There are lots of myths about cellphone and the question above represent one of them. Some people think that charging the phone overnight can damage the battery or shortening its lifespan. Is that true? Well, not completely true. The phone is smarter than we think. It has protection mechanism that can stop the current from coming in once it is fully charged. The phone can protect itself from overcharging. So if you undeliberately charge your phone overnight because you fall asleep, the battery is relatively safe.
However, there are some reasons why you can not let such situation happens too often. The ideal spot for Lithium-ion battery is between 50 and 80 percent. It means that the battery life will last longer if you keep your phone charged between that range. On the contrary, leaving your phone fully charged every night may slowly reduce its lifespan.
Lithium-ion batteries are not too friendly with elevated temperatures. The increasing temperature of the battery can cause cell oxidation, which finally affect the capacity and shorten the lifespan. It’s more likely to occur on a device which does not allow heat to escape. To prevent unprecedented overheat, you can take the phone case off if you’re going to leave your phone charged at night.