What is the 80/20 rule for charging?

The 80/20 charging rule is an optimization strategy to extend the lifespan of lithium batteries. It recommends setting the upper charging limit of a device at 80% to avoid the battery being in a high-voltage state for prolonged periods. Maintaining the charge level at 80% can reduce chemical stress by approximately 20%-30% and lower temperature rise by 2-5℃, thereby significantly delaying battery aging. For instance, compatible iPad and iPhone models can activate the "80% limit" option in system settings, where charging pauses at 80% and only resumes when the level drops to 75%. Test data indicates that iPhone 15 Pro Max units using this strategy retain 94% battery health after one year - 7% higher than conventional charging. Note that this rule should be combined with avoiding deep discharges (below 20%), with the optimal charge range maintained between 30%-80%. Additionally, using original chargers and avoiding high-temperature environments is recommended for optimal battery preservation.