Chapter 9

Question 1

1. Which of the following accurately describes a buck converter?
   A. Step-up transformer
   B. Step-down transformer
   C. Inverter module
   D. Rectifier module

Answer 1

B. Step down transformer

Question 2

2. What is the function of a typical battery disconnect unit (BDU)?
   A. Power distribution
   B. Communications with chassis data bus
   C. Current sensing
   D. All are correct.

Answer 2

D. All of the above

Question 3

3. Technician A says that during a discharge cycle, a battery generates heat. Technician B says that the faster a battery is discharged, the more heat is generated. Who is correct?
   A. Technician A only
   B. Technician B only
   C. Both A and B
   D. Neither A nor B

Answer 3

C. Both a and b

Question 4

4. What type of EESS cooling system is used in most current EV EESS?
   A. Direct liquid cooling
   B. Indirect liquid cooling
   C. Air-cooling
   D. Phase transition cooling

Answer 4

B. Indirect liquid cooling

Question 5

5. What is the temperature range within which most current li-ion batteries function at optimum efficiency?
   A. 50°F–131°F (10°C–55°C)
   B. 41°F–68°F (5°C–20°C)
   C. 32°F–59°F (0°C–15°C)
   D. 140°F–185°F (60°C–85°C)

Answer 5

A. 50°F–131°F (10°C–55°C)

Question 6

6. Technician A says that EESS li-ion cells in a battery pack are arranged in parallel. Technician B says that in an EESS, multiple battery packs are arranged in series to form an EESS string. Who is correct?
   A. Technician A only
   B. Technician B only
   C. Both A and B
   D. Neither A nor B

Question 7

7. When a regenerative braking cycle is engaged in a current vehicle with an electric powertrain, which of the following is true?
   A. The driveshaft turns in reverse.
   B. The ICE compression retarder is actuated.
   C. The traction motor generates ac.
   D. The traction motor generates dc.

Answer 7

C. The traction motor generates ac

Question 8

8. Technician A says that PME modules are used to rectify ac to dc. Technician B says that PME modules are used to invert dc to ac. Who is correct?
   A. Technician A only
   B. Technician B only
   C. Both A and B
   D. Neither A nor B

Answer 8

B. Tech b only

Question 9

9. What solid-state device performs the high-speed switching required in current EV drive train PME modules?
   A. IGBT
   B. FET
   C. Diode
   D. Electromechanical rotary wheel

Answer 9

A. IGBT

Question 10

10. When a string control unit (SCU) is used in an EV powertrain, where is it usually located?
    A. Engine ECM
    B. Battery disconnect unit (BDU)
    C. Inverter module
    D. Chassis management module

Answer 10

B. Battery disconnect unit

Question 11

11. Which type of the following EESS cooling systems is said to have the highest efficiency?
    A. Phase transition
    B. Forced air
    C. Direct liquid cooling
    D. Indirect liquid cooling

Answer 11

C. Direct liquid cooling

Question 12

12. Technician A says to ensure that a battery pack is safe to handle without high-voltage PPE, the EV electrical isolation switch(es) must be opened. Technician B says that when a battery pack is disconnected from the EESS bank, it can be regarded as being in an electrically neutral state. Who is correct?
    A. Technician A only
    B. Technician B only
    C. Both A and B
    D. Neither A nor B

Answer 12

D. Neither a nor b