Is It Okay to Charge iPhone Overnight

If you’ve ever left your iPhone to charge overnight, you are certainly not alone. Many smartphone users, including iPhone users, are used to leaving their phones charge overnight.

However, overnight charging has always been discouraged. It is a common opinion that leaving just about any smartphone to charge throughout the night can damage its battery life. If you want to know whether this is true, the short answer is yes, but not in all cases.

Charging Mechanism in Your Phone

All iPhones use Lithium-ion batteries. The  Lithium-ion batteries on your iPhone are made up of a cathode, an anode, and a separator. When your batteries are at full charge, the Lithium-ions are all situated at the anode side of your battery.

They slowly trickle to the cathode side, generating power in the process. The more the Lithium-ions move to the cathode side, the more your battery charge drops. On the other hand, when you charge your iPhone, the Lithium-ion starts moving back to the anode side.

When your iPhone is at full charge or very low charge, the battery is under stress due to the Lithium-ions pooling at one side of the battery. So, the myth about not letting your battery charge fall below 20% or exceed 80% is actually true.

If you want to know more about the mechanisms of charging, you can find more information in our other article.

What Happens When You Charge an iPhone Overnight?

Degrades Battery Life

Charging your iPhone overnight will cause your battery life to degrade faster, but not for the reasons you think. Overnight charging is mostly discouraged due to the belief that leaving your phone charged for long will overcharge your phone.

However, this really isn’t a cause for concern as iPhones and almost all smartphones stop charging after reaching 100% charge. There is no risk of overcharging.

Overnight charging harms your battery life because of something called trickle charging. It happens when your iPhone reaches 100% charge and it stops charging. However, the normal background process will consume your iPhone’s charge and drop it back to 99%. When this happens, the charger kicks back in and starts charging your iPhone again.

This cycle happens all throughout the night, which makes your battery life degrade faster over time.

The Optimized charging feature learns your charging habits and usage pattern. Whenever you charge your iPhone overnight, it will continuously charge till 80% after which it stops. The charge resumes back when it is close to your waking time according to the usage pattern and starts charging the phone to 100%. Thus, eliminating the problem of trickle charging.

Overheating

Your iPhone can also overheat when you leave it to charge for a prolonged time. While newer models of the iPhone do not suffer from this problem as much as the older models, you should still be careful.

The overheating can get especially worse if the heat has no way to escape. Charging your iPhone overnight below your pillow is a surefire way to overheat and damage your battery.

Furthermore, if you charge your iPhone at a power outlet that has multiple other electronics connected to it, your device will overheat even more.

Adapter Failure

The charger adapter and cables can be damaged over time if you always leave your phone to charge overnight. This is usually due to continuous charging and overheating problem.

If you charge when the power is fluctuating, you might get sudden high voltage power which can harm your charger. In the worst-case scenario, this can damage your iPhone’s integrated circuit (IC) chip.

Best Practices For Charging

Charging your iPhone overnight isn’t really recommended. It is better to charge your phone on the go and unplug it whenever it reaches full charge. However, whether you charge your iPhone overnight or not, here are some best practices you can do to conserve your iPhone’s battery life.