Entladerate

Entladerate describes the rate at which a rechargeable energy storage device is discharged, i.e., how quickly energy is removed from the cell, module, or pack. In practice it is usually expressed as a C-rate or as a percentage of nominal capacity per hour. The C-rate is defined as the discharge current I divided by the nominal capacity Cnom: C-rate = I / Cnom. For example, a battery with a nominal capacity of 2 ampere-hours (Ah) drawn at 2 A is discharged at 1C, while a discharge at 1 A corresponds to 0.5C.

Discharge rate affects instantaneous power, usable capacity, and thermal behavior. At higher entladerates, the effective capacity tends to drop due to inefficiencies and internal losses (often described by Peukert's law for certain chemistries), and the battery heats up more. Different chemistries and designs have different recommended maximum continuous and pulse discharge rates; high-drain cells used in electric vehicles and drones are designed for several C, while consumer electronics cells may be specified around 0.5C to 1C. Safety and longevity considerations mean manufacturers often publish discharge rate specifications and recommended operating windows.

Measurement and usage: Entladerate is determined from controlled discharge tests, typically constant-current (CC) discharges followed by capacity measurement. In practice it is important to distinguish discharge rate from charging rate, life cycle expectations, and temperature effects. The term is used across technologies such as lead-acid, nickel-metal hydride, lithium-ion, and solid-state batteries, and it informs design choices for performance, runtime, and thermal management in devices from mobile phones to electric vehicles and energy storage systems.