Why You Shouldn’t Leave Your Phone Charged Overnight

Charging your phone overnight, while convenient, is advised against by experts. Manufacturers like Huawei caution against leaving your phone connected to the charger for extended periods or overnight. The recommendation is to charge your phone during the day, optimizing battery life by avoiding extremes—charging past 70% or dropping below 30%. Apple’s battery optimization kicks in below an 80% charge.

Lithium-ion batteries, which power cellphones, degrade over time due to charge carrier shifts between electrodes. Charging at night results in longer durations, impacting the battery’s total capacity by accumulating a solid electrolytic interface (S.E.I.). To simplify, it’s akin to forcing a saturated sponge to absorb more liquid, causing wear and tear on the battery.

While discharging the battery to 0% may seem unusual, it reduces stress on electrodes, ultimately extending battery life. Safety is another concern; charging your phone at night can lead to thermal runaway, especially if placed under a pillow or on bedding. Paul Shaw from Staffordshire fire rescue warns of the risk of fires due to the phone’s temperature rising unnoticed while you sleep.

Charging habits matter too. It’s advised not to charge your phone for extended periods after reaching full charge. Optimized Battery Charging on iPhones monitors habits, completing the charge after reaching 80%. Balancing total battery longevity with the time between charges is essential.

Samsung suggests using apps to monitor and close background programs, reducing screen brightness, avoiding live backgrounds, setting quicker screen timeouts, and disconnecting from Wi-Fi and Bluetooth when not in use.

While the exact time of day for charging may not be critical, adopting practices to optimize battery usage and avoid safety risks can contribute to longer-lasting and safer phone use.