Electric, Hybrid and Fuel-Cell Vehicles

Introduction

Road transport is undergoing a major powertrain transition. Conventional vehicles convert the chemical energy of petrol or diesel into mechanical work through combustion. Electrified vehicles instead use one or more electric machines, power-electronic converters, electrochemical energy stores, or hydrogen fuel cells. The transition is driven by requirements for lower greenhouse-gas emissions, improved urban air quality, energy diversification, and increasingly stringent efficiency and safety regulations.

Electrification does not describe one single vehicle design. A mild hybrid, a plug-in hybrid, a battery-electric vehicle (BEV), and a fuel-cell electric vehicle (FCEV) have different energy paths, component requirements, control strategies, costs, and environmental profiles. Automotive technicians and engineers must therefore understand both the common electrical principles and the architectural differences.

This chapter examines electrified powertrains from energy conversion to vehicle operation. It explains traction motors, inverters, batteries, battery-management systems, charging, regenerative braking, high-voltage safety, thermal management, fuel cells, lifecycle performance, and professional diagnostic practice.

Learning Objectives

By the end of this chapter, students should be able to:

1. Compare the architectures and applications of mild hybrids, full hybrids, plug-in hybrids, BEVs, and FCEVs.
2. Explain how traction motors, inverters, batteries, fuel cells, and control systems interact.
3. Apply fundamental power, energy, efficiency, and battery-sizing relationships.
4. Describe battery-management, charging, regenerative-braking, and thermal-management strategies.
5. Apply safe procedures when inspecting or servicing high-voltage vehicles.
6. Evaluate electrified vehicles using technical, economic, environmental, and lifecycle criteria.

1. Energy and Power in an Electrified Vehicle

Two concepts must be distinguished. Power is the rate at which energy is transferred and is measured in watts (W) or kilowatts (kW). It determines acceleration capability, grade-climbing ability, and charging rate. Energy is the quantity stored or consumed and is measured in joules (J) or kilowatt-hours (kWh). It determines driving range or fuel endurance.

The instantaneous mechanical power at the wheels is:

where P_w is wheel power in watts, F_w is tractive force in newtons, and v is vehicle speed in metres per second. This relationship assumes the force and speed are measured at the same point in the direction of motion. If rotational speed and torque are used instead:

where T is torque in newton-metres and ω is angular speed in radians per second. Since a radian is dimensionless, the units are N·m/s, equivalent to W.

The main resistive forces are aerodynamic drag, rolling resistance, and road-gradient force. A useful longitudinal model is:

Here, m is vehicle mass, a acceleration, C_rr rolling-resistance coefficient, g gravitational acceleration, θ road angle, ρ air density, C_d drag coefficient, and A frontal area. The expression assumes a rigid vehicle, steady local air conditions, and forces resolved along the road. Driveline losses must be added when estimating motor or battery power.

If total discharge efficiency from battery to wheels is η_d, battery power is approximately:

During regenerative braking, energy flows in the opposite direction, but charging, inverter, motor, and battery losses mean that not all wheel energy is recovered.

Energy architectures

A vehicle may contain several energy-conversion stages:

Figure: Simplified forward and regenerative energy paths in electrified powertrains.

2. Electrified Powertrain Architectures

Mild hybrid electric vehicle

A mild hybrid commonly uses a 48 V electrical system, an integrated starter-generator, and a relatively small battery. It can recover braking energy, restart the engine smoothly, support accessories, and provide torque assistance. It normally cannot propel the vehicle for sustained operation using electric power alone. Its advantages are modest cost and packaging complexity; its limitations are limited electric-only operation and continued dependence on fuel combustion.

Full hybrid electric vehicle

A full hybrid can propel the vehicle electrically for short periods, operate the engine alone, or combine engine and motor power. A planetary power-split transmission is one important implementation, although parallel and series layouts are also used. The battery is generally charged by regenerative braking and engine-generated electrical power rather than by an external plug.

In a parallel hybrid, engine and motor torque can both reach the wheels mechanically. In a series hybrid, the engine drives a generator and the wheels are driven electrically. A power-split hybrid combines mechanical and electrical paths and can vary engine operating conditions over a wide range.

Plug-in hybrid electric vehicle

A PHEV has a larger battery and an external charging connection. It can complete many daily journeys electrically, while the combustion engine supplies extended range or high-power operation. PHEVs offer flexibility but have two propulsion systems, increasing mass, cost, maintenance complexity, and control-system requirements. Their real-world emissions depend strongly on charging frequency and usage.

Battery-electric vehicle

A BEV stores propulsion energy in a high-voltage battery. Its principal components are the battery pack, contactors, pre-charge circuit, inverter, motor, reduction gear, onboard charger, DC fast-charge interface, and low-voltage auxiliary system. There is no tailpipe emission during operation, and the drivetrain has relatively few moving parts. Range, charging time, battery cost, cold-weather performance, and charging access remain important considerations.

Fuel-cell electric vehicle

An FCEV uses hydrogen in a fuel-cell stack to produce electricity electrochemically. A small battery or supercapacitor handles transient power and regenerative braking, while the fuel cell supplies average energy. Hydrogen is stored in high-pressure tanks. FCEVs can be refuelled rapidly and are attractive for some long-distance or high-utilization applications, but they require hydrogen infrastructure and involve energy losses in hydrogen production, compression, distribution, and conversion.

3. Traction Motors and Inverters

An electric motor converts electrical power into torque and, during regenerative braking, converts mechanical power back into electrical power. Common automotive machines include permanent-magnet synchronous motors (PMSMs), induction motors, and electrically excited synchronous motors.

A PMSM offers high power density and efficiency, but permanent magnets may increase cost and create dependence on critical materials. An induction motor has no rotor magnets and is robust, but its efficiency and inverter requirements vary with operating point. Electrically excited machines permit control of rotor magnetic field and can reduce magnet dependence, although they require additional excitation hardware.

Motor speed and torque are controlled by a power inverter. The battery supplies direct current (DC), whereas most traction motors use three-phase alternating current (AC). Semiconductor switches, commonly insulated-gate bipolar transistors or silicon-carbide MOSFETs, create controlled phase currents through pulse-width modulation. The inverter also rectifies generated power during regenerative braking.

A simplified motor efficiency is:

where η_m is efficiency, P_mech is mechanical output power, and P_elec is electrical input power. Efficiency is not constant: it changes with speed, torque, temperature, switching frequency, and control strategy. The motor must therefore be selected using an efficiency map rather than a single peak-efficiency value.

The motor controller receives accelerator, brake, speed, temperature, battery, and stability-control information. It calculates requested torque, limits it according to battery power and thermal conditions, and coordinates friction braking with regenerative braking.

4. Battery Technology and Battery Management

Most modern automotive traction batteries use lithium-ion cells. A cell has an anode, cathode, electrolyte, separator, current collectors, and a protective enclosure. Cells are connected in series to increase voltage and in parallel to increase capacity and current capability. A module groups cells, and a pack integrates modules, busbars, sensors, cooling, contactors, structural elements, and safety devices.

For an ideal series string of N_s cells, nominal pack voltage is:

For N_p parallel strings, ideal capacity is:

The stored electrical energy is approximately:

when voltage is in volts and capacity is in ampere-hours, producing watt-hours. Real usable energy is lower because voltage varies with state of charge, current, temperature, ageing, and the permitted operating window.

State of charge (SOC) expresses remaining usable charge. A simplified coulomb-counting estimate is:

where Q_n is nominal charge capacity and I is battery current, defined positive for discharge in this expression. Practical systems correct coulomb counting using voltage, current, temperature, and electrochemical models because sensor offset causes cumulative error.

State of health (SOH) describes degradation relative to a reference condition. It may be based on remaining capacity, increased internal resistance, power capability, or a combination. Depth of discharge (DOD) is the fraction of capacity removed from a fully charged reference state. Limiting extreme SOC, high temperature, and high current generally reduces degradation, although exact ageing depends on chemistry and duty cycle.

The battery-management system (BMS) performs several functions:

• measures cell voltage, pack current, and temperatures;
• estimates SOC, SOH, and available charge/discharge power;
• balances cell voltages;
• controls contactors and pre-charge;
• detects overvoltage, undervoltage, overcurrent, insulation faults, and overheating;
• communicates limits to the vehicle controller and charger;
• records diagnostic data and fault events.

Passive balancing dissipates energy from higher-voltage cells through resistors. Active balancing transfers energy between cells and may improve efficiency, but adds cost and complexity. Cell monitoring is essential because a series-connected pack is limited by its weakest or most highly stressed cell.

5. Charging Systems

AC charging supplies alternating current to the vehicle’s onboard charger, which converts it to controlled DC for the battery. Charging power is approximately:

where V_AC and I_AC are charging voltage and current, and η_ch is charger efficiency. The vehicle, circuit, connector, and installation must all be rated for the selected current.

DC fast charging bypasses the onboard AC charger. An external charging station converts grid AC to regulated DC and communicates with the BMS. High charging power reduces time but increases thermal load, infrastructure demand, and potentially battery degradation. Charging typically tapers at high SOC because the battery-management system reduces current to control cell voltage and temperature.

Charging is governed by communication between vehicle and equipment. Systems include protective earth, residual-current protection, connector interlocks, insulation monitoring, and contactor control. Charging equipment must comply with the applicable national and regional standards; technicians should never bypass interlocks or use damaged connectors.

6. Regenerative Braking and Vehicle Control

During deceleration, the traction motor operates as a generator. The inverter directs generated electrical power to the battery, subject to limits imposed by battery SOC, temperature, cell voltage, motor speed, and traction conditions. Friction brakes supply the remaining braking torque and provide braking when the battery cannot accept energy.

The total requested braking force can be represented conceptually as:

This is a control allocation, not a claim that both forces are always available at their maximum. The controller prioritizes stable deceleration, axle-load distribution, anti-lock braking, battery protection, and driver-pedal response.

At low speed, regenerative torque may fall because motor back electromotive force and controllability decrease. On slippery roads, regenerative braking must be reduced to avoid wheel slip. Blended braking therefore requires accurate speed sensors, rapid communication, and carefully calibrated pedal mapping.

Recovered energy is approximately:

where η_total includes motor, inverter, wiring, battery-charge, and other efficiencies. For a vehicle of mass m changing speed from v₁ to v₂, the kinetic-energy change is:

This applies when speed is expressed in m/s and excludes road-gradient and aerodynamic effects during the event.

7. High-Voltage Safety and Service Practice

Automotive high-voltage systems may present lethal shock, arc-flash, fire, and unexpected vehicle-movement hazards. Orange cables commonly identify high-voltage circuits, but colour alone is not a sufficient safety test.

A professional isolation procedure normally includes:

1. consult the manufacturer’s service information and risk assessment;
2. secure the vehicle, remove the key or disable the authorized access device;
3. wear specified arc-rated and electrically rated PPE;
4. identify the service disconnect and isolate the high-voltage source;
5. wait the specified discharge time for capacitors;
6. verify absence of voltage using an approved, correctly rated meter;
7. prevent re-energization with lockout/tagout;
8. re-test the instrument on a known source where required by procedure;
9. inspect for damage, insulation failure, electrolyte leakage, or thermal events.

The “test before touch” principle is essential. A battery pack can remain hazardous even when the vehicle is switched off, and a damaged vehicle may contain isolated but unstable cells. Water immersion, collision damage, or thermal runaway requires emergency and manufacturer-specific procedures. Only trained personnel with appropriate certification should open packs or work on exposed high-voltage conductors.

8. Thermal Management

Electrified powertrain performance is temperature-dependent. Batteries deliver less power at low temperature, while high temperature accelerates ageing and can increase safety risk. Motors, inverters, onboard chargers, and fuel-cell stacks also produce heat.

Battery heat generation is often approximated by:

where I is current, R is effective internal resistance, and P_side represents additional electrochemical and parasitic heat sources. The expression is a simplified engineering approximation; resistance varies with SOC, temperature, current, and ageing.

Cooling may use air, liquid plates, refrigerant circuits, heat pumps, or combinations. Thermal-management goals include temperature uniformity, acceptable peak temperature, rapid warm-up when needed, and isolation between damaged components. A BMS limits power and charging when thermal conditions exceed calibrated boundaries.

Heat pumps can use waste heat or ambient heat to warm the cabin and battery more efficiently than resistive heaters, particularly in cold climates. However, their performance declines at very low ambient temperature and depends on system design.

9. Fuel-Cell Electric Vehicles

A proton-exchange-membrane fuel cell combines hydrogen and oxygen to produce electricity, water, and heat. Hydrogen is oxidized at the anode, protons pass through the membrane, and electrons travel through the external circuit. Oxygen is reduced at the cathode. The overall ideal reaction is:

A fuel-cell stack contains many cells connected electrically. The stack requires hydrogen delivery, air compression, humidification or water management, cooling, power conditioning, and control. A buffer battery absorbs regenerative energy and supplies peak acceleration power, allowing the fuel cell to operate closer to efficient operating regions.

Fuel-cell efficiency can be expressed as:

where P_electric is electrical output, ṁ_H2 is hydrogen mass-flow rate, and LHV is hydrogen’s lower heating value. This is a system boundary calculation; compressor, pump, cooling, and power-conditioning loads must be included when calculating net efficiency.

FCEVs produce no tailpipe carbon dioxide during operation, but lifecycle emissions depend on hydrogen production. Hydrogen made from renewable electricity can have low operational emissions, whereas hydrogen made from fossil natural gas without carbon capture may have substantial upstream emissions.

10. Lifecycle Performance and Sustainability

Tailpipe emissions alone are insufficient for comparing powertrains. A lifecycle assessment considers raw-material extraction, component manufacture, energy production, vehicle use, maintenance, recycling, and end-of-life treatment.

A simplified lifecycle greenhouse-gas model is:

The result depends on the functional unit, geographic electricity mix, annual distance, vehicle lifetime, battery replacement, manufacturing energy, and recycling assumptions. This is a boundary-dependent accounting model, not a universal constant.

BEVs generally have higher manufacturing emissions than comparable combustion vehicles because of battery production, but may have lower use-phase emissions and higher drivetrain efficiency. The balance improves as electricity becomes less carbon-intensive and vehicle service life increases. Hybrid vehicles can reduce fuel consumption, especially in urban operation. FCEVs require evaluation of hydrogen production and distribution, not merely the absence of tailpipe pollutants.

Critical materials, labour conditions, water use, recycling infrastructure, and supply-chain transparency are ethical as well as technical concerns. Battery recycling can recover valuable materials and reduce future extraction demand, but collection, transport, chemistry diversity, and safe disassembly remain challenges.

11. Illustrative Case: Selecting a Fleet Powertrain

Background. A delivery company operates 60 vans. Each van travels 160 km per day, returns to a depot overnight, and spends much of its time in urban stop-and-go traffic. The company is considering diesel, PHEV, BEV, and FCEV options.

Problem. Management wants lower operating emissions and predictable availability but is concerned about charging infrastructure, winter range, and capital cost.

Analysis. The fixed depot location makes overnight charging practical. Stop-and-go operation creates frequent opportunities for regenerative braking, while daily distance is within the potential range of many BEVs. A fleet energy audit should measure payload, speed, ambient temperature, auxiliary loads, and route elevation rather than relying solely on laboratory ratings. Peak depot demand must be calculated from charger power, diversity, and operating schedules. For example, 60 chargers each rated at 11 kW would imply a theoretical simultaneous demand of 660 kW before diversity and site losses; smart charging could reduce the peak by staggering charge periods.

Approach. The company installs a pilot of six BEVs, six PHEVs, and a telematics system. It records energy per kilometre, charging completion, downtime, battery temperature, and driver feedback. A depot electrical study identifies transformer capacity and protection requirements. Vehicles are charged mainly during low-demand periods, with a reserve SOC policy for unexpected route changes.

Outcome. In this illustrative case, BEVs provide the lowest routine energy cost and the simplest urban operation, while PHEVs provide operational resilience on exceptional long routes. FCEVs are rejected for this depot because hydrogen supply is unavailable and the route profile does not justify its infrastructure. The final decision is not based on vehicle price alone; it includes charger installation, maintenance, energy tariffs, residual value, training, and lifecycle emissions.

Learning points. Fleet selection must match duty cycle and infrastructure. Demonstration data are more valuable than assumptions about average drivers. Charging management is part of the powertrain system, and safety training must be implemented before vehicle deployment.

12. Diagnostics, Data, and Contemporary Developments

Electrified vehicles require technicians to combine mechanical, electrical, electronic, and software skills. Diagnostic data may include isolation resistance, cell-voltage spread, temperature gradients, contactor states, inverter faults, charging history, and estimated battery power capability. A fault code identifies a monitored abnormality, not necessarily the failed component. Testing must follow a decision tree based on wiring diagrams, measured values, and manufacturer procedures.

Artificial intelligence and machine learning are increasingly used for predictive maintenance, battery state estimation, anomaly detection, route-energy prediction, and charging optimization. These systems are useful only when sensor data are reliable and models are validated across temperature, ageing, driving style, and vehicle variants. A model should not override safety interlocks or replace a qualified technician’s isolation procedure.

Contemporary development areas include silicon-carbide inverters, higher-voltage platforms, fast-charging architectures, structural battery packs, solid-state battery research, bidirectional charging, vehicle-to-home and vehicle-to-grid operation, improved recycling, and hydrogen systems for heavy transport. Each development involves trade-offs in cost, reliability, standardization, serviceability, and safety. A claimed improvement in energy density or charging speed must be evaluated with its test conditions and system boundary.

Challenges and Limitations

Electrified powertrains do not eliminate engineering problems; they relocate and transform them. Battery mass affects tyres, suspension, crash structures, and road energy consumption. Fast charging demands high-power infrastructure. Cold climates reduce available energy and increase heating demand. Battery ageing is difficult to predict because it depends on usage history. Hybrid systems retain combustion-engine emissions and maintenance requirements. Fuel cells require clean hydrogen and dependable refuelling networks. Recycling and second-life use require traceability and safe state assessment.

Regulatory compliance includes electrical safety, electromagnetic compatibility, crash protection, battery transport, charging standards, hydrogen storage, functional safety, and high-voltage repair qualifications. Employers must provide documented procedures, suitable PPE, training, emergency planning, and controlled access to energized equipment.

Best-Practice Principles

• Match architecture to duty cycle, route, climate, payload, and infrastructure.
• Separate power, energy, efficiency, and emissions measurements.
• Use manufacturer procedures for isolation, measurement, and pack service.
• Treat BMS estimates as model-based values requiring appropriate diagnostic interpretation.
• Control temperature and avoid unnecessary high-SOC or high-temperature storage.
• Evaluate lifecycle impacts using declared boundaries and transparent assumptions.
• Record charging, fault, and thermal data to support maintenance decisions.
• Validate new software or AI tools before using them in safety-critical decisions.

Chapter Summary

Electrified vehicles use different combinations of batteries, electric motors, inverters, combustion engines, and fuel cells. Mild hybrids provide limited electrical assistance; full hybrids combine engine and motor operation; PHEVs add external charging; BEVs rely entirely on stored electrical energy; and FCEVs generate electricity from hydrogen while using a buffer battery.

Power determines acceleration and grade capability, whereas energy determines range. Motor and inverter efficiency vary with operating conditions. Battery packs are assembled from series and parallel cell connections and require BMS supervision for voltage, temperature, SOC, SOH, balancing, contactor operation, and fault protection. AC charging uses an onboard charger, while DC fast charging supplies controlled battery voltage directly through external equipment.

Regenerative braking recovers part of the vehicle’s kinetic energy, but friction braking remains essential. Thermal management controls performance, life, and safety. High-voltage work requires isolation, lockout/tagout, PPE, and verified absence of voltage. Fuel-cell performance depends on stack efficiency and the upstream hydrogen pathway. Lifecycle evaluation must include manufacturing, energy supply, use, maintenance, recycling, and ethical supply-chain issues. Sound engineering decisions integrate technical performance, economics, infrastructure, safety, and environmental evidence.

Key Terms

Battery-electric vehicle (BEV): Vehicle propelled solely by electrical energy stored in a rechargeable battery.

Battery-management system (BMS): Electronic system that monitors and protects a battery and estimates its operating states.

Blended braking: Coordinated use of regenerative and friction braking.

Cell: Basic electrochemical unit that produces voltage and stores energy.

Depth of discharge (DOD): Fraction of a battery’s usable capacity removed during operation.

Fuel-cell electric vehicle (FCEV): Electric vehicle in which a fuel cell generates electricity from hydrogen.

Hybrid electric vehicle (HEV): Vehicle combining an internal-combustion engine with electric propulsion or assistance.

Inverter: Power-electronic converter that changes battery DC into controlled motor AC and reverses the flow during regeneration.

Lithium-ion battery: Rechargeable battery technology using lithium-ion movement between electrodes.

Onboard charger: Vehicle unit that converts AC charging electricity into battery-compatible DC.

Power-split hybrid: Hybrid architecture combining mechanical and electrical energy paths.

Regenerative braking: Recovery of vehicle kinetic energy as electrical energy during deceleration.

State of charge (SOC): Estimated remaining battery charge relative to a defined usable capacity.

State of health (SOH): Measure of battery condition relative to a reference new or specified condition.

Thermal runaway: Self-accelerating battery heating that may lead to venting, fire, or cell propagation.

Traction motor: Electric machine that supplies wheel torque or absorbs energy during regeneration.

Vehicle-to-grid (V2G): Bidirectional exchange of electrical energy between a vehicle and the electricity grid.

High-voltage interlock loop (HVIL): Safety circuit that detects opened connectors, covers, or access points in a high-voltage system.

Review Questions

Short Answer Questions

1. Distinguish electrical power from electrical energy in a vehicle.
2. What are the principal functions of a battery-management system?
3. Why does regenerative braking not recover all of the vehicle’s kinetic energy?
4. Compare AC charging with DC fast charging.
5. State two hazards associated with high-voltage vehicle service.

Long Answer Questions

1. Compare mild hybrid, full hybrid, plug-in hybrid, BEV, and FCEV architectures, including suitable applications and limitations.
2. Explain the construction and operation of a lithium-ion traction battery pack.
3. Describe how an inverter and traction motor provide both propulsion and regenerative braking.
4. Explain the role of thermal management in battery performance, life, and safety.
5. Discuss why lifecycle assessment provides a more complete comparison than tailpipe emissions alone.

Analytical / Application Questions

1. A fleet travels fixed daily routes and returns to one depot each night. Develop a decision framework for choosing between BEVs and PHEVs, identifying the measurements and infrastructure data required.
2. A vehicle shows a large cell-voltage difference during acceleration but normal voltage at rest. Propose a diagnostic investigation and explain possible causes.
3. Evaluate whether an FCEV or BEV is more appropriate for a high-utilization fleet, considering energy supply, refuelling or charging time, efficiency, infrastructure, safety, and lifecycle emissions.

Multiple Choice Questions with Answers

Question 1

Which vehicle architecture can normally propel the vehicle using electricity alone for a meaningful operating period and can also be externally charged?

A. Mild hybrid

B. Plug-in hybrid

C. Conventional diesel vehicle

D. Non-electric fuel-cell-free vehicle

Correct Answer: B. Plug-in hybrid

Question 2

What is the primary function of an inverter in a battery-electric powertrain?

A. Convert battery DC into controlled motor AC

B. Store hydrogen under pressure

C. Dissipate all regenerative energy as heat

D. Reduce tyre rolling resistance

Correct Answer: A. Convert battery DC into controlled motor AC

Question 3

A battery pack has 100 series-connected cells, each with a nominal voltage of 3.7 V. Ignoring losses, what is the nominal pack voltage?

A. 3.7 V

B. 37 V

C. 100 V

D. 370 V

Correct Answer: D. 370 V

Question 4

Which condition commonly causes regenerative braking power to be reduced?

A. Battery already near its maximum permitted SOC

B. Low vehicle mass only

C. Clean windscreen glass

D. High tyre tread depth

Correct Answer: A. Battery already near its maximum permitted SOC

Question 5

In the simplified wheel-power relationship P_w = F_w v, what does F_w represent?

A. Battery capacity

B. Tractive force at the wheels

C. Fuel-cell efficiency

D. Motor angular speed

Correct Answer: B. Tractive force at the wheels

Question 6

What is the purpose of passive cell balancing?

A. Increase hydrogen pressure

B. Dissipate charge from cells with higher voltage

C. Convert AC directly into wheel torque

D. Replace the vehicle’s friction brakes

Correct Answer: B. Dissipate charge from cells with higher voltage

Question 7

Which action is essential before touching exposed high-voltage conductors?

A. Assume the vehicle is safe because it is switched off

B. Verify absence of voltage using an approved procedure

C. Disconnect only the 12 V battery and begin work

D. Increase the accelerator command

Correct Answer: B. Verify absence of voltage using an approved procedure

Question 8

What is the main electrochemical product at the exhaust of a hydrogen proton-exchange-membrane fuel cell under normal operation?

A. Water

B. Petrol

C. Sulfur dioxide

D. Lead oxide

Correct Answer: A. Water

Question 9

If a traction system delivers 20 kW to the wheels at an overall battery-to-wheel efficiency of 0.80, approximately what battery power is required?

A. 4 kW

B. 16 kW

C. 20 kW

D. 25 kW

Correct Answer: D. 25 kW

Question 10

Why can a lifecycle comparison favour a BEV despite higher manufacturing emissions?

A. BEVs always require no electricity

B. Their use-phase emissions and energy consumption may be lower over the vehicle lifetime

C. Battery manufacture produces no emissions

D. Lifecycle analysis excludes electricity production

Correct Answer: B. Their use-phase emissions and energy consumption may be lower over the vehicle lifetime