Master switches query

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EmileB
Airman Basic
Posts: 7
Joined: 05 Jan 2021, 22:50

Master switches query

Post by EmileB »

I'm new to the A2A C172 (though a simmer for 30 years) and discovering things as I go, running P3DV4.5 HF3. My question concerns the following observation :
When both alternator and battery master switches are OFF, switching the battery ON first will only switch on the battery and the alternator can be switched on independently. But when the alternator is switched ON first, it also switches on the battery.
Switching the masters OFF does the opposite :
When both alternator and battery master switches are ON, switching the alternator OFF first will only switch off the alternator and the battery can be switched off independently. But when the battery is switched OFF first, it also switches off the alternator.
Is this how it is supposed to work in the real aircraft ? I'm just curious !

Thanks,
Emile.
Cheers,
Emile.

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Nick - A2A
A2A Captain
Posts: 13734
Joined: 06 Jun 2014, 13:06
Location: UK

Re: Master switches query

Post by Nick - A2A »

Hi Emile and welcome.

Yes, the behaviour of the battery/alternator switch you describe is common to quite a few small GA types I believe. The interlocking split rocker switch is designed so that you can switch the battery on without having the alternator on. However, it prevents you from leaving the alternator on when the battery is off, which I think may be to prevent voltage spiking from damaging the alternator.

Thanks,
Nick
A2A Simulations Inc.

EmileB
Airman Basic
Posts: 7
Joined: 05 Jan 2021, 22:50

Re: Master switches query

Post by EmileB »

Hi Nick,

Thanks very much for your explanation - that makes a lot of sense. I now wish, though, that I had posted my question BEFORE spending almost an entire afternoon trying every trick in the book to get the switches to operate independently :oops:
Cheers,
Emile.

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Nick - A2A
A2A Captain
Posts: 13734
Joined: 06 Jun 2014, 13:06
Location: UK

Re: Master switches query

Post by Nick - A2A »

Haha - you're welcome Emile. If you have any further questions, you know where we are. :)

Thanks,
Nick
A2A Simulations Inc.

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