The C‑rate is a measure of the load or discharge on a battery or accumulator. It is used as an indicator of how fast a battery is being discharged or charged relative to its rated capacity. The C‑rate is calculated by dividing the current flowing into or out of the battery by its rated capacity.

Calculation of the C rate of batteries

C‑rate is an important factor in battery selection and operation because it can affect battery performance, life and safety. Excessive current may cause overheating or damage to the battery. The lower the C‑rate, the better for service life.

The C‑rate is 1C (100 A / 100 Ah) when a battery is discharged with a current of 100 A. If the same battery with a nominal capacity of 100 Ah is discharged with a current of 50 A, the C‑rate is then 0.5C (50 A / 100 Ah).

Importance of C‑rate in the context of battery diagnostics and battery storage monitoring.

How a battery behaves at different C rates can provide valuable information for diagnosing, monitoring, and evaluating first- and second-life batteries. By taking the C‑rate into account in AI-based battery diagnostics, we can draw precise conclusions about the condition and suitability of batteries for specific applications, e.g. in vehicles or in battery storage systems.

  • Checking the internal resistance:
    The internal resistance of a battery affects its performance at different C‑rates. Increased internal resistance can result in voltage drops and reduced performance, especially at high C rates.

  • Checking the State of Health (SoH):
    A battery’s response to different C rates may indicate internal problems such as sulfation, corrosion, or electrochemical changes. A significant difference in battery performance at different C‑rates may be a sign of progressive wear or deterioration of the battery condition.

  • Lifetime forecast:
    The effect of C rates on battery life is well documented. Regular use of high C rates can accelerate aging and shorten battery life. We make forecasts based on different C‑rates for different use cases, so our customers always know how long their storage will last under different conditions.

  • Thermal management:
    High C rates can lead to increased heat generation in the battery. This can be dangerous. However, with NOVUM technology you can prevent. Our Safety Guard does not only react when it detects a temperature increase — by then it is usually already too late — but can already identify modules that will react to certain C rates with increased heat development, so that they can be replaced accordingly and a thermal runaway can be avoided.

  • Battery technology assessment:
    Different battery technologies show different performance profiles at different C‑rates. A battery chemistry that performs better at high C rates may be preferred for rapid discharge applications.

Want to learn more about how NOVUM technology makes batteries predictable? Then get in contact with us. We will be happy to advise you!