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Home EV Charger Range Loss Estimator

The Home EV Charger Range Loss Estimator estimates how much driving range is available between a starting and ending battery charge, after holding back a selected reserve. It converts usable battery energy into miles using the vehicle’s energy consumption rate.

The tool helps drivers plan daily charging limits, commuting windows, and a practical buffer for weather or unexpected travel. It is an estimate rather than a route forecast: speed, temperature, elevation, wind, tires, cabin climate, and battery condition all influence real-world efficiency.

Trip energy assumptions

kWh
%
%
kWh/100 mi
%
Result
—
Estimated usable driving range
Battery energy between SOC limits—
Range before reserve—
Range held as reserve—

1. Enter usable battery capacity
Use the battery energy available to the driver rather than gross pack capacity when known.

2. Set starting and ending charge
Define the charge window you expect to use before the next charging session.

3. Enter driving efficiency
Use a recent or expected consumption rate in kWh per 100 miles.

4. Choose a reserve
Hold back a percentage of the calculated range for uncertainty or emergencies.

5. Review usable range
Compare the reserve-adjusted miles with your planned trip distance.

Energy in charge window = Battery capacity × (Starting SOC − Ending SOC) Range before reserve = Energy in charge window ÷ (kWh per 100 miles) × 100 Usable range = Range before reserve × (1 − Reserve fraction)

The model assumes the entered efficiency remains constant throughout the trip.

What the result means

Usable range is the estimated distance available within the selected charge window after preserving the chosen buffer.

Cold weather, high speed, towing, elevation, and HVAC use can reduce actual range.

Given: 75 kWh usable battery, 80% starting charge, 30% ending charge, 30 kWh/100 mi efficiency, and 10% reserve.

Calculation: Energy = 75 × 0.50 = 37.5 kWh. Range before reserve = 37.5 ÷ 30 × 100 = 125 miles. Usable range = 125 × 0.90 = 112.5 miles.

Result: Estimated usable driving range is 112.5 miles.

What does kWh per 100 miles mean?

It is the battery energy used to travel 100 miles. A lower value indicates better efficiency.

Why include both an ending charge and a reserve?

Ending charge defines the planned battery floor. The reserve adds a further planning buffer to the resulting distance.

Can I use miles per kWh instead?

Convert it first: kWh per 100 miles = 100 ÷ miles per kWh.

How should winter driving be handled?

Use a higher consumption value based on cold-weather experience or a conservative estimate.

Is this the same as the vehicle’s displayed range?

No. The displayed range may use recent driving, weather, route, and vehicle-specific prediction methods.