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Power Distribution Panels

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  • Power Distribution Panels

    Have any of you used (or know of someone who has used) one of these power distribution panels (by Composite Design)?

    I've read some good reports elsewhere: Zenith builders forum (appears to be a standard kit component) and on VAF (one positive review, no negatives). They seem to be well made from solid components, and although they use automatically-resetting circuit breakers (which I wasn't very happy about), the designer tells me the CBs in question will NOT reset if the circuit is shorted out, or is still drawing high current. Some reasonably positive comments on the AeroElectric Connection (with no dramatic rebuttals by the experts there) sent me in this direction. The company owner is extremely responsive, and if you call him, he explains how everything works and how it should be wired up quite well. And the "consumables" (CBs, switches, etc.) are all replaceable without major headaches.

    These power panels initially seemed a bit pricey, but as I added up the costs of the various switches, circuit breakers, bus bars, etc., it looks like I would only save about $100-150 doing it all myself, and would still need to do all the design, mounting, labelling, and "behind the panel" work to get to this stage. Seems like a reasonable tradeoff to me, especially given the "neatness" of the resulting installation. (Some of the same reasoning I used when I purchased the QB+ Patrol kit from Mark G...)

    I'm most interested in their "LSA Power Panel" (2.375" Tall x 10.5" Wide x 6.5" Deep), versus the "Standard Power Panel" (2.25" Tall, 13.0" Wide, 7.75" Deep). The "standard" allows for 80 Amp alternators (vs 60A for the LSA), and adds a Pitot Heat switch and a "Spare" switch, plus a few additional circuit breakers (pitot heat, avionics spare, trim/autopilot, and an additional general-purpose "spare" as well). But since the LSA panel has switches for Master / Alternator, avionics master, landing, strobe and nav lights, plus a fuel pump, I think that's pretty much all I would need. (My panel will be VFR, and if I ever add a heated pitot tube, I can add the switch and CB for that reasonably easily. The CBs also seem to cover everything I would want, even if I added a 2nd EFIS, 2nd Nav or Com, etc.

    They also offer a "mini" panel that is smaller, and comes in a separate package, in part because it uses a separate Master/Alternator switch/CB panel (which he is nice enough to include with the mini). But it does not have a fuel pump switch, not the two dedicated CBs for EFIS-1 and EFIS-2 – you would probably consume the "Spare" CB for a single EFIS, and I'm not sure what you'd do if you had a second EFIS.

    There's also a repackaged version of the LSA panel that fits in a standard avionics stack, and is 4.25" tall... They basically stack the switches above the circuit breakers. Basically the same real estate on the panel, but narrower and taller...

    Here are links to the descriptions on the Composite Designs website:

    And here's a picture of the LSA Power Panel (front/top view):

    LSA PP Front.png

    And here's one of the "guts" of the same panel. You can see how the CBs and switches are mounted to the rack, and easily replaceable. You can also see the well-labelled "ring terminal" connectors for all of the external connections.

    LSA PP Internals.JPG

    So, any thoughts or inputs?

    PS - I forgot to mention that this system also has a provision for a backup battery, with automated charging and engagement when the main power sources (alternator and battery) lose power. It's a $125 optional board that you add, plus a 7-10 Amp/Hr battery. They offer a 7AH battery for $40.
    Last edited by JimParker256; 10-31-2019, 12:06 PM.
    Jim Parker
    Farmersville, TX (NE of Dallas)
    RANS S-6ES – E-LSA powered by 100 HP Rotax 912ULS

  • #2
    If there are no single failure modes that can take the whole unit out, I say go for it. That is my complaint about Vertical Power which is, if I understand correctly, more of a black box that controls all power.


    • #3
      That looks plenty reasonable to me. With the exception of the radio filtering, It's nothing more than what you would wire yourself except with a circuit board and tray to make it easy. The additional battery deal is nothing more than a diode/relay/both, so again, nothing you couldn't do yourself, just simpler and faster.

      I would consider it myself, however, I don't like the switches they used. I prefer the S700 switches from B&C as they won't have any trouble switching a 10amp load a LOT of times. I also like fuses instead of breakers as they are lighter, cheaper, and more reliable.
      People argue that: I argue that:
      Breakers let you troubleshoot Don't troubleshoot in the air, land first
      Breakers let you isolate things Install a switch if you want that
      You can see when a breaker pops Install an illuminating fuse
      Breakers are reliable They don't maintain the same rating after being cycled a bunch of times and can get flaky. Blade fuses are EXTREMELY reliable.

      Anyway, if you want fuses, and don't want a rat's nest, and like the circuit layout, and don't find the panel to be ugly, then I'd say it's a find!



      • rodsmith
        rodsmith commented
        Editing a comment
        I was going to mention my preference for fuses, but that is an individual decision, and this panel will save a lot of work for those interested.

      • JimParker256
        JimParker256 commented
        Editing a comment
        In general, I prefer fuses – especially the automotive-type blades that illuminate an LED when they "blow". It was trying to find a decent fuse block that didn't take over the entire panel that got me started down this path... Well, that and the absurd cost of decent switches!

    • #4
      I'd seen these before but forgot about them for my design. Looks like a nice kit though, could save some time. I'm in the fuse camp too.
      Dave B.


      • #5
        I think that is a smoking deal and will save you a lot of time. If I wasn't using EFI, I would do something similar.
        I also prefer fuses over CB's, but on a fairly simple aircraft, a CB won't take out anything that turns you into a glider pilot.


        • #6
          I am using a different type of power distribution module. I am using EFI, which has 2 of everything so I needed quite a few circuits to switch. I have had quite a few CB's go bad in aircraft, and they were the best money could buy save the Space Shuttle. I have also had a lot of switches go bad, both in aircraft and cars/boats/etc. I think I have only replaced automotive relay in a car once or twice in 40 years. That doesn't include starter solenoids, which I have had go bad.

          The panel I am using has 2 separate busses and all dual pole relays. Under "normal" flight conditions, the only relay that will be energized is the master battery contactor. The rest of the relays will be in their resting, or non-energized position. They are only there to turn something off, or the backup on.


          • #7
            Do you feel the relays add anymore weight than a circuit breaker and switch? How does the relay trip and provide safety for the wiring harness? Do the relays have current protection ratings ?


            • svyolo
              svyolo commented
              Editing a comment
              2 separate busses. Each bus has 12 circuits, all with their own fuze. Each bus has 8 switched (relays) and 4 unswitched circuits. Plus 4 additional unswitched and 2 switched circuits not attached to either bus. It was made to be the electrical system for a vehicle, and is IP67 rated.

              The relays are all automotive micro relays. The whole panel weighs about 2.5 pounds, similar to VPX.

              Similar to the Jim's panel, and the VPX, it greatly simplifies wiring. In my case I believe the connections are all etched copper, instead of wiring. All the switches in the panel (not very many) simply energize the relays. In the wing root I have some rocker switches that switch power without going through this panel. Other than that, everything goes through it, including the start switch.

              EFI has 2 fuel pumps, two coils, 2 computers, and 2 of a bunch of a few other things. It needed its' own bus, and several of those items needed to be switched so I can do a Mag check, fuel pump check, etc.

              Otherwise I would have gone with a panel like Jim, who started the thread.
              Last edited by svyolo; 10-31-2019, 08:12 PM.

          • #8
            I looked at their website, they don’t list their MTBF statistics. Of course many manufacturers don’t. My RV has too much technology installed and I am waiting for something to quit. Is there a way to get home or to someplace for repairs if the component fails I think is a fair question and design goal. I think my Patrol will have the technology of a 54 Chevy. maybe the whole VPX process has left me wondering about future support and aviation technology or then again I might just be a Luddite. I look forward to reading about your success with this product.
            Scott Ahrens
            Bearhawk Patrol Plans Built


            • svyolo
              svyolo commented
              Editing a comment
              I would have preferred to use a panel from a newer car to run the fuel injection, but they didn't have any provision to switch things on and off. Other than being able to switch things on and off, the panel I am using is similar to the way pretty much every car has been wired for probably over 30 years.

              Maybe brand new cars and high end cars are all electriconic CB's, but I have 3 cars less than 3 years old and they all have relays and blade fuzes.

              I wasn't ready to go the VPX route as I only have 1 EFIS. Maybe next time.
              Last edited by svyolo; 11-01-2019, 11:21 AM.

          • #9

            In your post/comment numbered 3.2 you mention that you prefer fuse blocks, but you are concerned about the panel real estate that the fuse blocks would consume. In your post #1, you compare the cost of the Power Distribution Panel with a panel that has CB's, not Fuse Blocks.

            I will offer another data point.

            I learned from Bob Nuckolls that only one CB/fuse circuit should be planned on being reset... the Alternator Field CB. I cant think of another CB that should be reset. Not the strobe, nav light, or radio, or fuel boost pump. If it pops, trouble shooting at the completion of the flight is called for.

            So, I submit the opinion that a single panel mounted CB for the Gen. Field and remote mounted fuse blocks (instead of a panel mounted fuse block) might satisfy all of your concerns about panel space, quality, reliability and cost.

            Using the Blade type connectors like the Power Panel has for connections to the CB in an electrical system makes it to easy to fabricate/assemble.
            Brooks Cone
            Southeast Michigan
            Patrol #303, Kit build


            • JimParker256
              JimParker256 commented
              Editing a comment
              Brooks, you're right about Bob's opinion on resetting CBs in flight (or any "in-flight" electrical troubleshooting, for that matter). I agree with both of you, and have no real desire to reset a circuit breakers (or fuse, for that matter) in flight. The CBs in his power panel will not reset as long as the circuit remains "shorted". Searching Bob Nuckolls' archives, he seemed to be OK (if not particularly thrilled) with that approach.

              If the power panel above had blade fuses, it would be exactly what I want. I'm actually planning to write the designer to ask if he would consider offering that as a new product in his lineup.

              And I also agree that the fuse block does not *need* to be on the panel, just needs to be "reasonably accessible" on the ground. But as I'm getting older, reading glasses make it increasingly "less fun" to try to duck under the panel to check / replace fuses – or much of anything else. (And let's not even talk about lying on our backs working overhead under the panel...) So I'm trying to design my panel so that everything is reasonably accessible from the front, after removing the EFIS screen. A buddy showed me that on his plane, where he oriented all the connectors, etc. so they can be accessed working through that large hole left after removing the EFIS. I thought that was pretty slick. (Unfortunately, I didn't take any pictures.) But that doesn't help when it comes to checking the fuses before flight, with the system engerized, etc. For that, it would be much simpler to have them on the panel.