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Regenerative Braking Charging Time Estimator

This estimator converts energy recovered through regenerative braking into an equivalent amount of charging time. It is useful for comparing route-level energy recovery with the time a plug-in charger would need to deliver the same usable energy. Transit, delivery, and passenger-vehicle planners can use the result to understand how braking recovery offsets charging demand.

The calculation does not imply that regenerative braking charges the battery at a constant rate. It simply expresses recovered energy as an equivalent charger-time value after charging efficiency.

Inputs

mi
kWh/mi
%
%
kW
%
Result
—
Equivalent plug-in charging time
Trip energy—
Recovered battery energy—
Grid energy equivalent—
Equivalent charging time—

1. Describe the trip
Enter distance and average traction energy consumption.

2. Estimate braking opportunity
Enter the share of trip energy theoretically available from deceleration.

3. Apply recovery efficiency
Use the percentage of braking energy that reaches the battery.

4. Choose a reference charger
Enter charger power and plug-in charging efficiency for the comparison.

5. Read the time equivalent
The result shows how long that charger would need to supply energy equal to the recovered amount.

Recovered energy = Distance × Consumption × Recoverable braking share × Regeneration efficiency
Grid-equivalent energy = Recovered energy ÷ Charging efficiency
Equivalent charging time = Grid-equivalent energy ÷ Charger power

Percentage inputs are converted to decimals. The model assumes the battery can accept all recoverable energy and does not limit regeneration because of state of charge, temperature, or motor power.

What the result means

The primary result is equivalent plug-in charging time based on the values entered above.

Use the result as a scenario estimate. Validate material assumptions with operational data, technical documentation, or qualified advisers as appropriate.

Given:
120 miles, 0.34 kWh/mi, 18% recoverable braking share, 70% regeneration efficiency, 11 kW charger, and 90% plug-in efficiency.

Calculation:
Trip energy = 120 × 0.34 = 40.8 kWh. Recovered energy = 40.8 × 0.18 × 0.70 = 5.14 kWh. Grid-equivalent energy = 5.14 ÷ 0.90 = 5.71 kWh. Time = 5.71 ÷ 11 = 0.519 hours = 31.2 minutes.

Result:
Equivalent charging time: 31.2 minutes.

Interpretation:
The trip’s recovered energy is comparable to roughly half an hour on an 11 kW charger.

Is the result actual time spent regenerating?

No. It is the plug-in charging time needed to deliver an equivalent amount of usable battery energy.

How do I estimate recoverable braking share?

Use route telemetry when available. Urban routes with frequent deceleration usually have a larger recoverable share than steady highway travel.

Can regeneration efficiency be 100%?

The calculator accepts it, but real systems have mechanical, electrical, and battery losses.

Why include plug-in charging efficiency?

It converts battery energy recovered on the road into the grid energy a charger would need to provide for a fair comparison.

What limits real regenerative braking?

A full or cold battery, low traction, low speed, or system power limits may reduce recovery.