EVITP EV Technology Fundamentals 3 — Questions and Answers
Question 1: What is the maximum continuous current permitted for AC Level 2 charging under SAE J1772?
- 32 A
- 48 A
- 80 A (Correct answer)
- 100 A
Correct answer: 80 A
SAE J1772 allows AC Level 2 charging up to 80 A.
Question 2: Which component monitors individual cell voltages, temperatures, and state of charge in an EV traction battery?
- Onboard charger
- Battery management system (BMS) (Correct answer)
- DC-DC converter
- Traction inverter
Correct answer: Battery management system (BMS)
The BMS tracks cell conditions and protects the pack from overcharge, overdischarge, and overheating.
Question 3: During regenerative braking, what happens to the vehicle's kinetic energy?
- It is dissipated as heat in the brake rotors
- It is converted to electrical energy and stored in the battery (Correct answer)
- It is sent back to the EVSE through the connector
- It is used only to charge the 12 V accessory battery
Correct answer: It is converted to electrical energy and stored in the battery
The traction motor acts as a generator, converting kinetic energy into electricity that recharges the battery.
Question 4: An EV battery is rated at 75 kWh. What does this figure describe?
- Maximum charging power
- Peak motor output
- Energy storage capacity (Correct answer)
- Maximum discharge current
Correct answer: Energy storage capacity
Kilowatt-hours measure energy, so 75 kWh is the battery's storage capacity.
Question 5: During a DC fast-charging session, where does the AC-to-DC conversion take place?
- In the vehicle's onboard charger
- In the vehicle's traction inverter
- Inside the off-board DC charging equipment (Correct answer)
- In the vehicle's DC-DC converter
Correct answer: Inside the off-board DC charging equipment
DC fast chargers contain their own rectifiers and deliver DC directly to the battery, bypassing the onboard charger.
Question 6: What is thermal runaway in a lithium-ion battery?
- A slow loss of capacity over years of cycling
- A self-sustaining reaction where rising temperature releases more heat (Correct answer)
- Temporary range loss in cold weather
- A software fault that limits charging speed
Correct answer: A self-sustaining reaction where rising temperature releases more heat
Thermal runaway is a chain reaction in which heat triggers reactions that produce more heat, which can lead to fire.
Question 7: Which vehicle type has both an internal combustion engine and a battery that can be recharged from an external outlet?
- Battery electric vehicle (BEV)
- Plug-in hybrid electric vehicle (PHEV) (Correct answer)
- Conventional hybrid electric vehicle (HEV)
- Fuel cell electric vehicle (FCEV)
Correct answer: Plug-in hybrid electric vehicle (PHEV)
A PHEV combines a gasoline engine with a battery charged by plugging into EVSE.