Fast Charging
Fast charging is any method that delivers more power to a battery than a basic charger, so it fills in less time.
On this page 3 sections
Fast charging is any charging method that delivers more power to a battery than a basic charger does, so the battery fills in less time. Power is measured in watts (W). A higher figure means more power at the peak.
How it works
Power is volts multiplied by amps. Fast charging raises one or both, and the device and charger talk to each other to agree on a safe level. Brands use different methods. A common open standard, USB Power Delivery, lets chargers and devices from different makers agree on power. The cable also matters, because a thin or low-grade cable limits how much current can flow.
The charging curve
A battery takes power fastest when it is nearly empty. As it fills, the device lowers the power to protect the battery, so the final stretch is slower. Claims such as 50 per cent in 20 minutes describe this early, fastest stage.
What it does not promise
The watt figure is a peak, not an average. It is reached only when the device, cable and charger all support it, and the slowest part sets the speed. Fast charging produces more heat, and heat shortens battery life over the years, which is why devices manage it carefully.