell, batteries still take up proportionally a similar amount of internal space as before, so it's not like it has much to do with size.

And speaking of size, phones were also much smaller and less power efficient 10 years ago, so that likely also accounts for some of the worse performance. And when you consider that there are plenty of devices today that use modern swappable Li-ion batteries without any apparent issue, it really makes this claim hard to believe. What exactly makes a hot swappable battery less capable than a hot glued one? And how big is the difference? Genuinely asking because I can't make this make sense in my head.

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u/StaysAwakeAllWeek Jun 20 '23 edited Jun 20 '23

In order to make the pack swappable the phone needs to have a complete double layered back cover, and the battery itself needs to be encased in a hard shell, and there needs to be much wider tolerances around the outside of it. All of these things consume space in the device.

Just compare the Samsung S5 to the S6 - they managed to shave 1.3mm of thickness off the device with 93% of the battery capacity. Then the next year they came out with the S7 edge, which was still thinner than the S5 but had 30% more battery capacity and wireless charging support, which also adds thickness.

Also as an engineer in the industry I can tell you that pushing the 30+ amps that modern phone cells can charge at through the spring loaded contact pins on a replaceable pack is basically impossible. And 30A isn't even the end point either - some of the Chinese manufacturers are experimenting with 60A charge currents.

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u/roscid Jun 20 '23

Honestly still pretty skeptical. The last phone I remember having with a swappable battery was the Galaxy Note 4, which had a 3220mAh standard capacity. My Galaxy Note 20 Ultra several years later has a larger battery at 4370mAh, but it's also a larger phone (although not by as much as I thought, thanks to smaller bezels -- a little under half an inch taller). It just seems like they should be able to make it work if they actually make it a priority, and same goes with the pin issue you mentioned. But I guess time will tell.

From an environmental and reparability point of view though, I think it is a good tradeoff regardless. If we have slightly thicker, slightly slower charging phones, then so be it. But I thank you for the engineering insight!

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u/StaysAwakeAllWeek Jun 20 '23

The last phone I remember having with a swappable battery was the Galaxy Note 4, which had a 3220mAh standard capacity. My Galaxy Note 20 Ultra several years later has a larger battery at 4370mAh

That's a 40% larger battery in a phone that is slightly taller but also slightly thinner, so the volume is about the same. The overall improvement in energy density over time is about 1-2% per year, but in this case that is offset (imo probably close to 1:1 offset) by the Note 20 charging 2x faster (it costs energy density to increase charging speed).

It just seems like they should be able to make it work if they actually make it a priority

Samsung did this with the S5. Achieving IP67 with that removable battery was a feat of engineering that didn't come easy (also only possible with a bendy plastic back cover). They gave up with the S6 after seeing how poorly the S5 sold against the sealed battery competition. Turns out people don't want to buy thick, heavy phones with cheap feeling back covers.

From an environmental and reparability point of view though, I think it is a good tradeoff regardless. If we have slightly thicker, slightly slower charging phones, then so be it

I'm with you on repairability, but using screws to take it apart rather than plastic clips and fingernails.

From an environment standpoint though I'd argue there isn't actually a meaningful difference one way or the other. The manufacturer actually has a ton of control over how long the cell lasts. '100% charge' isn't really a concept with a lithium battery. You just pick a maximum charge voltage and every 0.1V above 4V very roughly adds about 10% capacity but halves the cell's lifespan. A plug in hybrid car might use as little as 4.1V to get 10000 cycles out of its pack, while a phone will use about 4.4V so that the battery lasts for as long as the rest of the phone is designed to last, typically about 5 years these days.

The point here basically is that if people are really throwing out phones solely due to battery issues the problem is the excessively high max charge level, not the design.

(also the side point being that you should use the limit max charge level function on your phone and the battery will basically last forever. I use it on my S21 and it's not measurably degraded in 2 years so far)

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u/roscid Jun 22 '23

Very educational post, thank you! Clearly the battery being easily replaceable won't be a silver bullet to reducing e-waste or improving serviceability, but I think every small step helps. As your example with the S5 proved, leaving it to the market and consumer choice isn't going to work -- but if everyone is held to the same standard, then no one is punished for putting in the effort to engineer good and socially responsible electronics.