Telephone operating temperatures

[RangerZ]

I had something new happen to me yesterday. I went out for a local day hike, temperature was right about freezing. About half way through the wind came up and I stopped to put on a wind jacket. The temps seemed to have dropped so I tried checking on my Iphone. I couldn’t get it to access the internet, weather, messaging, etc. Also finger didn’t work well on the touch screen. I could make calls. I had the phone in my front pants packet. Checked it after I came home and it worked fine. I checked the websites and they give operating ranges down to freezing (and up to 95*). Beyond that: “Low- or high-temperature conditions might cause the device to change its behavior to regulate its temperature.” Keep it between -4 and 113* otherwise.
Before I had my old flip phone out in 17* and it worked fine. I guess its part of the cost of technology.
Another item to sleep with in the sleeping bag – filter, glucometer, phone and me.

[peakbagger]

Many I phones display a warning phone is too hot and must be cooled prior to using. Its interesting to see the warning below zero. I guess the programmers in Southern CA, can envision using a phone in below zero weather.

[Mudsock]

In cold weather, anything battery powered is at risk for reduced performance due to the battery chemistry. With phones and GPS devices the LCD will also have performance issues.

Keeping these devices in an inner pocket is good practice. The thermal mass causes the temperature to change slowly. Even in extremely cold weather, you can expect a warm phone to function for a good amount of time.

The other electronics in a phone or GPS should be much less prone to temperature problems. The base emitter voltage (Vbe) of a bipolar transistor is inversely proportional to temperature. A small change in Vbe can result in large changes in collector current. Low power devices use primarily Field Effect Transistors (FET), rather than bipolar transistors. The on channel resistance of a FET (RdsOn) is directly proportional to temperature. For low power devices, that is not as much of a problem as with high power devices such as with the FET switches in your car's engine computer.

When testing electronic devices prior to production, they are exercised at design temperature extremes and often temperature cycled between two extremes to identify problems. Repeated cycling of electronic devices between high temperature and low temperatures causes thermal stress - physical stress. Some devices will be in compression, others in tension. In testing of automobile electronics, the devices are often cycled between -40 and +125 degrees C. There may be 500 or more cycles between the temperature extremes in the validation schedule. Solder cracks are not uncommon. The damage occurs at the extreme cold temperature because the stress is maximized at that temperature. Solder reflows during manufacture at a temperature above 200 degrees C. That is the no stress temperature. Going cold causes stress because different materials expand or contract at different rates as temperature changes. All of this to say that exposing your phone or GPS to a Minnesota winter without protection is hard on it. It likely won't fail the first time, but repeated cycling takes a toll. Keeping a GPS and phone in the sleeping bag is not a bad decision when it is extremely cold from a damage standpoint. Considering the battery performance, keeping these devices warm (not hot) is always a good idea.

Many devices are assembled with conductive epoxy, rather than solder. The epoxy cure temperature is the no stress temperature. Cure temperatures of epoxy are lower than reflow temperatures of solders.

With temperature it is not just operation that we need to be concerned about. We need to be concerned about shortened life, as well. Still, few consumer devices other than automobiles are expected to be repeatedly cycled between -40 and +125 degrees C. -40 C is -40 F.

[MamaBear]

This is not uncommon with the iPhone 5. I hike just about once or twice a week, even in winter, here in the Whites of New Hampshire, and I use my phone for multiple things, so I've seen that message before. I have other hiking friends it has happened to as well, especially when the phone is stored in an outside pocket or pouch. It also happened to a good hiking friend who left his full size iPad in the car while we were out all day back in December.

My current solution for continued use of the phone is to put one chemical hand warmer packet (Hot Hands is one brand) in with my phone in my holder and that has worked very well, even in ambient temperatures of single digits. I gave my partner an extra hand warmer packet on a long trek this past Saturday after he showed me the message on his phone, and once the phone was warmed up again, it functioned perfectly for the rest of the day.

I agree with Mudsock, battery life is also compromised by the cold. I carry an external battery pack so that I can keep the device charged, too.

One other option is not to use your phone at all and keep it buried in the pack. Of course, that is a highly individual choice; there is quite a wide range of opinions regarding the usage and the actual usage of electronics on the trails. For those who like tracking apps, GPS functions, listening to music and use their phone as a camera, keeping it in the pack might not be as appealing.

[peakbagger]

One minor misconception. Battery life is generally not impacted by the cold. The battery still has a charge its just not chemically available to be used. If you warm up the battery, the charge will return.

[MamaBear]

Hmmm, that's interesting, peakbagger. So it isn't the actual battery, but the connection to get the power between the battery and the functioning part of the device? I've taken my phone out to take a picture, check distance, whatever, had somewhere in the 35% charge range and in seconds, the phone can be down to 1% and then even give me the "plug me in" symbols. So, if I just rewarm it, theoretically the % charge should be back in a similar range to when it all of the sudden dropped, right? I'll have to experiment with that and see what happens. Not like we won't have cold and snow for a while longer. :)

[Starchild]

Hmmm, that's interesting, peakbagger. So it isn't the actual battery, but the connection to get the power between the battery and the functioning part of the device? I've taken my phone out to take a picture, check distance, whatever, had somewhere in the 35% charge range and in seconds, the phone can be down to 1% and then even give me the "plug me in" symbols. So, if I just rewarm it, theoretically the % charge should be back in a similar range to when it all of the sudden dropped, right? I'll have to experiment with that and see what happens. Not like we won't have cold and snow for a while longer. :)

No it is the battery itself that in the cold that simply can not give the 'normal' chemical reaction and some of it is locked up in the cold, reducing available energy.

That said the energy comes again available when it is warmed.

[ATAdam]

Galaxy S4 - broke at -26 working a delivery in Williston, ND - forgot it in my outside jumpsuit pocket. Droid Maxx I've forgot in my jumper pocket and well into the -20s did not break.

Depends on the phone and the luck. Flip phones are low tech and less to break. If I didn't have a GPS that was smart phone dependent I'd bring a flip on my AT run this year.

[peakbagger]

I would guess that there is some sort of internal temperature indicator that responds more rapidly than the battery that actually tells the operating system to send a warning.