Battery Capacity for Sequential Events

How to Use This Calculator

This calculator determines the total required battery capacity (C) in ampere-hours (Ah) for two sequential discharge events. It accounts for the load currents (I1, I2), discharge times (t1, t2), discharge rates (Rc1, Rc2), and includes corrections for non-linear effects in internal resistance at low states of charge (SoC).

To use this calculator:

1. Enter the load current (I1) and discharge time (t1) for the first event.
2. Enter the load current (I2) and discharge time (t2) for the second event.
3. Enter the discharge rates (Rc1, Rc2) as fractions of the nominal capacity.
4. Select the battery chemistry from the dropdown menu. Different chemistries have different base and enhanced Peukert exponents (k_base, k_enhanced).
5. Enter the current correction factor (CI) to adjust for experimental discrepancies. Default is 0.1 (10%).
6. Enter the SoC threshold (%) for non-linear effects. Default is 40%.
7. Click "Calculate" to determine the total required battery capacity.

The formula used to calculate the battery capacity is:

C = C1 + C2

Where:

• C1: Capacity consumed during the first event, calculated as I1 * t1 * min(Rc1, 1.2)^(1-k1) * (1 + CI).
• C2: Capacity consumed during the second event, calculated as I2 * t2 * min(Rc2, 1.2)^(1-k2) * (1 + CI).
• k1, k2: Peukert exponents (base or enhanced, depending on SoC).
• CI: Current correction factor (default = 0.1 or 10%).
• SoC Threshold: State of charge (%) below which non-linear effects occur.

Note: Rc is clamped at 1.2C for discharge rates above 1.2C. The Peukert exponent switches to an enhanced value below the SoC threshold to account for increased internal resistance.