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EV & CarsGenerated accuracy model review: 2026-05-06
EV Charging Cost Calculator accuracy and testing
This page documents how Calwarden builds trust for this calculator: source notes, regression-style default tests, limitations, assumptions, unit handling, rounding, and visible change history.
Formula source
- Battery kWh added = battery kWh * (end percent - start percent). Wall kWh = battery kWh added / (1 - charging loss). Cost = wall kWh * price per kWh.
Test cases
Default input regression check
Generated from the checked-in default inputs and calculate function.
Inputs
- EV Model Preset: Tesla Model Y Long Range planning - 75 kWh, 3.8 mi/kWh
- Electricity Rate Preset: U.S. residential average - 16.48¢/kWh
- EV Efficiency Preset: Tesla Model Y Long Range - 3.8 mi/kWh
- Battery Capacity: 75 kWh
- Starting Charge: 20%
- Ending Charge: 90%
- Custom Electricity Price: 0.16 $/kWh
- Charging Loss: 10%
- Custom Vehicle Efficiency: 3.8 mi/kWh
Expected outputs
- Charging Session Cost: $9.61
- Energy from Wall: 58.33 kWh
- Battery Energy Added: 52.5 kWh
- Cost per Mile: $0.05
- Estimated Miles Added: 199.5 mi
Known limitations
- This page documents the checked-in calculator logic and does not certify results for every real-world edge case.
- Use the result as a planning estimate unless the calculator page states a stricter purpose.
Assumptions
- Preset electricity prices and EV efficiencies are checked-in planning snapshots and can become stale.
- Custom electricity price and vehicle efficiency remain editable because utility and charger rates vary.
- Charging loss is modeled as a simple percentage.
- Calculations run locally and are for planning only.
Unit handling
- EV Model Preset accepts one of the configured options.
- Electricity Rate Preset accepts one of the configured options.
- EV Efficiency Preset accepts one of the configured options.
- Battery Capacity accepts values in kWh.
- Starting Charge accepts values in %.
- Ending Charge accepts values in %.
- Custom Electricity Price accepts values in $/kWh.
- Charging Loss accepts values in %.
- Custom Vehicle Efficiency accepts values in mi/kWh.
- Charging Session Cost is displayed as currency.
- Energy from Wall is displayed in kWh.
- Battery Energy Added is displayed in kWh.
- Cost per Mile is displayed as currency.
- Estimated Miles Added is displayed in mi.
Rounding rules
- Number displays use up to 2 decimal places in the calculator UI.
- Currency outputs are displayed with standard US dollar formatting.
- Input precision follows configured step values where provided.
Version history
1.0.0 - 2026-05-06
Generated accuracy and testing page from the current ev-charging-cost-calculator calculator definition.
Change log
2026-05-06
Published default regression test documentation and metadata fallbacks for EV Charging Cost Calculator.
Calculator transparency
Accuracy pages are generated from checked-in calculator definitions and can be upgraded with curated review metadata over time.