Glossary → Battery & Power Terms
What Is a Battery Cycle?
One complete charge-discharge cycle of your phone battery.
Definition: A battery cycle is one complete charge and discharge of a phone battery. Charging from 50% to 100% twice counts as one cycle — not two. Most lithium-ion phone batteries are rated for 300–500 cycles before noticeable capacity loss. Apple rates iPhones to retain 80% capacity at 500 cycles.
How cycles accumulate
A heavy user who charges their phone twice a day may accumulate 700+ cycles per year. A light user charging once daily accumulates around 365. At 500 cycles, most batteries retain roughly 80% capacity — meaning a full charge only lasts 80% as long as it used to. At 700–800 cycles, the phone may shut down randomly at 20–30% remaining as the battery can no longer deliver stable power under load.
How to check cycle count
iPhone: Settings → Privacy → Analytics → Analytics Data → look for files named “log-aggregated” — cycle count is listed as “CycleCount”.
Samsung: Dial *#0228# for a quick battery status check.
All Android: AccuBattery app tracks cycle count and health over time with daily use.
Related terms
→ Battery Health — cycles drive health decline over time
→ Charging Port — port faults can affect how effectively cycles complete
→ Power IC — manages charging and discharging across every cycle
Phone shutting down before 0%?
High cycle count causes random shutdowns under load. PhoneDoctor replaces batteries for all brands — 45 minutes, OEM parts, 90-day warranty.