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My new iPhone 5 (I preordered mine from AT&T on the morning of the 14th and received it on the 21st, so I might have one from one of the earlier batches) likes to heat up intermittently.

I've noticed a general correlation between the cellular connection display showing "4G" and when it tends to heat up by itself. It seems generally capable of heating up to a temperature higher than it would get to from just being in my pocket, and just to be sure I have left it on a table and observed the same effect.

What's curious to me is that whenever the display shows "LTE" this effect is not as pronounced. When I'm at home I usually see LTE but at work it spends a good half of its time in "4G" mode and this warms it up and sucks the juice out of it real quick. The data connection is definitely faster on LTE mode also.

All of this seems to indicate some sort of software bug with the 4G cellular hardware in the device, as it makes no sense why it should struggle more when connecting to what appears to be a slower network. I hope that Apple is aware of this and that it may be addressed in the near future.

Has anybody else noticed this issue with their iPhone 5? I have searched a bit on Google but it looks like everybody is pretty much too busy playing around with their new gadget to complain about (or notice) this particular issue I have. My thinking is if lots of people also experience this issue it's more likely to get addressed.

Update: I have found this page which more or less reflects what I am seeing, except my observation is that low signal "4G" causes very high power draw. If I need to make an emergency call I could justify this level of power consumption. But calls do not require high speed data connections.

I just hope I don't have to wait for the jailbreak before this becomes fixed, in fact I really doubt a jailbreak would allow me to tweak radio hardware either.

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The radios on the iPad crank some serious heat when LTE is sending a lot of data (for obvious reasons) and it will be interesting to see what the range of heat output is on this device. This could all be normal since LTE allows the chipset to get the data and be done, and lower speed transmission means the device is spending more "duty cycle" time active and generating more heat. If you are a developer you can place the phone in instruments and graph things like CPU load and more if you want to dig deeper on how the system is really working. – bmike♦ Sep 25 '12 at 19:34
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It should be noted that, on AT&T, "4G" means HSPA+ and "LTE" is LTE. HSPA+ is (functionally and technically) 3G+ (i.e., improved 3G) and will use different frequencies and different hardware than LTE. It may simply be that HSPA+ uses more power than LTE. – CajunLuke Sep 25 '12 at 19:37
Yesterday my battery was at about 35% after just over 2 hours of usage reported under Usage in Settings. That can't be right. I can definitely expect 10+ hours of browsing or even movies on wifi since it seems to be very power efficient when not using 4G but at this rate would have been be empty at just over 3 hours of usage... – Steven Lu Sep 25 '12 at 20:47
Good - you'll want to get a baseline - full to empty benchmark without charging it during the day to see what usage you get from the new device. That will help once you start determining what settings draw power more than you like and tuning things. Also - if you're close to a store you can have it scanned by the genius bar to ensure the internal temp sensors are working and the hardware checks out. – bmike♦ Sep 25 '12 at 21:04
I got particularly bad LTE service at work today and it is mostly 2 bars on HSPA+. Browsing sites (It's not like I am running speedtest over and over) has the thing reaching very high (feels like 40C) temperatures on the casing. It is clearly drawing so much power that the battery would fully drain within 3 hours. The problem is mainly that I cannot find a spot where I can always get the same type of weak signal. – Steven Lu Sep 26 '12 at 21:32
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closed as not a real question by Nathan Greenstein♦ Oct 4 '12 at 15:51

It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, see the FAQ.

1 Answer

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There is no question in your question. What are you asking for?

I'd take it back to the Apple store.

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Like I said... good signal, average signal, no problem. Battery life is fantastic. Low signal: drains fast. Updated the OP. – Steven Lu Sep 27 '12 at 3:55
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Don't say "Like I said.." when you didn't ask a question the first time. You returned and edit your "question" to inject a question. Before that edit you were just rambling and stating some complaints. This is a Q&A site, so jump straight to the question. – Sid Oct 4 '12 at 15:44

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