Regenerative Braking
What happens to kinetic energy during regenerative braking? .
It is converted into electrical energy and stored in the battery.
What are the two main types of braking used in an EV?
Regenerative braking and friction braking.
What is kinetic energy?
The energy an object has because it is moving.
An EV recovers 20% of the energy available during braking. Is this a high or low recovery percentage?
It is a relatively low recovery percentage.
Give one benefit of regenerative braking for a customer.
It can recover energy and increase driving efficiency.
What is the main purpose of regenerative braking?
To recover kinetic energy during deceleration and convert it into electrical energy.
What is the difference between regenerative and friction braking?
Regenerative braking uses the electric motor to slow the vehicle and recover energy; friction braking uses brake pads and discs to create friction.
What does recuperation mean in an EV?
Recovering energy during deceleration or braking and returning it to the battery.
If an EV recovers more energy during braking, what can happen to energy efficiency?
Energy efficiency can improve because less energy is lost as heat.
Why might regenerative braking feel different from braking in a conventional car?
The electric motor helps slow the vehicle, creating a different braking response or feel.
Explain how an electric motor can act as a generator during regenerative braking.
During deceleration, the motor operates as a generator, converting the vehicle's kinetic energy into electrical energy that can be stored in the battery.
What is blended braking?
A system that combines regenerative braking with friction braking to provide the required braking force.
What is one-pedal driving?
A driving mode in which releasing the accelerator produces strong regenerative deceleration, reducing the need to use the brake pedal in many situations.
An EV recovers 30 kWh from braking over one journey and uses 100 kWh of energy. What percentage of the energy used was recovered through braking?
30%
A customer says, “Regenerative braking means I never need the brake pedal.” Is this correct?
No. Friction brakes are still required when stronger braking is needed, during emergencies, or when regenerative braking is limited.
Describe the energy flow during regenerative braking, from the moving vehicle to the battery.
The moving vehicle has kinetic energy. During deceleration, the electric motor acts as a generator and converts kinetic energy into electrical energy, which is then sent to the battery.
Why does an EV use blended braking instead of regenerative braking alone?
Regenerative braking cannot always provide enough braking force, so friction brakes are used when additional braking is required or regeneration is limited.
Explain the difference between kinetic energy, recuperation and blended braking.
Kinetic energy is the energy of motion; recuperation is the recovery of energy during braking; blended braking combines regenerative and friction braking.
An EV normally recovers 75% of available braking energy. On a particular journey, it recovers only 40%. Give two possible reasons.
The battery may be nearly full, the battery may be too cold or too hot, braking may have been too light, or friction braking may have been used more frequently.
A customer complains that regenerative braking is weaker when the battery is almost full. How would you explain this?
The battery has limited capacity to accept more energy when it is nearly full, so regenerative braking may be reduced and the friction brakes may be used more.
Explain why regenerative braking cannot recover 100% of the vehicle's kinetic energy.
Some energy is lost through electrical resistance, motor and inverter losses, battery losses, rolling resistance, aerodynamic drag and friction braking. Therefore, only part of the kinetic energy can be recovered.
During heavy braking, the driver requests maximum braking force. Explain how regenerative and friction braking may work together.
The system initially uses available regenerative braking to recover energy, while friction brakes provide additional braking force when the required deceleration exceeds the regenerative system's capacity. The system continuously balances both systems to maintain safe and stable braking.
Use kinetic energy, recuperation, blended braking and one-pedal driving in one technically accurate explanation.
“During one-pedal driving, releasing the accelerator causes regenerative deceleration. The motor converts the vehicle's kinetic energy into electrical energy through recuperation. During stronger braking, blended braking combines regenerative and friction braking.”
An EV normally recovers 70% of available braking energy. After a fault, recovery falls to 15%. The battery is at 60% SOC and normal temperature. What does this data suggest, and what should the technician investigate?
The low recovery rate suggests a regenerative braking system fault or limitation. The technician should check diagnostic trouble codes, motor/generator operation, inverter operation, battery charging capability, brake-control systems and relevant sensors.
A customer reports: “The car suddenly stopped regenerating and the vehicle feels different when I release the accelerator.” Give two possible causes and describe your diagnostic approach.
Possible causes include a fault in the electric motor, inverter, battery-management system, brake-control system or relevant sensors. The technician should check warning messages and diagnostic trouble codes, compare regenerative braking data with normal values, inspect the relevant electrical and control systems, and perform a controlled road test if safe.