It’s bedtime. You set your alarm, notice your phone is down to 23% battery, plug it in beside the bed and go to sleep. By the morning, it’s been connected to the charger for some seven to eight hours – much longer than it needed to reach 100%, especially if it’s on a fast charger.

You may have a vague recollection this could be bad for your phone’s battery. The chemistry that makes lithium-ion batteries rechargeable has a limited shelf life, and it’s shortened by repeated charge–discharge cycles.

In the past, the advice has been simple: don’t leave your phone charging overnight and avoid bringing the battery up to 100% to preserve its lifespan, ideally keeping it between 20% and 80%.

In principle, that advice is still sound because the fundamental chemistry of the battery inside your phone hasn’t changed. Regularly draining it to 0% and then filling it up to 100% will shorten its lifespan.

However, modern phones have improved battery health management and charging controls. As a result, the answer to whether it’s okay to leave your phone plugged in overnight has become more nuanced in recent years.

Better charging controls

Rather than simply telling people not to charge overnight, modern........

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