APU 757 issue

OK so. Why do i need to turn on the battery to activate the AUXILLARY power unit??? Surely when you acti vate the APU, its to reduce the load on the battery. It defeats the purpose. On the airbus i fly, we do APU on, and leave battery off. Like bruh


You need the battery to start the APU because the APU is an engine itself. The battery provides power to an electric igniter/motor that starts the APU. We don’t have ground power units in IF yet to supply power to the APU, so the battery is needed. Once the APU starts generating power on its own, it can use power to start the engines. The aircraft battery will then be recharged by the engine running.


Exactly what boat said,

In an IRL start-up of any aircraft, the batteries are always turned on, then the ground power (if any), and APU. APU usually takes roughly 50-70 seconds to start-up, in Infinite Flight, I believe it’s only 15.


@ItsBlitz Don’t you need to keep the battery on for the instrument displays? Or have I been doing that wrong for over a year 😂

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One the battery is on, you only get the lights and the battery power for the engines,

After the APU is turned on, it powers majority of the aircraft until the main engines are on. So then the displays will turn on

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So you don’t really need the battery on after full APU powerup?

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No, you had it correct the first time.

Main batts are used throughout the entire flight, APU is shut off after engine start and turned back on after landing :)

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To make is simpler, APU supplies the aircraft with power when the engines are not turned on.

Oh ok good. I was a little confused at first but we’re all on the same page now!

Please see the explanation by @Yacht. That is correct. Same holds true for the other aircraft that have an APU in the fleet. 🙂

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Right. I must be going crazy. Thx

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