EV-14 — Thermal Management

ASSUMPTION — This lesson covers the thermal architecture at the system level. Deep technical content on battery thermal management is in BMS Academy → BMS-12.

1. Why Thermal Management?

The battery, motor, and inverter produce heat while working. The battery must stay within a temperature range: too cold lowers performance/charging, too hot raises accelerated-aging risk.

2. Cooling Methods

• Liquid cooling — the most common, via a coolant loop.
• Air cooling — simple but less effective.
• Refrigerant cooling — strong cooling via a chiller.

3. Chiller, Heat Pump, and PTC

• Chiller — cools the coolant using the refrigerant loop.
• Heat pump — reverses the refrigerant loop to heat the cabin (high COP).
• PTC heater — resistive heating; simple but less efficient.

FACT — A heat pump can move more heat than the electricity it consumes (COP > 1), but its efficiency drops in very cold conditions.

4. Behavior in Cold and Hot Weather

• Cold — power/charging limits drop until the battery warms (thermal derating).
• Hot — power may be limited to protect the battery/motor.

5. Preconditioning

FACT — Bringing the battery to its ideal temperature before fast charging (preconditioning) improves the charging curve and shortens the session.

6. FAQ

Why is the battery cooled?

FACT — Temperature is kept in a band for both performance and life; overheating accelerates aging, and cold reduces power.

What does the chiller do?

FACT — It cools the battery/motor coolant via the refrigerant circuit, removing heat.

7. Summary

• Thermal management keeps the battery in a safe temperature range.
• There are liquid/air/refrigerant cooling methods.
• The chiller cools; the heat pump/PTC heat.
• Preconditioning improves fast charging.

8. Sources and Verification Note

Concepts are established textbook-level knowledge.

• DOE AFDC, SAE J1715.

Next Lesson

• EV-15 — Vehicle Control Architecture: VCU, BMS, inverter, and ECU communication.