RV-10 Electrical System

[Carl Froehlich]

Originally Posted by AviatorJ

Was hoping the the largest 6ah version it would be closer to 1 hour.

This is example of adding backup batteries as the the risk mitigation tool for single component failure scenarios. The alternative is to create flexibility such that the batteries have a primary and secondary function (e.g. both batteries on line for engine start and normal operations, split when needed to bypass around a fault).

I also was surprised on this 6ah backup battery's very high price tag.

Carl

[AviatorJ]

Mike can't answer your question on how the lines don't get overheated in the engine compartment.

Carl- for me it came down to what I was trying to accomplish. I put a very low risk and impact of losing electrical or attitude indication in VFR and as I always say if I have an issue in IMC my #1 priority is to get out of IMC. So if I can have enough situational awareness to get myself out of the clouds then I'm not particularly worried about getting down safely.

Not being overconfident or passive but I've had an alternator go out, a vacuum pump go out while in IMC and have had to land without landing lights at night... it's not particularly fun to deal with these things but I didn't consider any of those an emergency.

The way I view my setup and in particular the IBBS is that it's the second to the last of 'if all else fails' list. The last on the list is the G5 which has it's own self contained battery. To get to that point I would of had to lose both ADAHRS, both Panels, both Alternators, the VPX, the contactor or the battery itself... Murphy's law says that may happen in that case I'm banking on the G5 to get me to safety... if the G5 goes out then lets hope I can feel the climb or descent enough to get out of the clouds without spinning!

I actually view this set up more as a Dual Alternator, Dual Battery setup. Maybe not with the all the redundancy of the design you sent me but enough to get me safely out without the weight hit.... already getting that with the AC.

[majuro15]

Thanks for the file Justin.

FYI, Flightline has an electric version but most folks are going with an engine driven compressor, just light Air Flow. The only difference is lack of scoop. Both are good systems with folks happy with finished installs.

[ppilotmike]

Originally Posted by majuro15

Thanks for the file Justin.

FYI, Flightline has an electric version but most folks are going with an engine driven compressor, just light Air Flow. The only difference is lack of scoop. Both are good systems with folks happy with finished installs.

Any idea why most prefer the engine-driven compressor? I would think the electric would provide more flexibility for location of components.

[woxofswa]

When I was shopping for an A/C system about 7 years ago, I passed on the electric system because it required a 24v system and a very expensive alternator and battery setup. I also felt like the old school automotive type system would be easier to resource and maintain.

I went with Airflow and the scoop because:

1: I didn't like the idea of sucking up exhaust laden air into the fuselage.

2: I actually like the looks of the scoop.

3: Bill returned my phone call first and I liked his pro-support attitude. He's been great to work with.

I know guys with Flightline who are quite happy with their system.

No A/C system is plug and play. It adds a lot more time to the build than initially appears, and requires initial tweaking and maintenance. However, after 300 hours I am very glad I did it. It isn't just hot (Arizona) weather where it is nice, the RV10 cabin is a greenhouse even in coolish weather and getting the humidity out also makes a much more pleasant flight and must be beneficial to the avionics and cabin materials. I recently returned from a trip to Baja and the amount of water pouring out of the vent on shutdown was amazing even though the OAT wasn't that hot at all.
I would guess that our compressor has run at least a third of our flighttime.

[DanH]

Originally Posted by AviatorJ

Should add three ANR's (or fusible links, or some other high reliability, high capacity circuit interruption device) to the alternator B leads and VPX feed, near the battery master.

[AviatorJ]

Originally Posted by DanH

Should add three ANR's (or fusible links, or some other high reliability, high capacity circuit interruption device) to the alternator B leads and VPX feed, near the battery master.

To break the power connection without having to disconnect the battery?

I'm working through some other things right now, like going with illuminated rockers or toggles with a glare shield dimmable light. What to use on the AC power switch (relay or whatever) so I don't have to run 20 amps of power to the panel for the switch and then back to the tail.

I also received Marc's book in the mail yesterday so will be reading through that.

[DanH]

Originally Posted by AviatorJ

To break the power connection without having to disconnect the battery?

Short any of them, and things get hot real quick. Although a well-trained pilot may eventually open the master contactor and disconnect the battery, there will be a time interval between the short and the switch movement. The process requires detection, realization, decision, and action. In the meantime, nothing good is happening. Think sparks and burning insulation, while your wife screams.

Ok, let's assume our superior pilot disconnects the battery with lightning speed...no indecision, no delay. Does it stop the sparks? Not necessarily. The alternator doesn't drop off line because the battery master was opened. Shutting down the alternator field supply will require another switch selection.

Short any of them with an ANL near the master, and the ANL melts immediately. End of problem; the short path is isolated from the rest of the system. If it was the live alternator B-lead, the VPX will alert a voltage drop, and the pilot brings the other alternator online. If it was the standby B-lead, its ANL pops and nothing else happens. If it was the VPX power feed, the panel goes dark. The pilot switches to the IBBS for power and pushes "Nearest" on the GPS.

http://www.bandc.aero/anlcurrentlimi...rough130a.aspx

[rockbottom]

Justin,
I noticed you're utilizing the IBBS backup battery for the GTN, GDU, GSU 25, and the GEA 24, but no similar/equivalent backup for the GAD 29. As I'm building an -8 with similar components and architecture and haven't flown behind a GTN yet, I'm curious as to how much functionality would be lost between the GTN and the GDU in the event of a main bus failure. Would it be significant if in IMC conditions? I intend to post the same question to the G3X experts at Garmin and maybe others here who have experience with the GTN and G3X will chime in, but wanted to know if not having a backup power source for the GAD 29 was a consideration.
Thanks for posting your design-
J. Baker

[AviatorJ]

I fly with a stand alone GTN 650 in my current plane. By itself it has a lot of functionality so much that I'm not even full aware of what I'm missing out on by not having an ADAHRS or Glass Panel of any type. By itself I use it as my sole IFR Navigator. When having some hand flying fun in IMC it's included in my scan and will fly a full approach on it.