In one line
Ratio of battery power output to energy capacity; a 1C rate fully discharges a battery in one hour.
What it means
C-rate expresses battery power as a ratio of energy capacity. A 100 kWh battery discharging at 1C delivers 100 kW for one hour; at 0.5C it delivers 50 kW for two hours. Utility-scale BESS commonly specifies 0.25C (4-hour) or 0.5C (2-hour); high-power applications (grid frequency response, fast EV charging) use 1C–4C. Higher C-rates accelerate cell aging and reduce round-trip efficiency.
Related terms
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