I have that system. The Blue Mountain EFIS is powered by a small 12V auxiliary battery, that is fed by a Shottky diode from the main bus. When starting to fly, I turn on the EFIS switch, and only the BM unit comes up, after it has booted, I can observe engine gauges, program the GPS portion, etc.  Then I turn on main buss and start the engine. The aux battery on the BM unit is isolated from the main bus by the diode, therefore does not sag in voltage with the starter.

This also lets me shut off the BM unit last, after engine shutdown and main power off.
Bill Schertz
KIS Cruiser #4045
N343BS
Phase I testing
----- Original Message ----- From: "Greg Ward" <gregw@onestopdesign.biz>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Saturday, June 06, 2009 9:37 PM
Subject: [FlyRotary] Re: Battery Isolation diodes

Hey John;
Agree with you on the CB's, but it sounds like a pain in the a... to have to do that every time you are sitting on the ground programming a GPS.  I think they were talking more of a separate switch, from the battery, that you could hit, and power the GPS/EFIS only, and then when that was done, going onto engine start.  I am no electrical genius, which is why I was asking if a switch over like this is possible.  In other words, hit a switch, program, and then go to engine start without losing power to the GPS/EFIS, forcing a reboot.
Greg

----- Original Message ----- From: "John" <downing.j@sbcglobal.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Saturday, June 06, 2009 6:10 PM
Subject: [FlyRotary] Re: Battery Isolation diodes

Greg, I have fuses going to the EC-2 and the coils, if I had CB's I could switch off the CB's, now I need to pull the fuses, another good reason to use CB's.  JohnD
----- Original Message ----- From: "Greg Ward" <gregw@onestopdesign.biz>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Saturday, June 06, 2009 8:32 PM
Subject: [FlyRotary] Re: Battery Isolation diodes

Got them Ed, and thanks.  One quick question.  I went to an AOPA safety seminar, and they recommended a separate ground switch for the GPS, and related equipment, so that they could be programmed without the engine running, as that has been known to take some time, and your head is down with a prop running.  Has anybody done this?  Any diagrams?
Greg Ward

eanderson@carolina.rr.com

http://www.andersonee.com

http://www.dmack.net/mazda/index.html

http://www.flyrotary.com/

http://members.cox.net/rogersda/rotary/configs.htm#N494BW

http://www.rotaryaviation.com/Rotorhead%20Truth.htm


-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On
Behalf Of Ernest Christley
Sent: Saturday, June 06, 2009 4:23 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Battery Isolation diodes

Ed Anderson wrote:

Thanks, Tracy

I was unaware (never thought about it) of the association - perhaps
not having an isolation diode is one reason I never had any "Noise
Problem" with the EC2 {:>)

Thanks for the information

Ed

When wiring up the diode, it should be fairly simple to drop in a large
value mylar capacitor to conduct the noise. My experience with
electrolytics is that they can be poorly made and leak. The mylars would
be more robust in the environmental extremes of an airplane.

In any case, I thought the diode was just for a backup. The switch would
stay in the same position it has always occupied, so noise would be
absorbed by the battery as it always has. The EC2 would have to be on
the battery side of the switch, which would make it even more noise
isolated when hidden behind the diode.

-- http://www.ernest.isa-geek.org



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