Does charging your phone overnight harm battery health?

Manufacturers such as Apple and Samsung confirm that their phones stop charging once the battery reaches full capacity, thanks to protective chips and smart charging software.

Older models may continue drawing small amounts of power to maintain a full charge, a process known as "trickle charging", which can gradually degrade battery life, according to PCMag. To counter this, newer devices feature optimized charging systems.

Apple’s Optimized Battery Charging, for example, learns a user’s daily routine and delays full charging until just before the phone is typically used. As the battery approaches 100%, the charging current is gradually reduced to limit heat buildup, a key factor in battery wear.

A smartphone is charging. Photo courtesy of Anker

While overcharging is no longer a concern for most devices, experts advise against keeping your battery at 100% for extended periods.

Lithium-ion batteries last longest when kept between 20% and 80% charge, according to Android Authority. Instead of waiting for your phone to hit 0%, it is better to top it up regularly and avoid fully charging it throughout the day.

If you charge your phone at night, consider unplugging it when you wake up or using a smart plug that shuts off automatically.

Users are also advised not to cover charging phones with books, other devices, or bedding, as trapped heat can damage the battery. Avoid placing your phone under a pillow, and limit wireless charging, which tends to generate more heat than wired charging.

Another precaution is to use only certified charging cables and adapters. Uncertified accessories may not meet safety standards and can cause overheating or reduced charging efficiency. If your battery performance drops, replacing it is often a cost-effective solution. Most replacements cost between US$40 and $100, depending on the brand, significantly cheaper than purchasing a new device.