C-rate

The C number on a drone or hobby pack is a speed limit, not a capacity. It says how hard you may pull current out relative to the pack’s own rating.

A 1 amp-hour cell run at 2C gives 2 amps and empties in half an hour. It also returns slightly less energy than it would at a gentle pace, because the losses inside become heat.

Cells designed for long runtime are often blocked by a safety circuit from discharging faster than 1C. Cells designed for sudden power, like those in cordless tools, can take up to ten times their own rating.