Electrical help needed
 

I am ashamed to admit that I have relied too much on my previous build partner and to this point have not used a tech counselor. I am at the point now where I need to install my panel. I feel lost. I know that I need to run wires and make harnesses but I don't really know how to do that. Is there a tech counselor or perhaps a builder near me that would be willing to help?

To some extent the show must go on. So a few questions:

Do I connect the master switch directly to the battery contactor? And does the other side of the wire connect to a piece of metal, which we can call a buss?

Do the circuit breakers each connect directly to the buss created above and the other wire to the component for the circuit breaker?

I have an IO-390A motor and I will have an electronic engine instrument setup in the EFIS. I will need to run wire to the motor for the instruments. How many wires should I plan to run from the MFD to the motor? Suggested length (longer is better and I will trim later)? Are red and green wires OK to use? I am thinking red for positive and green for negative.

I have decided to go with the Cummins Battery - 31, 950 CCA STUD Battery. I need to build a tray for it, but I am not sure how to determine whether the tray is sturdy enough? Is there some basic formula that I can use to determine how strong to make the tray? The battery weights 82.5 pounds and I am just not sure how to reenforce that weight onto a tray and have the tray be able to withstand the weight. Due to weight and balance I am planning to put the battery under the baggage floor, which is causing me some wiring planning troubles because I need to have a place to run the wire bundles from back to front. What have others done? Should I elevate the battery and run the wire bundle underneath the battery?

I think that this is all I've got for now. I am at a point in my build where I am feeling frustrated and a bit paniced because I feel like I am in over my head. But I have come this far, so I realize I am probably not as in over my head as I feel like I am. However, I do think a tech counselor is needed at this point.

82.5 lbs...now THATS a battery:D
Cheers,
DaveH

Useful reference
 

This "how to" book (the Aeroelectric Connection) should be helpful and provide the answer to many questions and things you need to know:

https://www.aircraftspruce.com/catal...roelectric.php

wow
 

I snortled and sprayed my coffee on my keyboard! :D

Here's a great source of electrical information for homebuilt aircraft: http://www.aeroelectric.com

An 82 pound battery has no place in an RV - except maybe the kind with 4 or more wheels that includes a shower and toilet.

I'm dubious about the seriousness of your post. If you're building an RV-14 and feel like you're in over your head, why not read the plans and use the wiring diagrams, harnesses, battery tray, and battery that are part of the RV-14 kits?

Van's has a technical support line as well - might be a good place to start if you are serious about building a safe airplane.

You are! I will restrain from further commenting, but will advise that you not undertake this kind of departure from the plans without a mentor. Your post strongly suggests that you NEED a partner with more experience than you. I suggest finding a new one.

Larry

Earl,

In one of your other posts you mentioned that you were receiving guidance from EAA1441 members. Maybe that would be a great place to start?

https://vansairforce.net/community/s...6&postcount=14

Buy the Aeroelectric Connection and Aircraft Wiring Guide books. It will get your head wrapped around basic architecture of your primary electric system.

Stick with the plans and don't install that battery - rediculous. Use what the plans call for, in the place it calls for.

Aeroelectric Connection
 

FYI:

Latest Aeroelectric Connection book free PDFs are at http://www.aeroelectric.com/Books/Connection/

Latest revs of Z dwgs are in the folder called "Adobe_Architecture_PDFs/" at http://www.aeroelectric.com/PPS/ There are updates since the book came out.

Bob Nuckolls and others answer questions on the Aeroelectric List hosted by Matronics.
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Can you suggest a battery with the same cold cranking amps but weighs less? My last RV had problems with warm starts due to not having enough power in the battery. It would die if you turned the prop over very much at all. The primary cause was the small battery, and my fix is a battery with higher amperage ability.

The plans for the RV-14 are not that easy to read. They are single pages with part numbers and measurements on them but I am having a hard time turning those things into reality. They are not 3D. Up to this point, Hal was reading and interpreting the plans and I would do as he instructed. But I have lost Hal.

I did not know that the kit included wiring harnesses for the avionics and switches. I have been working off of the assumption that those are custom to the builder and therefore not included in the kit. Can you point me to a part number or something I can use to find the harnesses?

It is a small chapter with no technical counselor available. And nobody has built an RV 14 series airplane. The suggested battery came from a 1441 member, but it is being shot down here. We are all doing our best with what we have.

Thank you. I began reading about a bussbar last night and will also read Aeroelectric's words on them too.

Are most builders using copper for the bussbar? Is it easiest to run it along the bottom of the instrument panel, along the length of the panel going across? Do I need to worry about welding the screws to the bussbar if the correct metal isn't used for the screws? If so, what is the ideal metal for the screws?

Mentor
 

Hi Earl,
Sounds like you are trying to get it completed without any personal hands on help. These questions really cannot be answered appropriately on here as we don’t know what you are working with as far as materials, tools and any modifications that have been done to the airframe at this point. I HIGHLY suggest you get someone on board as a mentor or another partner to help you finish it up. If there are no EAA techs available then you could always call around and find a experimental friendly AP to come have a look. My 2 cents, be safe

Sounds like a wiring problem to me.

Gee, Bob Nuckolls says in chapter 5 on grounding: "If I had my fondest wish for ultimate performance in an aircraft electrical system, the battery, starter and alternator would all be within 1 foot of each other! Interestingly enough, Van's RV series airplanes come closer to that goal than most kitplanes. RV batteries are... with starter and alternator just an engine length away."

Ref also chapter 2 on batteries... paragraph heading "Engine Cranking".
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Tech Counselor
 

Earl,

There appears to be several within a 50 mile range of your zip code:

https://www.eaa.org/eaa/aircraft-bui...ical-counselor

wow...
 

I have no words...

EAA Resources
 

I found that the EAA Sportair Workshop for electrical helped me, though they are paused for COVID. This workshop is 2-days long, and the video in the link illustrates the hands on training they provide.
https://www.eaa.org/Shop/SAW/Worksho...stems_avionics

EAA's hints for homebuilders videos viewed online are free to EAA members:
https://www.eaa.org/videos/hints-for-homebuilders

SteinAir has some helpful videos on wiring techniques:
https://www.youtube.com/playlist?lis...Hqdp8lReIJ0XBw

Besides the RV-14 plans there are other basic wiring plans available from Van's in the OP drawings, like OP-10, OP-12, OP-30, OP-31. Even though they are for other airframes the concepts should help.

In addition to those resources, most electronics vendors, for the major panel electronics, have detailed installation manuals for their equipment.

Dave

82 pounds? That's about 3 times the weight of the battery in my car, and my car needs enough juice to start a V-10 engine.

That's 12 pounds more than my Field Labrador Retriever.

I'm planning to use an Earth-X battery in mine - and I will have the 6 cylinder -540. I think the -900 weighs about 5 pounds.

Earl:

As you can see from my signature, I built and flew an RV-14A. My recommendation remains the same: use the standard battery/tray and wiring for battery/starter. They work just fine. Van's supplies the basic wiring in the kit and includes mounting points for master contactor and starter relays as well, along with very good wiring instructions/diagrams.

I found the RV-14 plans to be exemplary and not at all difficult to read/understand, and I'm not at all sure what you mean by saying "not in 3D", since many of the plan drawings include perspective that is indeed 3 dimensional.

In another thread regarding your rather extreme claim (and pride in same) of exceeding VNE in your airplane, a poster suggested a safety stand-down. I suggest the same for you as a builder, as others have said. Before continuing building your airplane you need to build a basic understanding of aircraft structure and safety as it relates to aircraft structural design and integrity. Not an engineering degree but enough to understand why it might be a very bad idea to mount something very heavy inside aircraft structure not designed for the weight. Are you aware that not only would an 82 pound battery mounted below the baggage floor virtually take up all the weight allowed in that area, you would have no way to access it in the future (the baggage floor is RIVETED to the baggage ribs!) AND you would be mounting it on structure (external aircraft skin) not intended to bear the weight? (This assumes you could somehow fit this battery between the baggage ribs, floor, and fuselage skin).

Regarding your other questions - I will make no suggestions in that regard. You need to walk before you run. Get the knowledge and skills you need, and appropriate assistance from someone who has the same, before proceeding with building an airplane. Learn how to read and interpret the plans. Learn the basics before moving on to something like electrical design and installation. You don't get extra chances to do it right.

Thank you for the assistance everyone.

I am but just a student. I've exceeded VNE on accident but truthfully, I bet most of us have. It happens, and the trick is to not let it happen too often or happen again.

After consulting with others I am going to keep this one simple. A master switch connected to a busbar, and lights on that busbar. Foregoing the avionics master and will just turn off the radios manualy at the conclusion of the flight. I will connect the radios to the battery directly for redundancy.

Regarding the battery, it is true that the baggage floor is riveted, but I am planning to use quarter turn screws for ease of access, inspection and so I can install the battery where it works from a C.G. standpoint

Did you understand the part about the structure of your airplane not being designed to bear weight UNDER the baggage floor?

I stand by my earlier suggestions including that you stop building until you have expert help and more knowledge/skills.

Again, we get sucked in with a request for help and your reply is "thanks, but I'm sticking with my idea." This will be my last reply to you.

Larry

You folks have taken the bait once again, hook, line, and sinker.:D

yup!
 

Or, as the Brits would say, "someone has been pulling my plonker"!

Catfish:
verb (used with or without object)
Slang. to deceive, swindle, etc., by assuming a false identity or personality online:
“He fell in love with her online before he realized he'd been catfished.”

I too read the initial plea with much skepticism (especially given the comments in other threads by "Earl") and hence limited my advise to simply seek local help. We'd all be remiss as a community if no advice was offered. That being said, seeking advice in earnest on this forum and then disregarding it categorically seems to fit the definition of "trolling".

I admit to taking the apparent trolling bait but I recall some similar threads/discussions involving a guy who was all too real and just as obstinate in his acceptance of advice (which was all good). Sadly he died when he crashed his plane. So I'd rather be a fool who tried than a bystander who did nothing.

Very well said.

I have a tendency to extend the benefit of the doubt to people, occasionally to my own detriment. I'll take this thread at face value and won't make any assertions about the sincerity of the request for help or assumptions that the advise will be heeded. There has been good input here, I'll add mine for what it's worth.

I had some electrical issues with my plane soon after completion and had some here suggesting that I stop and get someone who knows what they're doing look at my work. That's a reasonable statement and one that I couldn't argue against given that the problems that I was having were entirely my own doing. I too did not have anyone nearby to assist and managed to resolve my issues with help from this group and from my avionics manufacturer.

I had problems starting my plane at first, I blamed the battery (PC680). Didn't seem to have enough juice to crank well. I ended up putting in a Shorai Lithium Ion battery which worked better but was not a full solution. On a flight into a small unserviced strip last summer I lost my ability to start altogether. I soon found that my starter cable had burned through. My problem starting was never the battery, it was the use of a homemade 8 GA cable for the starter contactor to starter cable. I replaced it with a prebuilt 4 GA cable and suddenly I was starting better than ever. I replaced 2 more cables when I got home. This only caused me an inconvenience, but it could have caused a fire.

I said all that to make one point and make it loudly. Put your battery as close to the starter as you can and use heavy cable for your connections. If you place it in the back, the proper sized cable to the starter (0 GA or larger?) could weigh as much as a battery. That sort of distance negates the more powerful battery, you'll get better cranking power with a small battery with a short run. And you might just save enough weight to be able to fill your tanks with a passenger and baggage.

Once more - DO NOT under size your primary power cables. It is asking for a fire. Over sizing your battery will make it worse.

I will also recommend the SportAir workshop, it was most helpful. I can't imagine the mess I would have made without it. Hopefully it gets restarted soon.