The old advice to let your phone drain to zero before charging is a relic from the nickel-cadmium battery era and actively damages modern lithium-ion cells. Today's batteries experience the most stress at the extremes — below 20 percent and above 80 percent. The optimal strategy is to keep your phone between 20 and 80 percent most of the time. Plug in when you drop to 20, unplug around 80. This "shallow cycling" reduces chemical degradation and can extend your battery's useful life by one to two years.

Heat is the number one enemy of lithium-ion batteries, more damaging than any charging habit. Charging your phone while it sits on a soft surface like a bed or couch traps heat and can raise the battery temperature into the accelerated degradation zone. Always charge on a hard, flat surface with good airflow. Remove thick cases during extended charging sessions. And never leave your phone on a car dashboard in direct sunlight — a single afternoon of extreme heat can permanently reduce battery capacity by several percent.

Overnight charging is not the battery killer that many articles claim, thanks to modern charge management chips that trickle-charge once the battery reaches full capacity. However, the combination of overnight charging and a thick case in a warm bedroom does create sustained elevated temperatures. If you charge overnight, remove your case, use a standard 5-watt charger instead of a fast charger, and keep your bedroom cool. The slower charge rate generates significantly less heat.

Fast charging is convenient but comes at a cost. The higher current generates more heat and pushes lithium ions into the anode at a rate that causes slight structural damage with each cycle. Reserve fast charging for situations where you genuinely need a quick top-up and use standard charging speed for everyday use. Think of fast charging like sprinting — useful in short bursts but not something you want to do every day if longevity is the goal.