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.

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.

Trickle charging to 80 is going to help protect the battery for longer. Also, never charge it frozen.

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.

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.

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.

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.

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.

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.