Phone battery health: the habits that matter and the ones that don't
Heat does more damage than charging overnight. A short guide to what actually wears out a lithium-ion battery.
Phone batteries are lithium-ion cells, and every one of them loses capacity with age. You cannot stop that. You can slow it down, and a few of the popular rules matter far less than people think.
Heat is the main enemy#
High temperature ages a battery faster than almost anything else you do to it. A phone left on a car dashboard, charged under a pillow or used for navigation in direct sun runs hot. Take the case off if the phone is warm while charging, and keep it out of closed cars in summer.
Staying at full charge for hours#
Holding a battery at 100 percent for long stretches puts stress on it. This is why many current phones offer an optimised or limited charging setting that learns your routine, or caps charge at around 80 percent. If your phone has one, turning it on costs you a little capacity per day and is worth it if you keep phones for several years.
Overnight charging is not the villain#
Modern phones stop drawing power when full, so overnight charging does not "overcharge" the cell. The concern is the hours sitting at 100 percent while warm, which the optimised-charging feature handles.
The rules to relax about#
Letting it hit zero. Deep discharges are harder on a battery than shallow ones, but occasional low points are not a problem.
Fast chargers. Phones negotiate charging speed and manage heat. A certified charger from a reputable maker is fine.
Closing apps constantly. Forcing apps shut usually costs more battery in restarts than it saves.
Check your battery's state#
Both major phone platforms show a battery health or capacity figure in the settings. When it drops well below where it started, replacing the battery is often cheaper than replacing the phone. Use the maker's service or a repairer that uses quality parts, and get a quote first.
Our short version#
Keep it cool, avoid long stretches at 100 percent if your phone can manage that for you, use a certified charger, and ignore most of the rest. Your battery will still age, but you will stretch the useful life by a good margin.