iPhone 17 Pro Max Overnight charging 5W or 20W?

[BigMcGuire]

There is no reason to use the 5W brick these days....I tried one out on my 15PM for a bit and it yellowed and nearly melted from how scorching hot it got trying to charge the phone. Meanwhile the 20W does it without breaking a sweat and the phone barely gets any warmer than it would with the 5W. I carried on using the 20W for something like a year and a half on the original battery charging only via the 20W and my USB port in my truck, and the phone continued to have 100% battery capacity for something like 330 cycles. There is absolutely no evidence to support charging via 5W helps anything long term, and as such there really is no logical reason to limit yourself to 4-6 hour charge times with the tiny cube anymore, especially when doing so gets it as hot as it does.

Thank you. I had this experience with two separate 5watt Apple chargers. All this time thought it was just me.

Those things got BURNING hot - to the point where both yellowed visibly (wish I had taken pictures). I put one on a Kill-A-Watt and it outputs more than 5w - and I think that's where the problem lies.

Those with 5w adapters - after an hour - should test the heat output of those things - mine were BURNING hot. That's not efficient or sustainable long term.

 

[msackey]

OP, I would just use a charger that came with one of your old phones with adapter or USB A to USB C cable.

My husband keeps pestering me about getting rid of those 5W chargers from Apple. I got rid of some of them but kept maybe like 4 or 5. They are not only so cute, but they are compact! I also thought, well, maybe they are good enough to charge things like Airpods, so I could have one charger in my office just for that.

I wish power bricks were smaller these days.

 

[uacd]

Is it better to have lower heat over a prolonged period? or higher heat over a shorter period? have no idea just asking. maybe 5W charger with a fan is the
best?

Interesting question I think low heat over longer period is better for battery health, and 5W is unbeatable in this because it generates minimum heat during charging. Higher heat is OK but still not as good as low heat. As for fan, I've seen few Samsung wireless models that use fan during wireless charging, and you can control power with slower bricks, so you get best of both worlds: wireless charging+safe, slow charging

 

[stikle]

Just use the charger that come with your phone…

They don't come with chargers anymore...so great suggestion.

 

[geta]

They don't come with chargers anymore...so great suggestion.

Read post #79…

 

[Radeon85]

25W MagSafe only for me. My 16 PM after a year of wireless only charging, no ridiculous battery limit or optimised charging, was still at 100% after a year. With my older MagSafe, my 15 PM was at 99%, 14 PM 100%, can't remember what my 13 PM and earlier phones were, but they've never dropped under 97% after a year and I've been charging wirlesley only since Apple first supported it.

Just charge your phone and enjoy it; no need to worry about this battery degradation crap.

 

[ignatius345]

I'm not one to go nuts figuring out how to micromanage my battery, but I'm using an old Nomad Base qi charger that I really like. It's super heavy, first-gen qi but with magnetic alignment. It charges very slowly, but the alignment thing is excellent and it's heavy enough to stay put when I pick up the phone. The slowness (5W? 7W?) is a liability for quick top-offs during the day, but it's perfect at night when I've got (ideally) 8 hours to charge.

 

[ignatius345]

why so many of you charge at night while sleeping?
what if a charger overheats

Because it's the ideal time to charge your phone. I've been doing it since my iPhone 4S (and whatever cell phones I had before that, plus iPods, PowerBooks, MacBooks, headphones, e-readers and god knows what other devices) and it's all been absolutely fine.

Not saying nothing could ever go wrong, but I think the real dangers come from things like cheap or damaged extension cords, maybe buried under carpets and the like. A decent quality charger and cable is going to fall way down the list of electrical fire hazards.

 

[ArchEtech]

I had issues with battery health on the 15pro. It lost over 10% in a year. No such issue with the 16pro max. 99% with heavy use and plugged in all night every night, charging to 💯 with optimized on. I would assume the 17 won’t have the issues of some past phone degradation but no way to know until next year when we are all bitching about the 18’s!

 

[teh_hunterer]

I had issues with battery health on the 15pro. It lost over 10% in a year. No such issue with the 16pro max. 99% with heavy use and plugged in all night every night, charging to 💯 with optimized on. I would assume the 17 won’t have the issues of some past phone degradation but no way to know until next year when we are all bitching about the 18’s!

It's luck of the draw with the battery that ends up in your specific device, not something to do with the whole 15 Pro model.

Sometimes your particular device gets a great battery, sometimes it doesn't.

 

[ArchEtech]

It's luck of the draw with the battery that ends up in your specific device, not something to do with the whole 15 Pro model.

Sometimes your particular device gets a great battery, sometimes it doesn't.

There were tons of complaints about the 15's with this issue. Its also related to the device. Maybe its better or worse depending on the luck of the draw, but no way thats the only factor.

 

[FeliApple]

I think that battery health doesn’t matter to determine battery life. That said, I exclusively charge with a 5w charger just because it simply isn’t inconvenient.

I don’t need fast charging, so I just charge with the 5w. I’ve had to use my 20w charger exactly once with my 16 Plus. I needed to charge relatively quickly, the 16 Plus was at 50%, and I didn’t have the 3+ hours required. So I used the 20w for the first and only time.

Whether I charge overnight or not, I use the 5w, but especially for overnight charging. No drawbacks at all.

 

[newellj]

I used to use the 5W chargers on the theory that less heat during charging was better. The trade-off is that 5W charging is not heat-free, and the battery is exposed to that heat for much longer. I gave up and went to max-rate USB charging and I don't think it's affected the health of the various phones I've owned, although I never did a side-by-side scientific test.

There are other ways to approach this issue. For example, more frequent but shorter charges.

 

[1rottenapple]

Just use the charger that come with your phone…

I see what you did there. I took me a second haha

 

[FeliApple]

I used to use the 5W chargers on the theory that less heat during charging was better. The trade-off is that 5W charging is not heat-free, and the battery is exposed to that heat for much longer. I gave up and went to max-rate USB charging and I don't think it's affected the health of the various phones I've owned, although I never did a side-by-side scientific test.

There are other ways to approach this issue. For example, more frequent but shorter charges.

Apple’s addition of health and cycles to iOS devices has massively increased the amount of available data points.

Even though I don’t care enough to try to grab all of the numbers I see and run some sort of study on them, the general eye test agrees:

The variation is so massive that it doesn’t matter EXCEPT for overwhelming heat. Most of the results that mention devices being in schorching heat for long periods of time have a pretty poor ratio. Now, this might also be because only those who have poor results mention the heat, but it would go in line with science.

Going back to the topic, if you avoid heat, I don’t really think that there is a repeatable difference between 5w and 20w.

That said, however, I’ll keep charging with the 5w since it presents no inconvenience to me.

But pretty much the only way to kill an iOS device’s battery life isn’t the battery degradation itself: it’s updates. Five, six, seven major updates and the device just can’t cope anymore regardless of health.

So for me the answer really is, if you are going to upgrade frequently, do whatever you want. If you are going to keep the device for years, maybe avoid heat and wireless charging. Then charge in the most convenient way.

Do you charge overnight, once? Maybe the 5w is fine. Do you need faster charging? Then charge faster.

The point of view that is tougher to understand in my opinion is everyone who doesn’t keep devices, who upgrades every year, and for some reason still cares.


Battery limits, slow charging, etc. Why? You won’t kill a battery in a year, why care at all? You can do whatever you like of course, it’s just pointless.

Or alternatively, those who keep devices for years caring about health and limiting their available battery life and charging slowly when it is a massive inconvenience only to update through anything and everything and kill battery life regardless. You jeopardised your own usage (because you are inconveniencing yourself) only to kill battery life anyway.

That said… as to the thread topic: if the 5w charger gets unbearably hot as @BigMcGuire said, avoid it. Otherwise I’d just use that one. The device will be charged by the time you wake up anyway.

 

[snipr125]

I used to use the 5W chargers on the theory that less heat during charging was better. The trade-off is that 5W charging is not heat-free, and the battery is exposed to that heat for much longer. I gave up and went to max-rate USB charging and I don't think it's affected the health of the various phones I've owned, although I never did a side-by-side scientific test.

There are other ways to approach this issue. For example, more frequent but shorter charges.

Apples 12W charger that came with the iPad Air 3 is a good sweet spot in terms of heat/charging speed. Also a GaN 20W charger will be similar.

 

[BigMcGuire]

Apple’s addition of health and cycles to iOS devices has massively increased the amount of available data points.

Even though I don’t care enough to try to grab all of the numbers I see and run some sort of study on them, the general eye test agrees:

The variation is so massive that it doesn’t matter EXCEPT for overwhelming heat. Most of the results that mention devices being in schorching heat for long periods of time have a pretty poor ratio. Now, this might also be because only those who have poor results mention the heat, but it would go in line with science.

Going back to the topic, if you avoid heat, I don’t really think that there is a repeatable difference between 5w and 20w.

That said, however, I’ll keep charging with the 5w since it presents no inconvenience to me.

But pretty much the only way to kill an iOS device’s battery life isn’t the battery degradation itself: it’s updates. Five, six, seven major updates and the device just can’t cope anymore regardless of health.

So for me the answer really is, if you are going to upgrade frequently, do whatever you want. If you are going to keep the device for years, maybe avoid heat and wireless charging. Then charge in the most convenient way.

Do you charge overnight, once? Maybe the 5w is fine. Do you need faster charging? Then charge faster.

The point of view that is tougher to understand in my opinion is everyone who doesn’t keep devices, who upgrades every year, and for some reason still cares.


Battery limits, slow charging, etc. Why? You won’t kill a battery in a year, why care at all? You can do whatever you like of course, it’s just pointless.

Or alternatively, those who keep devices for years caring about health and limiting their available battery life and charging slowly when it is a massive inconvenience only to update through anything and everything and kill battery life regardless. You jeopardised your own usage (because you are inconveniencing yourself) only to kill battery life anyway.

That said… as to the thread topic: if the 5w charger gets unbearably hot as @BigMcGuire said, avoid it. Otherwise I’d just use that one. The device will be charged by the time you wake up anyway.

I enjoyed reading your post.

Yeah it's difficult to destroy an iPhone battery within a few years - I think the best way to destroy one's battery these days is to use a badly designed wireless charger (as it basically cooks the battery non stop) or leaving your phone to cook in a hot car/sun.

I got my wife a Belkin wireless stand after she got her new iPhone 15 Pro Max. CoconutBattery shows a MASSIVE drop when that happened, and the drop continued as she used her phone. A few weeks ago (2+ years later), I tried using her stand and was astounded how insanely hot my iPhone 15 Pro Max was (the battery itself was north of 105F according to coconutBattery) despite being fully charged - the charging contact plate was unpleasant to touch even 30 mins after removing my phone. I believe this led to her iPhone 15 Pro Max battery life being so bad. So we swapped that out for a cable for her before replacing her battery at an Apple Store a few weeks ago. I will be tracking her battery health with this new battery - I expect it to do much better (like mine).

My EV will heat up my battery for supercharging and then quickly cool it down when done - the idea is that rapid charging produces heat so the change from cold to hot a damaging factor to mitigate. Also reducing the time spent at high heat is a key factor as well.

Using a 5w charger, for me, produced an insane amount of heat in the 5w brick itself. The phone was fairly cool (albeit not resting battery temps) but the 5w brick was so hot it yellowed, on two separate Genuine Apple 5w bricks. That's A LOT of wasted energy. A 20w charger or greater doesn't shed as much waste heat (since they're designed for the charging speeds the iPhone wants). I used a Kill-A-Watt and found the 5w brick was pulling several more watts (7-8w) from the wall and that's where the problem lies - it's operating at its thermal / top end which is not as efficient as chargers that were designed for higher speeds.

Also --- in theory, the quicker you get to a full charge and get the battery back down to resting temps the better. So a 5w charger will keep the battery at elevated temps longer (4-5+ hours) vs 1 hour (albeit at higher overall temps but shorter time) - but you get back down to resting temps quicker.

I can only speculate - but I believe the rapid charging and returning to resting battery temps quicker is healthier - and more cost effective vs having the 5w brick shedding tons of heat trying to provide power outside of its optimal curve. But to each their own.

The overall health benefit difference between 5w (4-5 hours) vs 40w (~1 hour) and returning to resting battery temps is minimal - leaving your phone outside in the sun or a hot car or using a wireless charger that cooks your phone will be many magnitudes worse.

There are also factors: Luck of the draw - some batteries will be incredibly resilient and over provisioned from the factory, others not so much.

So just use it how you want. I still say that using a 5w brick will result in a lot of waste heat over the life of the phone - but this is my $.02 and I am not an expert or an electrician - just a battery hobbyist.

 

[BigMcGuire]

Apples 12W charger that came with the iPad Air 3 is a good sweet spot in terms of heat/charging speed. Also a GaN 20W charger will be similar.

One of my favorite chargers - that iPad 12w USB A charger was amazing.

 

[FeliApple]

I enjoyed reading your post.

Yeah it's difficult to destroy an iPhone battery within a few years - I think the best way to destroy one's battery these days is to use a badly designed wireless charger (as it basically cooks the battery non stop) or leaving your phone to cook in a hot car/sun.

I got my wife a Belkin wireless stand after she got her new iPhone 15 Pro Max. CoconutBattery shows a MASSIVE drop when that happened, and the drop continued as she used her phone. A few weeks ago (2+ years later), I tried using her stand and was astounded how insanely hot my iPhone 15 Pro Max was (the battery itself was north of 105F according to coconutBattery) despite being fully charged - the charging contact plate was unpleasant to touch even 30 mins after removing my phone. I believe this led to her iPhone 15 Pro Max battery life being so bad. So we swapped that out for a cable for her before replacing her battery at an Apple Store a few weeks ago. I will be tracking her battery health with this new battery - I expect it to do much better (like mine).

Yeah, that’s why I mentioned wirelessly charging. It generates heat regardless of charger quality. You and I both know that Belkin is good, yet it isn’t enough to prevent your wife’s 15PM from dropping to unacceptable levels. The plate being too hot to touch half an hour later is ludicrous - 5w chargers that heat up are good to go in a few minutes (it has happened to me, though not to the extreme you mentioned earlier). The new battery should perform more normally, even with a fast charger.

My EV will heat up my battery for supercharging and then quickly cool it down when done - the idea is that rapid charging produces heat so the change from cold to hot a damaging factor to mitigate. Also reducing the time spent at high heat is a key factor as well.

Using a 5w charger, for me, produced an insane amount of heat in the 5w brick itself. The phone was fairly cool (albeit not resting battery temps) but the 5w brick was so hot it yellowed, on two separate Genuine Apple 5w bricks. That's A LOT of wasted energy. A 20w charger or greater doesn't shed as much waste heat (since they're designed for the charging speeds the iPhone wants). I used a Kill-A-Watt and found the 5w brick was pulling several more watts (7-8w) from the wall and that's where the problem lies - it's operating at its thermal / top end which is not as efficient as chargers that were designed for higher speeds.

Now, the question is… (obviously assuming no fires, of course) what can the consequence of the 5w charger outputting 7-8w be? Can that performance over-capacity do something to the phone, assuming the charger is “strained” but still functioning normally? Apple stated until they sold it, iirc, that it was compatible with every iPhone. Or is it just efficiency loss and in spite of the yellowing it should be “fine”? (Even though it is obviously not performing as intended. I really don’t think yellowing due to heat is expected behaviour).

I just unplugged my 16 Plus, but it is at 100% so it is trickle charging. I’ll touch the Power Adapter next time I charge it from below 80%.

Also --- in theory, the quicker you get to a full charge and get the battery back down to resting temps the better. So a 5w charger will keep the battery at elevated temps longer (4-5+ hours) vs 1 hour (albeit at higher overall temps but shorter time) - but you get back down to resting temps quicker.

I can only speculate - but I believe the rapid charging and returning to resting battery temps quicker is healthier - and more cost effective vs having the 5w brick shedding tons of heat trying to provide power outside of its optimal curve. But to each their own.

The overall health benefit difference between 5w (4-5 hours) vs 40w (~1 hour) and returning to resting battery temps is minimal - leaving your phone outside in the sun or a hot car or using a wireless charger that cooks your phone will be many magnitudes worse.

This is something I wonder, too: slower (arguably cooler, in spite of the brick itself) charging for longer, or faster (but not too fast and not too hot, like wireless) charging with more heat but a shorter time charging? Say, like I charge once every year or so, a 20w.

Which of those two options is better?

I am inclined to say that they are the same: after all, even with no scientific test, people have shared results left and right; unlike wireless charging which kills health pretty predictably, neither the 5w or the 20w Power Adapters seem to have a negative result.

There are also factors: Luck of the draw - some batteries will be incredibly resilient and over provisioned from the factory, others not so much.

The comparison between adapters seems, like you said, luck of the draw.

So just use it how you want. I still say that using a 5w brick will result in a lot of waste heat over the life of the phone - but this is my $.02 and I am not an expert or an electrician - just a battery hobbyist.

Yeah, that is pretty much my conundrum. I’ve used the 5w for years on end with no negative results. Should strong evidence arise and conclusively prove that the 20w is better than the 5w for every usage pattern, I’ll gladly switch - after all, were that to be the case, then it would be all benefit: faster charging, no heat, and no health degradation more than that for which my usage pattern is responsible.


So I think the conclusion is very simple: use a 5w if it doesn’t get ridiculously hot; otherwise use a 20w. Regardless of your selection, avoid wireless charging and heat, and your device will probably be completely fine.

Some family members cycle their devices a lot more than me. They’ve charged overnight with a 5w regardless of percentage, and the devices are fine. I’m using an iPhone 8 (which, as I dislike breaking tradition I just keep charging with the 5w). 2261 cycles. 76% health. iOS 14. The device is completely fine.

Had it been charged with a wireless charger, the battery would probably be gone. Perhaps even not updating would not be enough to counteract the massive battery failure.

I would not know, because I haven’t degraded an original device enough to know whether a really low health degrades battery life.

Funnily enough… I have a device with battery failure. A family member’s iPhone 6s on iOS 10. It dropped below 80% after one year and 300 cycles. As my motto is “who cares about battery health and replacements, anyway?”, I have it after my family stopped using it. It shows anywhere between 60 and 70% health today. The battery “failed” eight years ago.

Battery life is like-new. 7-8 hours of light SOT, 6 hours of light cellular. It failed eight years ago. I can’t give a better reason for why I don’t care about health than that one.

 

[metsjetsfan]

I used to use the 5W chargers on the theory that less heat during charging was better. The trade-off is that 5W charging is not heat-free, and the battery is exposed to that heat for much longer. I gave up and went to max-rate USB charging and I don't think it's affected the health of the various phones I've owned, although I never did a side-by-side scientific test.

There are other ways to approach this issue. For example, more frequent but shorter charges.

just charge in front of a fan and u have the best of both worlds

 

[BigMcGuire]

just charge in front of a fan and u have the best of both worlds

I use a small USB fan to keep my watch cool during rapid charging. I never get overheated messages anymore. So, it works for my watch, lol (albeit a bit of an inconvenience factor).

 

[1rottenapple]

Ok just buy a cooler a cheap one from Walmart, not those expensive yeti that holds ice for 3 days. Fill it with a small ice pack. Then place the phone 5 inches from the ice pack close it, and charge it overnight. It should keep the phone in the sweet sport of no heating while charging.

You can thank me in 5 years and your battery health is still over 85%

 

[metsjetsfan]

Ok just buy a cooler a cheap one from Walmart, not those expensive yeti that holds ice for 3 days. Fill it with a small ice pack. Then place the phone 5 inches from the ice pack close it, and charge it overnight. It should keep the phone in the sweet sport of no heating while charging.

You can thank me in 5 years and your battery health is still over 85%

haha at that point a replacement battery would be cheaper. A $12 fan on amazon should be fine.

 

[1rottenapple]

haha at that point a replacement battery would be cheaper. A $12 fan on amazon should be fine.

It’s the same principle as charging your phone in the car over the ac vent. This phone holder in my other car places the phone near the ac vent. My phone is cold while charging. OP can always string a long charging wire near the central ac vents or vents of their home ac unit and hanging their phone with modified clothes hanging from the laundry mat.

 

[metsjetsfan]

It’s the same principle as charging your phone in the car over the ac vent. This phone holder in my other car places the phone near the ac vent. My phone is cold while charging. OP can always string a long charging wire near the central ac vents or vents of their home ac unit and hanging their phone with modified clothes hanging from the laundry mat.

haha maybe we should build something and sell it on amazon. after doing all that I think OP could just pay for replacement battery