Why you should NEVER charge your phone with its case on, according to repair experts

Sometimes what protects the outside of your phone can damage the inside of your device.

While plastic, rubber, and silicone-based smartphone cases are great for absorbing shock from drops and keeping liquids out, these materials can act as insulation, trapping heat around your device like a warm sweater.

Phone cases made of luxurious leather and even vegan leather can have the same effect.

This may be a good thing in icy weather, but according to Guidelines from Apple on maximizing battery performance: “Charging your device while it’s in certain cases can cause excessive heat build-up, which can affect battery capacity.”

So if you notice your phone getting hot while charging, you may want to take it out of the case in the future.

According to Apple, the iPhone and other iOS and iPadOS devices, including the Apple Watch, all work best in an ambient temperature of 0° to 35°C.

When simply stored away, that range of “comfort zone” temperatures is a bit more generous, -4° to 113°F (-20° to 45°C).

But according to experts, Apple engineers have designed their devices for peak performance at room temperature. The true sweet spot is between 62° to 72°F (16° to 22°C) whenever possible.

So while even some of the thickest phone cases won’t cause serious overheating on their own, they will add to the overall warming alongside factors such as battery age, internal wear and tear in the battery, or just the weather that day.

Adrian Kingsley-Hughesauthor of The PC Doctor’s Fix It Yourself Guide, conducted an experiment to charge his iPhone 13 Pro Max in several cases in a room with an ambient temperature of 20°C.

Kingsley-Hughes found that lower power 5W charges managed to keep his iPhone in its “comfort zone,” regardless of which phone case was used.

However, high powered USB-C chargers showed signs of heating the iPhone a little too close for comfort, especially when trying to use the phone while it was still charging.

In general, he says silicone cases kept the phone cooler than rubber cases.

His conclusion: downgrading to a slower 5W charger can help, whether in warmer climates or if someone doesn’t feel like constantly taking their smartphone out of its case and putting it back in.

Overcharging or undercharging can also affect your phone’s battery life.

Chinese manufacturer Huawei recommends that users keep their device between 30 and 70% charged for the best battery life. And Apple actually has a special setting that ensures your phone never goes past 80% or so to save battery life.

But when it comes to your phone’s battery life and temperatures, the rule of thumb is to avoid extreme temperatures as much as possible.

If Apple’s support site warns, “Using an iOS or iPadOS device in very hot conditions can permanently reduce battery life.” For example, “Don’t leave your device in your car, as the temperature in parked cars can exceed this range.”