Regenerative braking
Using an electric drive motor as a generator during deceleration to convert kinetic energy back into electricity stored in the battery.
In regenerative braking, the inverter reverses torque so the traction motor acts as a generator. Kinetic energy that friction brakes would turn into heat is converted to electricity and returned to the battery. Friction brakes still handle emergency stops, very low speeds and situations where the battery cannot accept charge (full or very cold).
Example: 2,000 kg at 100 km/h (27.8 m/s): E = 0.5 x 2000 x 27.8² ≈ 772 kJ ≈ 0.21 kWh
Recovered ≈ E x η_regen (about 60–70% wheel-to-battery-to-wheel)
The recoverable share depends on drive cycle: in stop-and-go city driving, regeneration can extend range by roughly 10–25%; on steady motorway driving the gain is small because little braking occurs. A long mountain descent can recover substantial energy, offset by the potential energy spent on the climb (2,000 kg x 9.81 m/s² x 1,000 m ≈ 19.6 MJ ≈ 5.4 kWh per 1,000 m of elevation).
Maximum regenerative power is limited by motor rating and battery charge acceptance, commonly 50–250 kW in modern cars. "One-pedal driving" modes use strong regeneration (up to about 0.2–0.3 g) when the accelerator is lifted. Hybrids (HEV, PHEV), electric trains, trams and lifts use the same principle; railways can feed braking energy back into overhead lines or wayside storage.
Related terms
All terms →- Battery electric vehicle (BEV)
A vehicle propelled solely by electric motors powered from an on-board rechargeable battery, with no internal combustion engine.
- EV efficiency (kWh/100 km)
The electrical energy an electric vehicle consumes per distance, usually in kWh/100 km or Wh/km (Europe) or miles/kWh and MPGe (US).
- Plug-in hybrid (PHEV)
A vehicle combining an internal combustion engine with a battery and electric motor that can be charged from the grid, giving a limited all-electric range.
- Fuel cell electric vehicle (FCEV)
An electric vehicle that generates its electricity on board from hydrogen in a fuel cell, emitting only water vapour at the tailpipe.
- Joule (J)
The SI unit of energy, work and heat: the work done by a force of one newton over one metre, or one watt sustained for one second.