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05-10-2018, 12:28 AM
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Join Date: Oct 2017
Location: bellingham, wa
Posts: 202
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I will be ordering an EFI in a month or two, but I have spent more than 6 months trying to figure out how I want to wire it. My "dream" was to use an automotive relay and fuse panel. That is still my long term goal that may not be attained. My second choice was an aftermarket panel, which I now possess and am wiring up. Hopefully in the next few months I will have the time to figure out how to create a professional looking electrical system on a PC. Right now, not so much.
I am using a "Severe Service Vehicle" relay panel. Meant for construction equipment, off road vehicles, etc. All primary circuits will operate off of SPDT terminal 87A in their primary mode. NO relay operation required to run the engine. I will have a bank of micro switches to energize the relay coil and switch the relay to terminal 87, which will shut off the circuit. These switches will allow me to shut off fuel pump 1 or 2, ignition 1 or 2, or alt 1 or 2. If any or all of these switches, or their power source fail, no problem. The engine runs. They exist to check the function of the backup, or select the backup. Each function has its own circuit. No A/B switches.
The panel uses Delphi sealed connectors, and the whole panel is IP 66 or 67 for moisture and vibration. it is a little heavier than I would like at 3 pounds. But compared to a bunch of bus bars, etc, it might be a push. Maybe 550 to 600 bucks with all connectors and wire.
The power to the panel will comply with one of Nuckols wiring schemes.
Hopefully I get automotive reliability, with the ability to test backup functions, or switch to the backup. Like I said I would prefer to use a stock auto panel, but I haven't found one that I could easily switch functions "off" to check the backup.
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05-10-2018, 09:59 AM
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Join Date: Jul 2014
Location: West Covina, Ca
Posts: 52
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Parallel diodes
A few pages ago I proposed paralleling diodes to put two batteries in parallel, hopefully making an engine bus more reliable. I was able to put the question to an automotive electrical designer. Here is his resopnse, which will definitely change my thoughts:
"I am suspicious of parallel operations. I have tried paralleling power supplies, coils, and transistors and due to imperfect matching things get hot due to oscillations: on and off and the switching causes heat. Getting the parallel devices to conduct equally is not easy. It also does not offer the same safety factor as having tested redundant components that can be switched out and in as needed. Some math analyses would be needed to verify this.
Another concern is that diodes can fail either open or short. I am not sure and will do some more thinking about the impact of a shorted diode. An open diode by itself would not be a problem, other than being able to detect and replace when back on the ground. What is not wanted is one battery draining into the other; one or both batteries might fail. To me a switching arrangement would be better. That is switching in and out either power system to either critical component set. The best would be on the ground checks, before air, of both power systems and both sets of critical components and then the capability of switching."
__________________
Cliff Langlois
Meridian, Idaho
Cliffsrv10.blogspot.com
Project Sold 9/2018
RV-10
Empennage finished!
QB Fuselage and wings in hand
Taking a bite of the elephant every day.
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05-10-2018, 11:18 AM
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Join Date: Jan 2008
Location: Ashland, OR
Posts: 2,574
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Quote:
Originally Posted by rcpaisley
"is there no point inside that box where a single failure (bad solder joint? bad circuit element? metal chip? high-velocity projectile penetration?) can cause the essential bus to shut down? No place?"
The Bus Manager is plenty good enough for me to fly behind and I'm pretty picky about what keeps me in the air. And it's way better than any home brew solution I've ever had the privilege of reviewing. Our professional installers who have lots of experience with these parts use a Bus Manager - as do we.
Robert
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That may be so. But it doesn't answer my question. How can you claim this to be a redundant system (triple redundant on your website) when its all in one box?
The "home brew solution" you are casting shade on is two switches and two diodes.
__________________
Steve Smith
Aeronautical Engineer
RV-8 N825RV
IO-360 A1A
WW 200RV
"The Magic Carpet"
Hobbs 625
LS6-15/18W sailplane SOLD
bought my old LS6-A back!! 
VAF donation Jan 2020
Last edited by scsmith : 05-10-2018 at 11:21 AM.
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05-10-2018, 11:33 AM
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Join Date: Apr 2008
Location: Riley TWP MI
Posts: 3,070
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Cliff, what your automotive electrical designer said about parallel diodes and etc is true. However, from what you wrote, it seems that he was trying to share the load between two parallel devices, not easy. But if each of the diodes is capable of carrying the full load independently of the other, then I see no problem of having two in parallel. I am not necessarily recommending two diodes in parallel, just saying that doing so does not create a problem. Mount diodes with heat conductive paste to help carry the heat away, and they should last a very long time.
__________________
Joe Gores
RV-12 Flying
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05-10-2018, 03:43 PM
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Join Date: Jan 2008
Location: Upland, CA
Posts: 286
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Bus Manager
"That may be so. But it doesn't answer my question. How can you claim this to be a redundant system (triple redundant on your website) when its all in one box?"
Steve,
There are multiple current paths through the box - four as matter of fact.
Two from the batteries going through the internal normal ops bus relays and two through the emergency power switch.
Maybe we should call it "quad redundancy"?
The fact that "everything is in one box" is irrelevant. Everything in your plane is in one airframe - does that mean that nothing in it is redundant?
Robert
Last edited by rcpaisley : 05-10-2018 at 03:44 PM.
Reason: sp
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05-12-2018, 05:59 PM
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Join Date: Aug 2010
Location: Newport News, Va
Posts: 325
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Bus Manager pump SPOFs
Quote:
Originally Posted by rcpaisley
... with Bus Manager... it's pretty hard to have the engine turn off unintentionally.
Robert Paisley
EFII
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I lost faith in Bus Manager when I saw it recommends both pumps share common wire and relay.
https://drive.google.com/file/d/1Sbe...ew?usp=sharing
Last edited by johnbright : 07-31-2019 at 01:06 PM.
Reason: EFII updated to dual breakers
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05-13-2018, 09:50 AM
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Join Date: May 2010
Location: Baton Rouge, La.
Posts: 753
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Quote:
Originally Posted by johnbright
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That?s an easy workaround. It?s simple to split that circuit up and incorporate two relays and two C.B.?s....that?s what I did. You can wire up any of the peripheral devices any way you like. In my case I?m incorporating two relays and two C.B.?s and I?ll let one toggle switch control the pumps...(off/(pump1/auto)/pump2. If you notice in the B.M.?s wiring schematic it doesn?t call for an off switch. If you follow those wiring directions exactly as shown it would have you pulling the breaker to turn the pumps off. I don?t like that aspect of the system so I have a three position toggle switch to give me better control of the pumps. Another example is the battery wiring. I?m using two batteries in my setup but only one of them will ever be used for starting and the other one....(which will be one of the smaller and lighter EarthX batteries)...will only be in place for redundant/backup power. This will allow me to not only remotely mount the backup battery but also limit its wire size (maybe 8 or 10g) because it won?t be being used for starting power. Also, doing it this way will allow me to eliminate the two starter solenoids that the schematic calls for. I plan on wiring the main battery cable directly to the starter and just using the starters own built in solenoid to engage the starter and this will all be done via the main/ battery/momentary start switch. The main point I?m trying to make in being a proponent of the bus manager is that if you take advantage of its primary function....which is to ?manage? your main and E-bus, you can then customize other aspects of it as you see fit. For me, I really like the fact that it can manage a led-acid and lithium battery together within the same system...which is typically a no-no. It allows for easy operation of batteries one ?or? two, or battery one ?and? two.....your choice of how to wire up your system. Another feature that I like is the automatic switching of fuel pumps 1 and 2 in the event of a sudden fuel pump failure/stoppage. I could go on and on about what I like about the bus manager but I think I?ve made my point. I think that if you look at its base/core function and architecture, it?s a box that works pretty well. I think that it?s fairly easy to modify and customize how the B.M. interacts with the rest of your wiring system and components. Could it be better and maybe even fool proof?....maybe so, but like I said, if you use it more for it?s base function and let it do it?s job, than I think it?s fairly easy to do any other modifications to your own personal wiring architecture that fits your personal needs. There are a lot of people here on the forum that are wiring gurus and I?m sure that they can design a wiring schematic that?s way better then the bus manager, but for a dummy like me I think it help me avoid a lot of mistakes that I could potentially make. Man, I didn?t intend on this post being this long when I started writing it. LOL!!
Mark
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05-13-2018, 11:11 AM
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Join Date: Dec 2007
Location: Dogwood Airpark (VA42)
Posts: 2,597
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Careful
Quote:
Originally Posted by Mark33
SNIP.... Also, doing it this way will allow me to eliminate the two starter solenoids that the schematic calls for. I plan on wiring the main battery cable directly to the starter and just using the starters own built in solenoid to engage the starter and this will all be done via the main/ battery/momentary start switch. .....SNIP
Mark
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Recommend you retain the start solenoid, not just wire directly to the starter from the battery.
Don?t forget you will need to get the alternator charging current to your start battery. While you can connect it directly to the battery side of your start solenoid, you then have no way to disconnect it. If you connect it via your smaller relays for the other bussses, you will overload them (60+ amps is a boatload).
This leads to the logic for having a conventional master relay(s) between the battery(s) and the start solenoid.
On my planes the POH immediate action for any electrical fault is to open each battery master solenoid as this will isolate the most likely problems. The panel has separate 30 amp relays feeding power from each battery to that half of the panel so IFR flight continues as the pilot figures out what happened - or just lands to figure it out on the ground.
Carl
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05-13-2018, 11:17 AM
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Join Date: May 2010
Location: Baton Rouge, La.
Posts: 753
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Quote:
Originally Posted by Carl Froehlich
Recommend you retain the start solenoid, not just wire directly to the starter from the battery.
Don?t forget you will need to get the alternator charging current to your start battery. While you can connect it directly to the battery side of your start solenoid, you then have no way to disconnect it. If you connect it via your smaller relays for the other bussses, you will overload them (60+ amps is a boatload).
This leads to the logic for having a conventional master relay(s) between the battery(s) and the start solenoid.
On my planes the POH immediate action for any electrical fault is to open each battery master solenoid as this will isolate the most likely problems. The panel has separate 30 amp relays feeding power from each battery to that half of the panel so IFR flight continues as the pilot figures out what happened - or just lands to figure it out on the ground.
Carl
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Great points!!
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05-13-2018, 11:23 AM
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Senior Curmudgeon
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Join Date: Sep 2005
Location: Dayton Airpark, NV A34
Posts: 15,420
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Quote:
Originally Posted by Mark33
That?s an easy workaround. It?s simple to split that circuit up and incorporate two relays and two C.B.?s.... and I?ll let one toggle switch control the pumps...(off/(pump1/auto)/pump2.
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If you are running dual feeds and CB's, and switching with a toggle switch, why would you need the relay at all?
In the linked schematic the relay is used to switch from one pump to the other while using a single feed from a single CB.
__________________
Mike Starkey
VAF 909
Rv-10, N210LM.
Flying as of 12/4/2010
Phase 1 done, 2/4/2011 
Sold after 240+ wonderful hours of flight.
"Flying the airplane is more important than radioing your plight to a person on the ground incapable of understanding or doing anything about it."
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