AARC EV & Hybrid Vehicle Processing 4 — Questions and Answers
Question 1: Which type of fire suppression system is recommended by NFPA 855 for indoor EV battery storage areas?
- Dry chemical powder suppression
- Halon 1301 total flooding
- Extended application sprinkler systems with adequate water supply (Correct answer)
- CO2 total flooding
Correct answer: Extended application sprinkler systems with adequate water supply
NFPA 855 recommends water-based extended application sprinklers because cooling is the only effective method to suppress lithium battery thermal runaway.
Question 2: A plug-in hybrid electric vehicle (PHEV) arrives at the recycling yard still plugged into a Level 2 EVSE charge cord. What is the first action?
- Cut the charge cord immediately
- Unplug the EVSE from the wall outlet before touching the vehicle (Correct answer)
- Unplug the cord from the vehicle inlet first
- Drive the vehicle to discharge the battery
Correct answer: Unplug the EVSE from the wall outlet before touching the vehicle
Disconnecting the EVSE from the power source first de-energizes the cord and eliminates shock hazard before handling the vehicle inlet.
Question 3: What information must appear on the label of a used EV battery pack shipped as universal waste?
- 'Universal Waste — Battery' and the accumulation start date (Correct answer)
- Only the recycler's name and address
- The original vehicle VIN and battery serial number
- The state of health percentage
Correct answer: 'Universal Waste — Battery' and the accumulation start date
EPA universal waste rules require the label 'Universal Waste — Battery' and the date accumulation began to track the 1-year storage limit.
Question 4: Why should an EV or hybrid battery pack never be stored in a fully discharged (0% SOC) state for extended periods?
- It voids the R2 certification
- Deep discharge causes lithium plating and irreversible capacity loss (Correct answer)
- It triggers automatic BMS cooling fans continuously
- Insurance policies prohibit it
Correct answer: Deep discharge causes lithium plating and irreversible capacity loss
Extended storage at near-zero SOC causes lithium plating on anodes and electrolyte degradation, permanently reducing battery capacity.
Question 5: Which component of a hybrid vehicle's regenerative braking system is most likely to retain lethal voltage after the ignition is off?
- The DC-DC converter output capacitors (Correct answer)
- The hydraulic brake booster
- The wheel speed sensors
- The ABS modulator valve
Correct answer: The DC-DC converter output capacitors
DC-DC converter capacitors can hold hundreds of volts for several minutes after shutdown, presenting a lethal shock hazard.
Question 6: An AARC recycler purchases a fleet of retired electric delivery vans. Before auction or dismantling, what document should be requested from the fleet operator?
- Original window sticker (Monroney label)
- Battery history report including charge cycles and thermal events (Correct answer)
- EPA emissions certificate
- CARB zero-emission vehicle credit transfer form
Correct answer: Battery history report including charge cycles and thermal events
Battery history data reveals thermal events, deep discharges, and total cycle count, which are critical for assessing resale value and safety risk.
Question 7: What does 'state of charge' (SOC) refer to in an EV battery context?
- The number of charge-discharge cycles completed
- The current available energy as a percentage of total capacity (Correct answer)
- The voltage across the HV bus bars
- The internal resistance of the cells
Correct answer: The current available energy as a percentage of total capacity
SOC is analogous to a fuel gauge — it represents remaining energy as a percentage of the battery's full rated capacity.
AARC EV & Hybrid Vehicle Processing 4
Which type of fire suppression system is recommended by NFPA 855 for indoor EV battery storage areas?