Electrical System Planning - Input requested

[akarmy]

Like I really needed to ask. I'm sure I'll get a full dose of the input I desire.

The basics first. I'm building a very simple VFR only RV-8. Single Dynon Skyview 10" with a GTR200 radio / intercom. LED lights, dual P-MAGS, manual trims. No autopilot initially, but wired for the servos with brackets installed. PC680 on the firewall, B&C starter, Plane power alternator "with OV"...

My last plane had a basic Aeroelectric Z-11 primary / ebus. I'm looking to go even simpler with this one. Don't think I really need the endurance bus concept as the Dynon has a backup battery so what else is really needed to continue going or to land? Lastly, I'm leaning towards the dreaded avionics switch as I have a few devices that don't have a power switch and while they can be on during start, I would rather be able to cut them off if needed.

Here's what I have thus far. What am I missing?

[n82rb]

What you have drawn is almost identical to my rv-4 system. All I would add is put in a couple of extra breaker/fuses on the main bus just in case. I would also upsize the wiring and breaker to the avionics buss I think 10 amps is a little low. Look at the worst case the auto pilot starts trimming just as you key the mike and start transmitting an the transponder responds all at the same time. You don't want to loose the avionics buss right then. Just size the breaker/fuse,wire, and buss bar for 15 amps or so and you will be just fine.

Bob burns
Rv-4
n82RB

[zav6a]

Starter contractor and a solenoid? Am I missing the stater switch?

[alpinelakespilot2000]

Hi Andy-

If you use a Plane Power alternator with built in OV you can ditch the external OV protection.

Otherwise your plan is very simple and very similar to mine. Like you I went ahead and used a avionics bus. In particular, I used it so that I could put my Dynon on it and start up with the av buss off and the Dynon running on its internal battery. Though I know it's not necessary per Dynon, it does isolate it from start-up spikes and also provides confirmation that the internal back up battery is working.

Also, like you, I think the e-bus is entirely unnecessary for most of the aircraft we build, especially VFR a/c. If I lose electrical power it's easy enough just to flip a few switches for anything not immediately needed.

Ditto the above post regarding upsizing av bus breaker a bit.

Sounds like you are making progress!

[MCA]

Any reason you need those items on the battery bus? You could eliminate the batt bus altogether and put those on the main bus. Also, why are there switches on those two items?

P-Mags should have a switch so you can test the on-board generator.

As mentioned, starter switch and upsize the avionics master circuit.

Do you want switches on the exterior lights?

Electric trim? What type of flap control?

The Plane Power alternator has OV built in - you don't need a separate module as indicated.

Why do you have a fusible link for the alt field? Why not a 5A breaker? Also, you have both 18 & 20 AWG wire for the field. Recommend 18 for all.

[Noah]

Having the alternator B-lead attach to the main contactor rather than the starter contactor eliminates a failure point (the starter terminal). Also the avionics bus switch is a single point failure. If you have internal batts on your critical avionics this is less of an issue. Some people install two avionics bus switches in parallel, one to each end of the bus bar. But these are minor points, really.

[krw5927]

Have you already installed the Advanced AOA? If so, then disregard. If not, a perfectly fine AOA indication can be had on Skyview, either using the Dynon pitot or making your own.

[N941WR]

I don't see fuses for your landing, taxi, and position lights. Since your -8 will be a trail dragger, you want to switch your landing and taxi lights independently. That is because your landing light will be aimed parallel to your wings and the taxi light will be aimed down.

I don't see a fuse for your Dynon's engine module, which should be on the main buss.

Regarding your P-mags, you can always use pullable breakers, which will allow you to drop power to them, for your pre-flight. (That or look at how I wired mine.)

Placing the wire size on your schematic for each circuit would be helpful.

[akarmy]

Originally Posted by n82rb

All I would add is put in a couple of extra breaker/fuses on the main bus just in case. I would also upsize the wiring and breaker to the avionics buss I think 10 amps is a little low.

Sounds good on both fronts. I'll add those in. Thanks!

[akarmy]

Originally Posted by alpinelakespilot2000

If you use a Plane Power alternator with built in OV you can ditch the external OV protection.

This is one thing I have not seen any drawings of? How the Plane Power OV system works? anyone know a source for a picture?