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Comment by AdamH12113 | Hacker News Reader

115F is 46C.

I was surprised to learn that iPhones and iPads are only specified to operate between 0-35C (32-95F) ambient[1] -- even cheap consumer-grade ICs typically work up to 70C/158F. 95F/35C is a perfectly ordinary outdoor temperature during the peak of summer in America's south, and temperatures below 32F/0C are common anywhere it snows. (0C is the standard lower limit of the consumer temperature grade, however.)

I suppose cooling such a small, dense device much be difficult, and having everything pressed against the battery (with its presumably lower temperature limit) probably doesn't help either. Still, I feel like a portable electronic device ought to be able to work in places other than California.

[1] https://www.apple.com/iphone-14/specs/

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Yeah I have been collecting these stats on my own devices about their operating temperatures and I'm often surprised how much smaller the range is than I was expecting. For example:

Kobo eReader: 0 - 45C

Pixel 6: 0 - 35C

Macbook Pro: 10C - 35C

Pixel Buds: 0 - 35C

Garmin heart rate strap: 0 - 40C

Garmin bike computer: -20 - 60C

From talking to manufacturers I often hear "it will probably work outside this, but you'll have worse battery performance and eventually issues will arise". Another thing I hear is that, below zero, for wearable devices they will often stay at an OK temperature if they are in a pocket or beside your body.

Garmin's strategy makes sense: a heart beat strap benefits from your body's temperature regulation, both to keep cool and keep warm; a bike computer has to take what it gets, but at least gets a lot of convection to keep temps reasonable when it sits in the sun.

I'm most surprised that a MacBook Pro with its active cooling doesn't have a higher max temp than a smartphone.

Active cooling effectiveness depends significantly on the delta between incoming temperature and the heat source temperature, and the relationship is worse than linear I think.

Newton's Law of Cooling shows it's an exponential decay in heat transfer rate as the delta decreases.[1]

[1] https://en.wikipedia.org/wiki/Newton%27s_law_of_cooling

That was my intuition but it's not my field and I'm too lazy to look it up so I really didn't want to spread more precise but less accurate info.

My concern about Garmin's strap was mostly that I do a lot of running below 0 in the winter but to their credit their support was very helpful and said it was unlikely to actually damage the HRM device given the conditions I described -- they even offered to send me some free batteries since I might go through them quicker.

In 2019, Chris Siebenmann discovered that the bitter Canadian winters were taking a toll on his desktop machine at home: https://utcc.utoronto.ca/~cks/space/blog/tech/ColdLockupMach...

The earbuds seems particularly odd given that an ear canal is close to human body temperature (~36C) to begin with.

The human body is ~36C only internally. I just used an IR thermometer, and the inside of my ear canal is currently 32C, plus a large portion the earbud is external to your ear canal.

EDIT: Out of curiosity I also measured the temperature of my airpod at the ear canal tip - 27C.

The human body varies and it may also be 37.5C. Sick people even more. Might still want to use earphones. Ear canals get pretty close to core temp, as they're near the brain. If you're measuring 32C either you are in a cold environment or you might be misaiming (these things aren't that easy to use, or very accurate).

In a warmer climate, the delta gets even less. So yeah, it's a bit surprising that wearables aren't rated for body temperature.

> able to work in places other than California

They don't even work in California. I bought a new Pixel last summer and a few weeks later, was running around San Jose on a day that was around 95-100F (car doesn't have working AC). I left my phone on the front passenger seat in the sun for a few minutes and was getting warnings about the device overheating, apps were running terribly, and I had issues for some weeks after.

And that's in the Bay - most of my friends live outside of it, where highs of 110F aren't uncommon.

The sun heats very well and temperatures are measured in the shadow for a good reason. Putting a phone in the sun is simply not a good idea and definitely not helpful when it comes to the question of how much heat such a device should withstand.

> Putting a phone in the sun is simply not a good idea

I get what you're saying, but this is setting a very, very low bar for robustness.

The point is that putting a device in the sun will rapidly raise it's internal temperatures past its operating limits.

"on a day that was around 95-100F" When you add solar heating that device is going to get hot and quickly. The internal temperatures of the SOC and battery will be out of range and the device will need to shut down to cool off.

You have to account for the heat of the phone itself. It is not unusual for CPUs to operate at 90 degrees celsius.

Modern phones have a lot of power, generate a lot of peak heat from their SoC but has the worst possible cooling scenario - held near hit skin, covered in leather cases, etc. When you start at 35C you only have 25C left until the mentioned 70C, which components near the SoC Would quickly surpass.

Higher rating is unlikely to help much - you need less heat generated or better heat dissipation.

Reporting in from the American South, it's been super hot lately and if I have my iPhone in my pocket while doing anything outside remotely active it starts acting up after a few minutes. It can be pretty rough when I'm trying to do yard work

The reason for this is that while all the individual electronic components, the PCB, and even likely the peripherals such as the display panel, are all very likely rated for at least 70-85C, the lack of active cooling in smartphones is why an ambient temperature of >35C would spell disaster for smartphones (fortunately due to temperature awareness of the SoC, the SoC just shuts off).

Even though the smartphone SoCs may dissipate around <2W of heat, to transfer that heat out of the chassis is pretty hard. This is coming from experience from working on a consumer electronics product where we have run at least 20 heat simulations on Autodesk and learnt how tough it is to dissipate out even 0.75W heat.

My iPhone usually stops working if I lie in the sun using it for tethering and it's in the sun. I have to put a sunshade over it. This is in London which is not super hot usually. Though I'd say at a high temp than 35. It's probably like 50C when it stops working I'd guess from feeling it.

I'm guessing iPhone was designed to be used in airconditioned malls and office towers. Like how the only people you see outside in Kuwait are migrant workers.

When I'm sitting on my South facing apartment balcony I can't use my phone which is annoying.

The O°C lower limit sounds optimistic for a li-po battery, unless you don't care about how many minutes it operates.

In Minnesota the winters can easily fall below -20C consistently and I’ve never had my phone stop working outside.

I keep my own phone in my pocket so it's unlikely to have a problem, but I've seen one die quick kept in a bag and we weren't really sure if temperature was the cause..

My first phone (a Motorola flip phone) bit the dust after some time in my pocket walking around below freezing temperatures. Some cells within the battery burst/swelled so the battery casing pushed away from the phone and lost contact. If I pushed it in, it worked as long as I maintained contact with the pressure.

I’m young enough I’ve only ever used iPhones really so idk what it was like in the 90s-2000s.

How can a simple comment make my back hurt?

Cold isn't usually a problem so long as you take proper precautions to not allow condensation to form inside the phone when warming it back up again - that's what electronics manufacturers are concerned about.

VHS VCRs used to suffer from condensation issues, and some had sensors for this: the display would show "DEW" if it detected internal moisture, and you've have to wait before inserting a tape.

Running the phone would warm up the battery.

Huh, only 35c?

And here's I was surprised my s22 was only rated to 40c...

it gets well over 95 degrees in socal often. today even.

Yes, easily. I'm surprised to see this, honestly. I've never had detectable problems with my devices when I am outside in the heat but I will be more conscious of this going forward. 35C is frankly laughable.

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