C rating

The C rating is a multiplier that, combined with a pack's capacity, gives a theoretical maximum continuous discharge current. A 1500 mAh pack rated at 75C is claimed to handle roughly 112.5 amps continuously, at least on paper. Pilots use the C rating to judge whether a pack can keep up with the current draw of a given motor and propeller combination.

In practice, C ratings are one of the least standardized numbers on a battery label. Different brands measure and market the figure differently, and voltage sag under load is often a better real-world indicator of a pack's quality than the printed C rating. Two packs with the same claimed rating can behave very differently once they are actually pulling current mid-flight.

A frequent beginner mistake is choosing a battery purely by comparing C rating numbers between brands as if they were directly comparable. It is more useful to match pack size and cell count to what the frame and motors are designed for, then judge real performance by how much the voltage sags during a hard punch-out, rather than trusting the printed rating alone.