C-Rate to Current

Formula

Description

The C-rate expresses charge or discharge current relative to the battery capacity. A 1C rate means the current that would fully charge or discharge the battery in exactly 1 hour. For a 3000 mAh battery, 1C = 3 A, 0.5C = 1.5 A (2-hour charge), and 2C = 6 A (30-minute charge). C-rate is the standard way to specify charge and discharge rates across different battery sizes, allowing direct comparison of stress levels. Higher C-rates generate more heat and accelerate degradation.

Variables

• I — Charge or discharge current (A)
• C_rate — C-rate multiplier (dimensionless, e.g., 0.5, 1, 2)
• Q — Battery capacity (Ah)

Practical Notes

Capacity units must be consistent: if Q is in Ah, I will be in A. Common charge rates: standard Li-ion charging is 0.5C-1C; fast charging is 2C-4C; some LFP cells support 5C+ continuous. Discharge ratings: typical Li-ion 1-3C continuous, RC LiPo 25-100C burst. The Peukert effect means actual deliverable capacity decreases at higher C-rates.