EV Battery Battery Degradation Calculator

1. Enter the original specifications
Use the battery capacity and rated range when the vehicle was new.

2. Add age and annual mileage
Enter years in service and a representative annual driving distance.

3. Describe charging stress
Estimate the share of charging done on DC fast chargers and select a stress multiplier for climate and charging habits.

4. Review the capacity estimate
The headline shows estimated remaining capacity as a percentage of the original battery.

5. Compare scenarios
Change one assumption at a time to see which usage pattern has the largest modeled effect.

Degradation % = (1.5 × age + 0.35 × lifetime miles / 10,000 + 0.45 × age × fast-charge share) × stress factor Remaining capacity = original capacity × (1 − degradation / 100)

Age is measured in years, lifetime miles equals age multiplied by annual miles, and fast-charge share is entered as a decimal in the calculation. The result is capped at 45% degradation to keep the planning model within a practical range.

What the result means

The result is an estimate of usable capacity remaining compared with the battery when new. A value of 91% means the model assumes about 9% capacity loss.

Actual degradation depends on battery chemistry, thermal management, storage state of charge, software limits, and measured battery health.

Given: 75 kWh battery, 300-mile original range, 4 years old, 12,000 miles per year, 20% fast charging, and a 1.0 stress factor.

Calculation: Lifetime miles = 4 × 12,000 = 48,000 miles. Degradation = (1.5 × 4 + 0.35 × 4.8 + 0.45 × 4 × 0.20) × 1.0 = 8.04%. Remaining capacity = 75 × (1 − 0.0804) = 68.97 kWh.

Result: About 92.0% capacity remains, supporting an estimated 276 miles under equivalent test conditions.