re: the 350 diagram, they did some interesting things.
I wonder if you have more information about:
- what is in the "junction boxes"
- how they wired the contactors
Here's a question: where should you source the power for
your xfeed contactor coil, left batt coil, right batt coil?
e.g. if you source the right batt coil from the right batt
itself, you can't charge that battery unless it's already in pretty good shape.
My conclusion was as follows:
- xfeed fed from essential bus. It will be up if one
of the two batt busses is up.
- right batt from right batt (directly) and left batt bus
- left batt from left batt (directly) and right batt bus
As for your question, I have a clear and
definitive answer: I don’t know. Except I think (working from
memory of the figure) the relays are powered from the essential bus. Have
a close look.
As for your conclusions, I entirely agree.
I first noted some years ago when doing the preliminary design that the
AeroElectric Connection layout for dual alternator dual bus has an interesting
deficiency. If you flatten both batteries, the power from the ground
power supply can only turn its respective buss, and not the other. I put
in a switch and current limiting resistor that allows the B buss on my plane,
the one getting ground power, to feed power to the A buss relay to bring the A
battery on line. Powering the relays off the essential buss achieves the
result automatically. I wish I had seen the Columbia schematic
much earlier.
Fred