I am currently building small airplane with rotax 912Is and I want to ask if I can use battery relay together with master switch? 

I drew some wiring diagram and I am wondering if it is correct to put backup battery switch in front of battery relay.

Thx in advance for some advice



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  • Re: Battery relay for 912iS

    by » 2 years ago

    Yes, you want the Backup Power Switch to bypass the Battery Relay.
    You also want the Starter Relay connected directly to the Battery.

    Depending on the geometery of the wiring, A Master Switch carryng the full load without a Battery Relay is possible.
    This isn't an Airliner, the loads are light and the generator is limited to 30 amps.
    A heavy duty DPDT Master switch powering a split bus can eliminate the complexities of a Master Relay.
    Put the Avionics on one side and the Lighting circuits on the other.
    Todays Panels do not use anywhere near the current that they did 30 years ago.

    Bill Hertzel
    Rotax 912is
    North Ridgeville, OH, USA
    Clicking the "Thank You" is Always Appreciated.

    Thank you said by: Tomas Vecera

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