I've spent the last week out and about at a festival (it's slowly coming back to me what these are), and in a change to the typical British summer -- slightly less rain than in winter -- it's been hot.
Like 30 degrees C (around 86 degrees F). And that's outside. Get inside a vehicle or building, and it can be much hotter.
While I was at the festival, chilling with my drone (it makes quite a handy, albeit noisy, fan), a fellow came over to me to ask if I knew what was up with his phone.
It wasn't phone-shaped anymore.
And it was blisteringly hot to the touch.
Initially, I thought it might have been a case of a battery going into thermal runaway, but on talking to the chap, things became clearer.
He'd left his phone -- a nice gold iPhone 12 Pro Max -- in the holder stuck to his car's windshield all day, and the phone's battery had popped the display out of the frame.
It was the end of the road for this iPhone.
Now, the weird thing is that it's not rare to see phones in holders stuck to car windshields in summer, baking away.
And it's not just while the car is still -- a phone in the window can get hot while the car is running, unless you have it in the direct flow of the aircon.
But leaving them there to bake inside a hot car isn't great for the battery. In fact, overheating a handset -- and remember that most of the time phones are in holders nowadays, they're also charging -- is a surefire way to wear out batteries.
Over the past few weeks, I've seen or heard about half a dozen dead phones and a couple of in-car GPS receivers giving up the ghost in the heat. The heat is not only brutal for the batteries, but it can also damage the displays.
It's not just a problem in the car. It's just as much a problem at home or the office.
And it's not just a problem for phones. It's not a good idea to bake anything that contains a battery that you care about.
Here's my rule of thumb: If the phone feels hot to the touch, find somewhere cooler for it. The battery might work fine in summer while it's warmer, but it's wintertime that people see the side effects of battery degradation when their smartphones start showing reduced battery life.
If the phone is too hot to the touch, you need to take it off charge, take it out of any case it's in, turn it off, and allow it to cool down.
And find a better spot for it in the car, home, or office.