Is putting the computer to sleep while it's in a hot car a bad idea?

I know that keeping the battery of a MacBook Air in a hot environment is a bad idea. But sometimes I have to leave it in a hot car. Are there any recommendations as to what to do in this kind of scenario?

I'll usually close the lid, which puts it into sleep mode, but I just realized that the battery is probably still being used in that case; and using a battery while it's hot is worse than storing the battery in a hot environment. Is this right? And would the recommendation then be to shut off the computer? What other things are recommended?

According to Apple's webpage:

Hot Tip
If you use your iPod, iPhone, iPad, or notebook in temperatures higher than 95° F (or 35° C), you may permanently damage your battery’s capacity. That is, your battery won’t power your device as long on any given charge. You may damage it even more if you charge the device in these temperatures. Even storing a battery in a hot environment can damage it irreversibly.

Notice the relationship for bad things to do with a hot battery:

Storing < Using < Charging

In other words, the worst thing to do is to charge the device at a hot temperature. Then comes using it, followed by storing it (i.e. storing the battery is the least damaging thing you can do).

So the question is when the device is sleeping in a hot car, is the battery usage (i.e. to keep the RAM data) significant enough that I should be shutting down the computer rather than sleeping it?

Solution 1:

Putting a computer in a hot car is a bad idea. The additional heat, generated by a sleeping MacBook is almost zero.

If you have to leave your computer in the car, and temperatures are (or will reach) near the storage limits (45°C/113°F) you should leave it in an thicker or insulated bag, that will protect the computer from the heat. Avoid direct sunlight at all cost.

Solution 2:

According to the tech specs, you should not store your MacBook Air in temperatures over 45° C or 113° F. While we can assume Apple's specs are a bit conservative (better safe than sorry), doing so might risk damaging your computer, or reducing its lifetime. Note that temperatures inside a car in the sun on a hot day may rise well above 60° C / 140° F.

Being in sleep mode vs. being completely shut down would not make any significant difference, as the battery discharge is neglectible, and while in sleep mode no considerable additional heat is produced by the computer.

The only proper advice I can give you is not leaving your computer in a hot car.