How to use this calculator
- Enter usable capacity when new.
- Add equivalent full cycles and battery age.
- Enter assumed cycling and calendar fade rates.
- Adjust the stress multiplier and calculate.
#1416 · Energy & Environment Tool
Vehicle to Grid Battery Degradation Calculator
Estimate vehicle-to-grid battery capacity degradation from equivalent full cycles, calendar age, assumed fade rates, and an environmental stress multiplier. The model separates cycling and time-related loss and reports remaining capacity plus cumulative energy throughput. It is a planning estimate for comparing scenarios, not a battery health diagnostic or warranty determination.
Calculator
Battery history and assumptionsFormula
Raw fade = (cycles ÷ 100 × cycle fade + age × calendar fade) × stress multiplier
Remaining capacity = New capacity × (1 − capped fade)
Remaining capacity = New capacity × (1 − capped fade)
What the result means
The main result is modeled remaining capacity as a percentage of the new usable capacity. Actual degradation is nonlinear and depends on battery chemistry, temperature, charge windows, power, storage, and management controls.
This intentionally simple scenario model caps estimated loss at 95%. Use measured capacity tests or manufacturer diagnostics for decisions about service or warranty.
Example calculation
At the default 500 equivalent cycles and 4 years, cycling fade and calendar fade are added, adjusted by the stress multiplier, and subtracted from new capacity.
Tips for better results
- Estimate equivalent full cycles from total energy throughput.
- Use lower stress only when storage and temperature are well controlled.
- Avoid treating a short-term range change as permanent degradation.
- Compare the estimate with measured usable energy over several cycles.
Frequently asked questions
What is an equivalent full battery cycle?
It is cumulative discharge equal to 100% of usable capacity; several partial discharges can add up to one equivalent full cycle.
Why are calendar fade and cycle fade separate?
A battery can lose capacity with time even when lightly used, while energy throughput adds a separate cycling contribution.
What does the battery stress multiplier represent?
It adjusts the assumed fade for conditions such as heat, prolonged high state of charge, deep cycling, or high power.
Can this estimate prove a battery warranty claim?
No. Warranty decisions normally require manufacturer-defined tests, thresholds, diagnostics, and documentation.
Why might measured range loss differ from capacity degradation?
Weather, tires, speed, payload, accessory use, and calibration can change range without a permanent capacity change.
Related calculators
Degradation model variables
| Variable | Role |
|---|---|
| Equivalent cycles | Cumulative battery throughput |
| Cycle fade | Assumed loss per 100 cycles |
| Calendar fade | Assumed loss per year |
| Stress multiplier | Scenario adjustment |