Could a phone at sub-zero (C), heated by load, result in net inc. usage?

Question

Those who've spent time in a sufficiently cold environment (below zero C), and spent time outside with a fully-charged phone, may have experienced taking it out to snap a photo, only to have it suddenly register low-battery life, and then completely shutdown, sometimes within seconds. Mobile phone batteries at sub-zero temperatures lose voltage, and as a result can incorrectly think they have depleted the battery. If cold enough, they will shut down completely. Observing that the same phone, when under certain conditions of high load, can exhibit significant increases in overall temperature; could there be a net positive in terms of usable time, by intentionally ladening a sub-zero degree phone with redundant tasks, with the intention to create sufficiently distributed heat in the phone housing, and therefore warm the battery to the point it performs nominally, resulting in a net positive in terms of being able to use the phone for a longer time - or in extreme cases - at all?

sigmaprimus · Accepted Answer

If I understand what You are asking, I would say the built in heat management design of modern phones would make this ineffective as they intentionally sink heat away from the battery. This is why the phone feels warm under high use.
A more simple solution would be to keep a portable power bank (less than 30 dollars on Amzn)in your pocket and power your phone from it with a long usb cord.
If you dont mind the bulk and have a big enough pocket you can get one with a hand crank, flash light, bluetooth speaker and tuner. If space is an issue there are small ones available that can attach directly to the phone.
A power bank might be a good way to keep your phone warm too, you can pick up a peltier thermal module and usb adapter (less than 10 dollars on Amzn) and tape it to the back of your phone.
Just make sure you dont heat your phone up too much (+30C) as charging lithium cells above that temp will damage them.