Hi all:
I am installing a 4500EF and 3500EM in my RV-7 project. The airplane has a standby battery for the dual electronic ignition system (that is the only use for this battery). We have figured out a way to isolate the aux battery voltage for display "somewhere". Is there any way to display this voltage on the AFS 4500/3500??
Thanks!!
Doug Weiler
You can display a "backup voltage" on one or both of your EFIS screens. However, it will run on that backup battery if you loose your main battery.
Trevor: Is that true even if you have the internal backup battery in the 4500 and 3500?Originally Posted by Trevor Conroy
Doug
Yes, it will run off of main power, then backup power, then internal battery. So if you didn't want it to use your backup battery, you'd want to install a switch (or just pull the C/B's on your Essential buss)
Doug,
While my situation will not work completely for you, it might help others here.
I have 2 battery systems. The Main and the Essential batteries and their busses. I warm up my avionics through the essential bus. When I am ready to start, only the fuel pump and starter are connected to the main bus.
After starting, the 2 busses are connected via a switch and a diode to charge the essential battery.
I currently have two 3500’s and as the wiring diagrams say, I have both connected via pin 1 to the main battery. Pin 15 is connected to the essential battery. Through setup on the 3500’s, the left one has the battery voltage display the Main and the right display the backup (pin 15) voltage. Problem is, IT DOESN’T WORK. Tech looked into it and I have been told that they can’t correct it. The left reads the main bus voltage and the right reads a couple tenths of a volt (diode back voltage).
Here is the work around that was given to me. On the Left, connect pin 1 to the Main battery, pin 15 to the Essential battery and configure it to read the Main. On the Right, connect pin 1 to the Essential battery, pin 15 to the Main battery and configure it to read the Main.
Doing this, the left 3500 will display the main voltage and the right 3500 will display the essential bus voltage. It has been to hot here for me to climb under the console just to make the wiring change so for right now I can not confirm that this works. But it should.
Gary Blankenbiller
RV-10 N2GB
Thanks... we also thought about wiring in a small "momentary-on" pushbutton and wire such that when it is pushed, it would feed the aux battery power to the 3500EM and thus momentarily read the aux battery voltage. I think that is doable. Does that sounds logical?
You could do that. It would accomplish the task you are after.
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