When charging a phone wirelessly, there is sometimes significant heat generated. That combined with higher charging rates that are now coming out with the Qi 2 standard make me wonder what the ideal charge for the battery would be.
Most of the time I just toss my phone onto a wireless charger before bed, and don’t really care how quickly it charges. Would it be better to use a 5W brick with a charging pad? Should wireless be avoided and usb used instead?
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The very healthiest way? But maybe you won’t like it :)
Don’t charge above 80%, don’t discharge below 20%, charging current at 1/10 of the capacity, and always keep the thing at average room temperature.
Don’t charge above 80%, don’t discharge below 20%
This how I keep my phones healthy for 4-5 years at a time. I only this year upgraded my Pixel 4a 5G to a 7a, and only because Graphene EOLd the 4a.
My A52s has a built-in function to not let it charge above 80. I keep it on unless I need the extra 20% for instance when I’m away for a while.
Samsung Galaxy S24 has this too.
Really? My girlfriend’s A52 doesn’t have this feature. That is part of why I bought my Xperia 5ii. Is it a new feature?
(After 3 years the battery is at 70% on mine because apparently Sony uses shitty as hell batteries and software drain glitches, while my girlfriend’s A52 always charging to 100% lasts a day and a half with 3x the use, would not recommend)
Maybe it’s only in the A52s, not the A52.
I was actually thinking of using the battery charge limit feature to prevent charging above 90%. Not sure I could do 80 without an charge during the day, lol
Pragmatically speaking, for battery health you should charge only as much as you need the battery, so it sounds to me that in your case that’s 90%. Also, here’s a paper about battery charging:
Strategies to limit degradation and maximize Li-ion battery service lifetime - critical review and guidance for stakeholders https://deepblue.lib.umich.edu/bitstream/handle/2027.42/154859/Woody_Maxwell_Thesis.pdf
Given qi2 uses magnets to properly align the coils in the phone and the charger, it should result in generating less heat and overall greater efficiency, so it very well may generate less or the same amount of heat [edit: despite the higher amount of energy transmitted ]… That is, if your phone supports it. But all things considered, it’ll unlikely ever be as efficient, and, hence, warmer than a regular wired charger. I mean, you’re pretty much going ac → dc in the power supply, then dc → ac in the inductive charger, then again ac → dc in the phone itself for no particular reason. That being said, pd also runs quite hot at times, so, IMO, smth like plain old 5v 1amp charger would be more preferable given the use-case
Technically, wired charging degrades the battery less than wireless charging, mainly because of the excessive heat generated by the latter. The same way slower wired charging generates less heat. Lower and upper charging limits also help (the tighter the better).
But I personally don’t bother with it. In my experience, battery degradation and longevity mostly comes down to the “battery lottery”, comparable to the “silicon lottery” where some CPUs overclock/undervolt better than others. I’ve had phone batteries mostly charged with a slow wired charger degrade earlier and more compared to almost exclusively wireless charging others. No battery is an exact verbatim copy of another one. Heck, I had a 2 month old battery die on me after just ~20 cycles once. It happens.
Sure, on average you might get a bit more life out of your batteries, but in my opinion it’s not worth it.
The way I see it with charging limits is that sure, your battery might degrade 5% more over the span of 2 years when always charging it to 100% (all numbers here are just wild estimates and, again, depend on your individual battery). But when you limit charging to 80% for example, you get 20% less capacity from the get go. Unless of course you know exactly on what days you need 100% charge and plan your charging ahead of time that way.
Something I personally could never be bothered with. I want to use my device without having to think about it. If that means having to swap out the battery one year earlier, then so be it.
Additionally, if you follow the “stay between 20% and 80%” advice, you’re only ever getting 60% of your battery’s capacity.
Why not just use it normally and get 100% of it? And then sure, in 3-5 years the battery may have degraded down to only holding 60% of a charge, but that means you’re effectively in the same boat as above, except you got way more usability from the phone in the meantime, and you’ve not had to spend time stressing about your battery.
There’s also nothing stopping you from spending £30-60 and getting a new battery after 4-5 years.
It’s about usage patterns. If you know you only need 60% of the battery, charging it to 100% will degrade it more, for little utility. The newer Google phones get 7 years of updates, but without due care the battery will reach 80% of its capacity before that. On an aside, a battery is considered to have reached its end of life at a capacity reduction of 20%, and not 40%.
If you 100-0 the battery every day, then there’s not much you can do. But if you’re a lighter user, then using the 20-80% (or 40-60) part instead of the 40-100% part of the battery makes it last longer. And that’s good in terms of environmental sustainability, reduction of e-waste, and you can use the phone for longer, too.
The main thing (by far) degrading a battery is charging cycles. After 7 years with say 1,500 cycles most batteries will have degraded far beyond “80%” (which is always just an estimate from the electronics anyway). Yes, you can help it a bit by limiting charging rate, heat and limit the min/max %, but it’s not going to be a night and day difference. After 7 years with daily use, you’re going to want to swap the battery, if not for capacity reduction then for safety issues.
Because in 3-5 years I can just press a button and magically have 100% again when I need it. It’s not the same boat at all.
The real question is why would you deliberately accelerate the degradation when you don’t need it?
I already explained why you’d want to… So you get more use of your battery, and you’re not having to think about your battery constantly.
It’s virtually pointless to micromanage your phone battery like that.
Yeah I got lucky with my battery; it’s at 800 cycles currently and still holds plenty of charge for my daily use. A replacement kit is also only $50 so I figure there’s not much point in trying to be efficient for a marginal lifespan improvement. I’ll probably end up replacing it when it hits 1000.
Check ifixit before you buy a phone, to make sure diy battery replacement is not too difficult. Then you don’t have to worry as much. Just figure on a swap or two during the phone’s lifetime.
Other than that, keep charge level between 20% and 80% as someone said. But I think in that range, it’s ok to fast charge within reason.
Supposedly starting in 2027, all phones sold in EU will have user replaceable batteries.
Supposedly starting in 2027, all phones sold in EU will have user replaceable batteries.
Unfortunately, while the law is certainly an improvement, it’s not as good as the headlines have misled people to believe.
Anybody who thinks they’ll be popping the back off their phone and changing the battery like it’s 2006 will be disappointed.
The law stops the most egregious stuff (like glueing the battery down excessively in a way that requires specialised tooling to remove), but that’s about as far as it goes.
A confident tinkerer shouldn’t have an issue. But it’s a far cry from what many seem to think the law is.
There are also exceptions. If you guarantee the capacity being over X (I can’t remember what the law stipulates) after 3 years, the battery doesn’t have to be removable. And IIRC, it’s not a particularly ambitious amount. Like 74% or something.
I think everyone likes to glue down batteries now because that helps the phone’s drop protection. The adhesive strips aren’t so bad since you can heat them a little / use a spudger to get the battery out. It’s worse when they make it very hard to get to the battery, or make you unglue delicate parts like the screen. You are probably right to be pessimistic though.
I’ve found it remarkably difficult to replace a battery in a modern smartphone, even as someone who’s quite handy with electronics. Any improvement is greatly welcome, and I wish we’d do more to make it easier.
It’s definitely a welcome improvement!
I just don’t want people to get their hopes up too much thinking we’re in for a truly radical change across the industry
Trickle charging to 80 is going to help protect the battery for longer. Also, never charge it frozen.
Plenty of good answers here already. Just want to add a funny anecdote.
I’ve had the same USB charging brick for years, using it for different phones throughout that time. When I check the battery settings when it’s plugged in it “warns” me that I could be charging at a higher rate if I plug into a higher amperage charger. Yeah… I know. I WANT to charge slowly. It’s gonna be plugged in all night, what do I care?
I’ve had my phone for a year, 165 charging cycles, and it says it’s still at 100% health. I do cap charging to 80% and that hasn’t been an issue for my day-to-day usage.
Exactly this. Everyone focuses on how fast you can charge a phone, but 99% of the time I’m charging over night and would prefer a slower charge.
I just capped mine to 90%, if that goes well I might go down to 80.
Healthiest = slow charging via cable to 80% limit.
The further you stray from that the worst it is for your battery.
There might be even greater benefit limiting it to below 80, but not as significant as cutting the top end. The majority of battery damage happens at the last 10% of capacity and high heat.
Do you think trickle charging via wireless would be significantly worse?
The main issue with wireless is heat, at any charging speed it produces more heat than wired charging equivalent. With that said, if your room/charging spot is well ventilated and the ambient temperature isn’t too warm to begin with, it could be negligible.
My pixel 7 has adaptive charging. If there’s an alarm set and I charge it at night, it paces the charging to be full near the time I’m getting up.
So it’s doing what it can to preserve battery health.
Wish we could set the time ourselves, mine works sparaticly.
Going wireless will always add a layer of energy loss, in this case heat, during charging, no matter if it is properly aligned with magnets or not. So first step to reducing heat is to charge wired only.
Fast charging is also a way of generating more heat while charging, so limiting the charge speed is also a way to reduce that. If you’re going to charge your phone through the night, it’s probably a good idea to use a 5W brick to manually limit the charge speed. A quick way to enforce that is to use the USB-A port on the brick instead of the C port, that way the PD standard won’t be activated and will charge at a slower rate. (Though if your phone fast charges through USB-A like Quick Charge or SuperVOOC, it will not default to 5W. Use a cheapo brick or a computer USB-A port instead.)
Last would be to limit the charge level to 80%. Batteries are the most stable at half charge and stressed at both extremes, but that’s not practical for anyone to limit their devices between 40~60% charge, so 20~80% is a better compromise. iPhones now have the ability to limit their charge to 80% or 90% in iOS 18, so set that if you can. On Android, you’ll need to see if your phone and OS supports it.
Wireless charging always generates more heat than wired charging but it’s not always a significant amount.
Wired charging ports get dirty, wear out
Batteries last longer with slower charges.
Batteries last longer with less charges
Batteries last longer If they never leave a moderate temperature.
Batteries last longer if they never drop below 20% and never go above 80%
Batteries last longer when stored if they are stored at 50% charge.
Putting that all in check you can take a couple year old phone to a fix it place and have the battery replaced. And they can also replace your wired charging port if necessary.
The healthiest is to enable the option to only charge to 80% (or near there, depending on the phone you have).
Otherwise slower charging is better, if the wireless charging doesn’t make the phone hotter than say 30C or so I wouldn’t worry about using it. 45C is the limit for charging Li-ion safely, but it’s better to be cooler.
Bought a Xiamoi a few years ago, always wired charging. Almost never charge overnight, rarely let it go below 20%. I don’t to 80, i just let it reach 100%. It usually lasts me around 2 days.
It’ll decrease if i use the screen more (i’m not glued to my phone); it’ll significantly decrease if i check instagram too often.
