Electric Bus Battery Degradation Calculator

1. Enter original usable capacity
Use the usable energy available when the battery was new, not necessarily the gross nameplate capacity.

2. Estimate equivalent full cycles
Combine partial cycles into equivalent full cycles; two 50% discharges equal roughly one full cycle.

3. Set the reference cycle-life assumption
Use a chemistry- or fleet-specific value when reliable test or warranty data exists.

4. Add calendar aging
Enter age and an annual fade assumption that reflects storage temperature and state of charge.

5. Review remaining capacity
Compare retained percentage and kilowatt-hours with route, reserve, and replacement requirements.

Cycle fade (%) = Equivalent full cycles ÷ Reference cycle life × Fade at reference life

Calendar fade (%) = Battery age × Annual calendar fade

Remaining capacity = Original capacity × [1 − (Cycle fade + Calendar fade) ÷ 100]

This is a linear scenario model, capped below total failure. It does not model nonlinear aging, cell replacement, software buffers, or interactions between cycling and calendar aging.

What the result means

The result is a scenario estimate of usable energy capacity remaining after the entered cycle and calendar fade.

Use battery-management data, controlled capacity tests, and manufacturer guidance for operational or replacement decisions.

Given: original usable capacity of 350 kWh, 2200 equivalent full cycles, a 4000-cycle reference life with 20% fade, and 4 years at 1.8% calendar fade per year.

Calculation: Cycle fade = 2200 ÷ 4000 × 20%. Calendar fade = 4 × 1.8%. Remaining capacity = 350 × [1 − total fade ÷ 100].

Result: The calculator reports estimated remaining usable capacity and the portion lost under this simplified scenario.