What is the Peukert Effect?

The Peukert effect describes how a batteries capacity is directly affected by the speed at which it is discharged. The Peukert value is directly related to the internal resistance of the battery. The higher the internal resistance, the higher the losses while charging and discharging, especially at higher currents. This means that the faster a battery is discharged, the lower its ampere hour capacity. Conversely, if it is drained slower, the AH capacity is higher. This is why – when comparing batteries – the ampere hour rate is taken into consideration when looking at the batteries rating. Some suppliers rate their batteries at the 100 hour rate, some at the 20 hour rate, and some at a 10, 8, 6 or 5 hour rate. “See What should I look for when buying deep cycle batteries?”

Battery Council International gives the following table for assistants in comparing batteries rated at various Amp Hour rates and times.

    * 20 hour 125%
    * 6 hour 100%
    * 5 hour 95%
    * 4 hour 89%
    * 3 hour 82%
    * 2 hour 72%
    * 1 hour 55%