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Why Charging Your Gadgets Over 80% Is Such a Bad Idea | iFixit News
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this post was submitted on 16 Feb 2024
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Leaving a battery at 100% over a long time wasn't recommended but I would imagine most devices have BMS settings to deal with this now.
There's not much incentive to do that. Battery longevity reduces sales. Keeping the battery at 100% gives better review scores. It's a lose lose for phone makers to implement that.
All BMSs I've come across have this disabled by default sadly, manufacturers seem to target longest device runtime, rather than extended battery longevity
On my FP3 it needs to be enabled in a terminal, while rooted (newer devices have it in the settings).
On my Steam Deck it also needs to be enabled in a terminal, the exact command differs depending on the model of steam deck. An embedded developer or tinkerer will find it very quickly in the kernel sysfs though.
Edit: Apple and Lenovo are the only companies I'm aware of, who have historically cared for the internal batteries in certain models of their laptops. Macbook Pros in particular used to behave differently when they reach 90%, some will stop charging and others will wait a few hours then resume charging to 100% depending on how the machine is used. I assume this is the only reason why my 2012 MBP still is going great on its original battery, running Linux of course.
Lenovo used to let you configure the charge preferences in the BIOS of their ThinkPad line
This was a decade ago though, can't vouch for whether this applies to the modern stuff too
Laptop folks reading this - check your bios settings. My recent Dell (and I'm sure other brands are similar) has options for this. It has a "usually plugged in" setting, but I manually chose to limit charging to 80%, which is an option in the same place.
Obv if this is bad for your use case, don't do it.
My lenovo legion laptop lets me limit charging to 60% for maximum battery longevity
The chemistry from holding that last 20% of charge for a while is what causes the degradation. The BMS can tell the system to stop charging before it's full but it can't do anything itself to prevent the cell from slowly being degraded by full charging.
This is is a problem that occurs on the order of years and that's why the EV companies care but phones historically don't. More easily replaceable batteries is the real solution here, not software stopping you from fully charging.
It is not the "real solution". Increasing the battery longevity is much more sustainable than regularly replacing the battery, and is therefore the most rational and responsible course of action.
Yes, but to increase longevity energy density goes down substantially. Manufacturers (and many users including myself) would not make this decision for something as weight and size sensitive as a phone. The lithium ion batteries currently used already last for 2 years after all and are relatively small. A single model S battery contains 7104 individual cells for comparison. Further, lithium battery recycling has made substantial progress over the last year and will already need to be done at scale when higher volumes of EV batteries have reached their end of life. The impact of the of life phone batteries even from the entire world will be dwarfed by that of the 26 million EVs already on the roads today with thousands of cells each (or equivalent if using prismatic cells).
Some cars use LiFePO4 batteries for the superior longevity. But the range is reduced to somewhere between 1/2 and 2/3 their lithium ion counterparts. The industry is moving away from this trend in recent years in favor of traditional lithium ion with a software limited charge/discharge range.
I have a new laptop that was complaining that I'd had it plugged in too long. Apparently there's a battery management setting that will have it charge to 80% max. I've used laptops exclusively for like 15 years and this is the first one to complain about being plugged in constantly.
My (work) Dell laptop charges from the usb-c dock, which it's always plugged into because so are my monitors and ethernet etc. As a result, it's always on charge.