Charging to 100% Stresses Lithium-ion Batteries, Which Is Why Apple, Google, and Samsung Cap Charging at 80% to Extend Lifespan

ZD Net fact-checked six common smartphone battery myths against manufacturer documentation and peer-reviewed research, finding most advice is outdated from the nickel-cadmium era. Charging to 100% stresses lithium-ion batteries, which is why Apple, Google, and Samsung cap charging at 80% to extend lifespan. Draining to 0% to 'calibrate' is unnecessary; lithium-ion batteries lack the memory effect of older nickel-based cells, though Google notes Pixel devices need a full charge every 10th cycle for accurate wear reporting.

Leaving a phone plugged in overnight does not overcharge or destroy the battery, as modern chargers and phones have safeguards, despite an undated Samsung page advising unplugging at 100% to avoid swelling. Charging in extreme cold or heat is harmful: below 0°C (32°F), lithium plating permanently damages the battery, and heat is a major concern for all manufacturers. is designed to reduce the wear on your battery and improve its lifespan by reducing the time your iPhone spends fully charged.