I am trying to decide which iPhone model to buy. When I tried iPhone SE in an Apple store, just browsing using the internet browser made the upper part heat up pretty bad. I was guessing if a mere internet browsing does that, perhaps the same thing will happen when using the camera? Is this normal for iPhone SE to heat up on the top portion, with a little activity? Also a family member has an iPhone 6s plus, and I noticed that when charging it with a portable battery that it overheat to a point it was hard to touch the phone. Is this normal? What about iPhone 7+, does it not heat up like iPhone 6 plus does while charging?