Thoughts on Reducing Charging Heat for Apple Watch

[BigMcGuire]

Some thoughts on my new Apple Watch Ultra 3 ... the charging speed is insanely fast but it gets quite hot. My Apple Watch Ultra 2 would often complain about being too hot (using same charger) and pause charging...

For fun - I've played around with putting my Ridge wallet (metal) on the charging puck to draw off some of the heat and noticed with my AWU2 it would prolong the time I could rapid charge before getting the too hot message. I also put the Ridge wallet on the top of the watch face as well as also experimenting with turning the watch upside down so the charger's rear was facing up - and then put the wallet on the charger. These seemed to have a marginal impact on the overheating message appearing (it still appeared) - and I wonder if this setup made it worse since once the wallet's metal surface got saturated, the heat had nowhere to go instead of bleeding off? Not an expert here.

I do have a slow USB A watch charger and it charges 4x slower but interestingly enough, gets almost as hot regardless of the slower charging speed.

I have yet to get an overheating message on my Apple Watch Ultra 3 but it has gotten fairly hot the few times I've charged it so far.

Thoughts?

 

[jz0309]

Some thoughts on my new Apple Watch Ultra 3 ... the charging speed is insanely fast but it gets quite hot. My Apple Watch Ultra 2 would often complain about being too hot (using same charger) and pause charging...

For fun - I've played around with putting my Ridge wallet (metal) on the charging puck to draw off some of the heat and noticed with my AWU2 it would prolong the time I could rapid charge before getting the too hot message. I also put the Ridge wallet on the top of the watch face as well as also experimenting with turning the watch upside down so the charger's rear was facing up - and then put the wallet on the charger. These seemed to have a marginal impact on the overheating message appearing (it still appeared) - and I wonder if this setup made it worse since once the wallet's metal surface got saturated, the heat had nowhere to go instead of bleeding off? Not an expert here.

I do have a slow USB A watch charger and it charges 4x slower but interestingly enough, gets almost as hot regardless of the slower charging speed.

I have yet to get an overheating message on my Apple Watch Ultra 3 but it has gotten fairly hot the few times I've charged it so far.

Thoughts?

are you using the puck that came with your U3? The U3 is designed to be charging fast, I'd expect Apple to have tested this type of fast charging and found none or very minimal impact to the battery/watch.

If it is a big concern, get AC+.

Me, I charge bot my U2 and my S7 on the puck that came with the S0, over night, so I have no idea how hot they get.
I do charge the U2 on a U1 puck plugged into my Studio Display, it's charging after but I only do that when watchOS updates are installed (the stupid 50% and on charger requirement), it gets warm but never it felt "hot", to me.

 

[BigMcGuire]

are you using the puck that came with your U3? The U3 is designed to be charging fast, I'd expect Apple to have tested this type of fast charging and found none or very minimal impact to the battery/watch.

If it is a big concern, get AC+.

Me, I charge bot my U2 and my S7 on the puck that came with the S0, over night, so I have no idea how hot they get.
I do charge the U2 on a U1 puck plugged into my Studio Display, it's charging after but I only do that when watchOS updates are installed (the stupid 50% and on charger requirement), it gets warm but never it felt "hot", to me.

Yeah using the Apple one - my AWU2 had 99% health after 2 years too so - I don't think it hurt anything to get those messages either. So probably overthinking this. (More of a fun hobby - not out of necessity).

 

[jz0309]

Yeah using the Apple one - my AWU2 had 99% health after 2 years too so - I don't think it hurt anything to get those messages either. So probably overthinking this. (More of a fun hobby - not out of necessity).

FWIW, I've lived in SoCal for 20 years now, I do not recall ever seeing a "too hot" message on any iPhone or AW I ever owned.
I know that Qi charging in cars can drive temps quite up, but I rarely do that.
My old Bolt EUV had a Qi charger that was quite good, didn't heat up the phone much and charged fast, haven't tried the wireless charging in my Ioniq 5 in the past year
Good thing, just like computers, the OS knows when the device is getting too hot and throttles or even shuts down, built-in safety guard.
I haven't looked at the operating temperature range for my U2, but there is a reason there is that spec.

And not that you said anything about it, but the battery obsession here on MR is just that, an obsession. computing devices are tools, and tools get repaired/replaced when they don't do the job anymore, just my take.

 

[BigMcGuire]

FWIW, I've lived in SoCal for 20 years now, I do not recall ever seeing a "too hot" message on any iPhone or AW I ever owned.
I know that Qi charging in cars can drive temps quite up, but I rarely do that.
My old Bolt EUV had a Qi charger that was quite good, didn't heat up the phone much and charged fast, haven't tried the wireless charging in my Ioniq 5 in the past year
Good thing, just like computers, the OS knows when the device is getting too hot and throttles or even shuts down, built-in safety guard.
I haven't looked at the operating temperature range for my U2, but there is a reason there is that spec.

And not that you said anything about it, but the battery obsession here on MR is just that, an obsession. computing devices are tools, and tools get repaired/replaced when they don't do the job anymore, just my take.

Was in SoCal from 89 - 2023 - hah! We're in NorCal here for 3 years (this should be our last year (till Sept 2026)). We'll see where life takes us after that but... /wave from a fellow socal

Yeah I'm very happy Apple is taking a pro-active approach to this - I'd rather have them stop the charging than harm the battery. I only get it in the summer here - my tiny little apartment in NorCal faces the sun (even with the blinds closed it gets hot!). And despite 2 years of that with my Apple Watch Ultra 2 - health was still 99% - so yeah you're right, best not to think about it too much. Also, pretty sure me trying to dissipate the heat with my wallet only made things worse (saw the warning more).

Yeah, it's cheap enough I shouldn't worry or think about it. My wife gave me this AWU3 for my birthday so - hoping to make it last a long time (I'll just replace the battery when it gets low - like you said).

I appreciate the help and encouragement to reality

 

[Jackbequickly]

I charge my S11 every night using an old Apple 5watt charging block and it never even gets warm. I am in no hurry and it is always fully charged in the morning.

 

[BigMcGuire]

So, I found a "solution" - and please note, this is a hobby, something I'm doing for fun, not something I recommend... I found a way to keep the watch cool while fast charging.

I have a fan that's about half the size of a normal fan, and I put the watch on its side, and I put the fan on medium power directly on top of the watch (resting on it), and the airflow keeps the watch completely cool while charging. Note I only charge while showering, so this isn't an inconvenience - no more burning hot watch after I get done getting ready for the day.

Probably won't have any impact and if it does - probably'll be years before it is apparent.

Just an FYI.

 

[Tdude96]

Out of curiosity, what is the ambient temperature while charging?

I've never seen a high temperature warning while charging any Apple Watch or had it stop charging, even in the summer when it can get to be around 80ºF in the room where I keep the charger. However, I also don't charge it flat, so I'm wondering if that has something to do with it. I've got one of these https://www.thingiverse.com/thing:4361038 so heat doesn't tend to rise up into the body of the watch. Perhaps that's enough.

 

[BigMcGuire]

Out of curiosity, what is the ambient temperature while charging?

I've never seen a high temperature warning while charging any Apple Watch or had it stop charging, even in the summer when it can get to be around 80ºF in the room where I keep the charger. However, I also don't charge it flat, so I'm wondering if that has something to do with it. I've got one of these https://www.thingiverse.com/thing:4361038 so heat doesn't tend to rise up into the body of the watch. Perhaps that's enough.

Side note: We've been having some high humidity here in NorCal... Not sure if that's the cause? I'm constantly sweating unless I have moving air.

I don't have a thermal monitor --- I started getting overheating notices on my Apple Watch Ultra 2 earlier year in the summer time. I'd open the battery menu in the settings and see that charging was on hold due to temperature. Health was 99% so I wasn't terribly worried but... I never had that warning before either... but the AWU2 charges FAST and always got really hot.

So I started experimenting with putting a metal object on the watch (or the base) to try to draw away some heat (post above) - I noticed the watch got a lot further along before still eventually overheating. It overheated regardless of being upside down, on the side, or on a big metal base. :/

Upon getting my Apple Watch Ultra 3 - I didn't get the heat warning but the watch got just as hot. So I started experimenting. Grok mentioned using a small fan to keep the airflow going so the watch can shed heat and ... viola, it worked. Watch remains cool to the touch while charging and is cold when I put it on my wrist.

Doesn't take much effort so I think I'll keep doing this for now. I use a battery powered fan (half size of a desk fan) - and tip the watch at a \ angle and put the fan down on top of it (holding watch at the angle) and turn the fan on.

 

[Howard2k]

So, I found a "solution" - and please note, this is a hobby, something I'm doing for fun, not something I recommend... I found a way to keep the watch cool while fast charging.

I have a fan that's about half the size of a normal fan, and I put the watch on its side, and I put the fan on medium power directly on top of the watch (resting on it), and the airflow keeps the watch completely cool while charging. Note I only charge while showering, so this isn't an inconvenience - no more burning hot watch after I get done getting ready for the day.

Probably won't have any impact and if it does - probably'll be years before it is apparent.

Just an FYI.

I don't "worry" about the heat, but at the same time I try to avoid long charge cycles because of heat. As @jz0309 says - the watch monitors for heat anyway. I do have a variety of slow and fast chargers, but in general I like to keep it above 50%. Anything above 80% I don't generally bother topping up. It sounds like micro-management but it's really not. I charge it while in the shower or doing the dishes, or maybe while stuck at my desk on a conference call, and that seems to be enough to keep it with enough power reserve to be comfortable most of the time. And I do know that if I'm charging on colder day it's going to be slightly more efficient than charging on a warmer day.

And they say that heat is the real enemy of batteries, so short charging periods would also help in that regard too.

Does it make a difference? I'm not sure, but I doubt it hurts and it doesn't inconvenience me so it seems worth a shot.

A long workout still gives it a beating of course.

It was good to see a battery extension, ever so slightly, in the new generation but I look forward to a real leap in that regard and then charging becomes far less of an issue.

 

[Tdude96]

Doesn't take much effort so I think I'll keep doing this for now. I use a battery powered fan (half size of a desk fan) - and tip the watch at a \ angle and put the fan down on top of it (holding watch at the angle) and turn the fan on.

Yeah, even moving a little air helps. I run local image generation on my MBP, which makes the machine nice and toasty. Just mounting a tiny fan to blow across it and move the heat away does wonders. It still gets hot, but stays far cooler than without.

 

[jz0309]

So, I found a "solution" - and please note, this is a hobby, something I'm doing for fun, not something I recommend... I found a way to keep the watch cool while fast charging.

I have a fan that's about half the size of a normal fan, and I put the watch on its side, and I put the fan on medium power directly on top of the watch (resting on it), and the airflow keeps the watch completely cool while charging. Note I only charge while showering, so this isn't an inconvenience - no more burning hot watch after I get done getting ready for the day.

Probably won't have any impact and if it does - probably'll be years before it is apparent.

Just an FYI.

So, since this is a "hobby" I'd like to suggest a few things for you to try:
. Water, the Ultra is rated for recreational scuba diving so I think you should put it in a container of ice cold water while charging
. Refrigerator, get a power bank and try charging in refrigerator as well as the freezer

Document results and report back please.

 

[Howard2k]

Those are actually great ideas but I'm not sure that the charger is submersible.

Fridge with a MagSafe power bank would be interesting though.

 

[jz0309]

Those are actually great ideas but I'm not sure that the charger is submersible.

Fridge with a MagSafe power bank would be interesting though.

Well, the puck definitely is submersible, the question is, will water get in it?
Looking at the older pucks (the ones with the non-braided cables) I am quite confident that no water would get in there, esp since you'd only need to submerge it for an inch or two.

So @BigMcGuire go for it!!!

 

[BigMcGuire]

One way to test a gfci circuit, lol. Definitely not going to put something connected to an outlet to a water source - lol.

Fridge - my thoughts are - unless there is moving air, you'll still have the problem with heat being generated locally - but if the watch is able to distribute the heat to a frozen area that has a lot of contact with the watch face/body - maybe that would work. The convenience factor here goes down big time.

The fan is doing great - I run a fan every night while I sleep so it's right next to my bed anyway, so that works to use it to dissipate heat easily when I get ready in the morning. Not that doing this will have any significant impact on battery life - I fast charged my AWU2 for 2 years and it still had 99% health.

 

[goldmac2006]

Some thoughts on my new Apple Watch Ultra 3 ... the charging speed is insanely fast but it gets quite hot. My Apple Watch Ultra 2 would often complain about being too hot (using same charger) and pause charging...

For fun - I've played around with putting my Ridge wallet (metal) on the charging puck to draw off some of the heat and noticed with my AWU2 it would prolong the time I could rapid charge before getting the too hot message. I also put the Ridge wallet on the top of the watch face as well as also experimenting with turning the watch upside down so the charger's rear was facing up - and then put the wallet on the charger. These seemed to have a marginal impact on the overheating message appearing (it still appeared) - and I wonder if this setup made it worse since once the wallet's metal surface got saturated, the heat had nowhere to go instead of bleeding off? Not an expert here.

I do have a slow USB A watch charger and it charges 4x slower but interestingly enough, gets almost as hot regardless of the slower charging speed.

I have yet to get an overheating message on my Apple Watch Ultra 3 but it has gotten fairly hot the few times I've charged it so far.

Thoughts?

Not an issue on my end but my third party Merkury Innovations Apple Watch portable charging puck does heat up when used for a long time which causes the slow charging. That one I only use when I’m on the go like in school (now only use it when I have to take off and put my watch away for exams) or traveling

As always I use the OEM Apple charger when I’m at home. Mines isn’t usb c but my watch only heats up when it’s updating. It charges faster than third party

I use my power strip’s usb A ports connected to the charger on my dock. On the go I use an adapter or a power bank