What Is the Peukert’s Law Battery Capacity & Run Time Calculator?
Peukert’s Law expresses the non-linear decrease in usable battery capacity as discharge current increases.
How Does the Peukert’s Law Battery Capacity & Run Time Calculator Work?
High current discharge accelerates electrolyte depletion at the electrode surface, triggering early voltage cutoff.
Peukert’s Law Battery Capacity & Run Time Calculator Formula & Variables
The core mathematical equation utilized by this calculator is expressed as:
t = H \left( \frac{C / H}{I} \right)^k, \quad C_{\text{eff}} = I \times t
Peukert equation relating discharge duration to current and exponent k.
How to Use the Peukert’s Law Battery Capacity & Run Time Calculator
- Input manufacturer rated Ah capacity, rated duration hours, actual load current, and Peukert constant k.
Step-by-Step Example Calculation
Lead-Acid Deep Cycle Battery
Input Values:
ratedCapacityAh:100
ratedDischargeHours:20
dischargeCurrentAmps:15
peukertExponentK:1.25
Worked Steps: At 15 A draw, run time is 5.08 hours delivering 76.2 Ah (23.8% capacity penalty).
Understanding Your Result
Outputs expected operating hours before cutoff and effective delivered capacity.
Factors That Affect the Result
- Higher exponent k increases capacity penalty; lithium chemistries have k close to 1.05.
When Should You Use This Calculator?
- Off-grid solar inverter battery bank sizing and emergency backup UPS design.
Assumptions & Limitations
- Assumes constant continuous current at constant temperature.
Frequently Asked Questions
Calculation Accuracy & Reference Note
Standard battery discharge formulation derived by Wilhelm Peukert in 1897.