What is the minimum battery temperature required to start the auxiliary power unit?

What is the minimum battery temperature required to start the auxiliary power unit?

• A. -40 degrees Celsius
• B. -20 degrees Celsius
• C. 0 degrees Celsius
• D. -10 degrees Celsius

Answer: (B)

Cold-temperature battery performance matters for starting the APU. When the battery is very cold, its ability to deliver high cranking current and maintain voltage under load drops. The APU start requires a short, high-current surge, so the battery must be above a certain temperature to supply enough current reliably. The minimum temperature set for starting the APU is -20 degrees Celsius, ensuring the battery chemistry can still produce the necessary current. If the battery is colder than that, starting can fail due to insufficient current. Warmer conditions (0 C or -10 C) are above the threshold and generally allow a start.

Cold-temperature battery performance matters for starting the APU. When the battery is very cold, its ability to deliver high cranking current and maintain voltage under load drops. The APU start requires a short, high-current surge, so the battery must be above a certain temperature to supply enough current reliably. The minimum temperature set for starting the APU is -20 degrees Celsius, ensuring the battery chemistry can still produce the necessary current. If the battery is colder than that, starting can fail due to insufficient current. Warmer conditions (0 C or -10 C) are above the threshold and generally allow a start.