Does 100% Charge Kill Your iPhone Battery?

Is charging your iPhone to 100% actually destroying your battery? The short answer is no, but leaving it plugged in overnight definitely is. Reaching 100% isn't the villain here. The real damage happens when your phone sits at full charge for hours under chemical stress. Your iPhone battery is designed to handle 500 to 1,000 charge cycles before dropping below 80% health. That is about three to five years of normal use. But heat is the real enemy. Charging in direct sunlight or playing heavy games while plugged in degrades lithium-ion cells fast. Turn on Optimized Battery Charging, keep your phone cool, and stop worrying about every percentage point.