GAD27 +/or VPX +/or Bus Manager

[ERushing]

For those adopters of EFII's complete system (fuel injection & ignition), has anyone proceeded without the Bus Manager?

I've begun work on my electrical architecture and have run into a head scratcher. I like aspects of all three boxes - GAD27, VPX-Pro and EFII's Bus Manager. But using all three seems like extreme overkill and there's some crossover.

My Mission: RV10 Cross Country Machine w/ Full IFR
My Panel: Garmin G3X w/ GTN650 in Aerosport 310 panel. - Set up for 2 pilot IFR.
- Autopilot controller on panel
- Remote Audio Panel
- Remote transponder
- Remote second Comm
- Archer wingtip Nav Antenna, possibly two.
My Engine: IO-540 with full EFII injection & ignition
My general Electrical Architecture: Dual battery, Dual alternator.
- Still struggling with the specific implementation on this one... I'd like one battery for engine starting and main bus and one battery for critical avionics, likely joined by a Schottky Main to Essential.

Don't get me wrong, the Bus Manager is a fine product but I'm considering going without it because it seems an awful lot to pay for auto-pump-switchover. I don't want the dual-battery management aspect of it. If I can't start on one battery, I'm not going anywhere.. I'm not crazy about the diodes feeding the essential bus. I'm not crazy about a single relay controlling both pumps.

I'd really like to proceed with the VPX because I don't have panel space for breakers. My primary concern is that it doesn't elegantly handle a dual-battery architecture.

I like the GAD27 for the trim mixing, integration with G3X and voltage stabilization.

Anyone done EFII without the Bus Manager? I'm pretty early into my electrical architecture planning so input is appreciated!.
Thanks!

[Bill.Peyton]

Hi Eric,
Your plan for a dual bus is indeed a good one considering the dependency on the electrical system to keep you in the air. I might suggest you take a look at the Blue Seas charge relay products. I am using a model 7610 to automatically cross connect my two batteries/buses. I also have the VP system to manage my primary power bus. For the secondary bus I used a fuse block and fuses with series schotkey diodes to force the voltage on the secondary LRU power inputs to be slightly lower than the primary thus forcing the LRU to operate off the primary bus for normal operations. For the LRUs that did not have dual power pins I used relays to auto switch in case of a main bus power failure. My system is 100% redundant, with two alternators and two batteries. The only issue that arises by using the VP, in terms of single point failure, are the flaps and the trim system. I recently implemented an emergency trim switch which bypasses the VP and is driven by the secondary bus. I have not backed up he flaps since, as long as they are not engaged, you can fly without them.
I have almost 600 hours on the system and it has performed flawlessly,although I have never had a failure of the primary bus, it's comforting to know if I do I have multiple options.