E flight bag
I know this topic has been widely discussed on this forum but just in case this aspect has been missed I thought it was worth bringing up. I was flying yesterday with my ipad on my knee, but not actually in use. I guess I was about 30 minutes into the flight and the ipad had been covered for most of that time but had been uncovered with the sun beating down on it for about 10 minutes (it wasn't particularly hot- oat ~20•c- but it was in direct sunlight). Out of curiosity I wanted to look something up about an en route aerodrome, but when I pressed the home button a temperature warning was on the screen and it wouldn't work at all. As I was concentrating on other things I didn't notice how long it had to be left in the shade before it started working again but, having had the same experience with an iPhone on the ground, I know it is not quick.
For me the ipad was doing nothing, other than perhaps getting in the way of the controls, but if you use them for private ops it is worth bearing in mind that more things can go wrong than a flat battery.