EVT EVT Thermal Management & Cooling Systems

Question 1

What is the primary purpose of the Battery Thermal Management System (BTMS) in an electric vehicle?

Accepted Answer

Maintain battery pack temperature within an optimal operating range to maximize life and performance

Answer

Increase battery charging speed by reducing resistance

Answer

Cool the electric motor windings during regenerative braking

Answer

Pre-heat cabin air using waste heat from the battery

Question 2

A liquid-cooled battery pack uses ethylene glycol–water (EGW) coolant. What is the MAIN advantage of liquid cooling over air cooling for high-capacity packs?

Accepted Answer

Higher heat transfer coefficient enabling tighter temperature uniformity across cells

Answer

Lower system weight

Answer

Simpler maintenance with no pump required

Answer

Lower manufacturing cost

Question 3

Which component in an EV thermal system transfers heat between the refrigerant circuit and the battery coolant loop without mixing the fluids?

Accepted Answer

Chiller (refrigerant-to-coolant heat exchanger)

Answer

Expansion valve

Answer

Condenser

Answer

Accumulator

Question 4

During a hot summer day, a technician notes the EV's available charge rate drops significantly. What is the most likely cause?

Accepted Answer

Battery thermal management system limiting charge rate to prevent overheating

Answer

Low 12V auxiliary battery voltage

Answer

Software update pending restart

Answer

Worn motor brushes increasing resistance

Question 5

What does a negative temperature coefficient (NTC) thermistor do as its temperature increases?

Accepted Answer

Its resistance decreases

Answer

Its resistance increases proportionally

Answer

Its voltage output increases linearly

Answer

Its capacitance increases

Question 6

A technician replaces coolant in a liquid-cooled battery pack. What is a critical step BEFORE refilling?

Accepted Answer

Flush the system with distilled water and verify no contamination or air pockets remain

Answer

Discharge battery to 0%

Answer

Pressurize the pack to 30 PSI to check for leaks

Answer

Remove all 12V fuses