Whether or not your iPhone battery has dwindled down below 20 percent, Taylor says one of the worst things you can do to a battery is expose it to heat, in any form. “When a computer or [phone] heats up, because it’s running performance-intensive apps or processes, that can and does affect the battery,” Taylor says.
One of the worst things you can do when you are trying to maintain your battery power is to stream content like movies and TV shows from YouTube or Netflix apps.
How does this relate to streaming? It’s simple: when you’re streaming, you’re generally running multiple apps and services at once, which requires processing power, heating the internals, and exposing the battery to excess heat,” Taylor says.
Taylor stresses that these devices were designed to withstand some heat, so that alone isn’t the core problem. “What really causes damage is when you expose the device to other forms of heat,” Taylor says. “If you’re streaming outside in heat and humidity or in direct sunlight, even inside, that’s bad news. If you’re streaming near heat-producing items then you might be deteriorating that battery. Some common heat producers include lights, mini-refrigerators, nearby desktops, electronics, stereo equipment, and more.”
It may seem like a minor issue, but over time that exposure can wear down the battery more and more, and might even cause it to fail, Taylor cautions. “The best way to mitigate damage is to try to minimize as much heat exposure as possible,” Taylor says. “Keep the [phone] away from sunlight and heat sources. Disable or close apps that you don't necessarily need. Take breaks, if you can, to let the device cool. Also, don't leave it plugged in all the time, that produces heat too!”