---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Sat 08/04/18: 3 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 06:43 PM - Power (Adelk123) 2. 07:02 PM - Re: Power (Robert L. Nuckolls, III) 3. 09:10 PM - Re: Power (Adelk123) ________________________________ Message 1 _____________________________________ Time: 06:43:18 PM PST US Subject: AeroElectric-List: Power From: "Adelk123" Ive got a question for the group. Im currently powering dual board ECU through a DPDT switch with each side of the switch switching different power sources. Ive decided I dont want to use two different power sources for the ECUs. I prefer to just power the ECUs directly off of my engine Bus. This bus is an always hot battery bus mounted at the aft end of the Aircraft. With the floors being closed up, access is challenging but not impossible. I had considered the idea of each ECU having its own circuit powered off of the same bus. I am currently out of additional circuits on that fuse box though. I have considered combining with a circuit that I can readily access. I have two small led baggage lights powered off of that same bus that I could tie in to fairly easily. If there is no real benefit to having two circuits on the same bus due to the switch still being a single point of failure, would it be acceptable to stack the terminals on one side of the switch to power both ECUs from one source? The current for both combined is less than 1/2 of an amp. I realize that doing so still creates a single point of failure so Im looking for advice finding a solution that I might not of already thought of. Thanks for any advice. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=482061#482061 ________________________________ Message 2 _____________________________________ Time: 07:02:29 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Power This bus is an always hot battery bus mounted at the aft end of the Aircraft. With the floors being closed up, access is challenging but not impossible. I had considered the idea of each ECU having its own circuit powered off of the same bus. Depending on how 'orderly' the lay of wires is in the bundle carrying the current feeder, it may be possible to lap solder TWO wires to the end of the single wire thus converting the single wire into a 'tag line' for installation of a new pair. I am currently out of additional circuits on that fuse box though. I have considered combining with a circuit that I can readily access. I have two small led baggage lights powered off of that same bus that I could tie in to fairly easily. Use one of those . . . separating them eliminates the single point of failure for one ECU (or intermediate wiring faults) from tripping both systems off line. If there is no real benefit to having two circuits on the same bus due to the switch still being a single point of failure, would it be acceptable to stack the terminals on one side of the switch to power both ECUs from one source? The current for both combined is less than 1/2 of an amp. Your choice . . . but I couldn't sell that idea onto a TC aircraft. I presume you currently have a 2nd source on a bus up front? I think I'd leave it there. The 'plum' in your FMEA pudding is the exceedingly remote probability of loosing BOTH sources during the consumption of ONE tank of gas. Exactly what those sources are is irrelevant as long as they too do not suffer a 'cow pie' in their FMEA. This leaves JUST the switch which, in an OBAM aircraft, will see perhaps a couple hundred actuations per year . . . at your stated load, the electrical life is infinite. The mechanical life will be more environmentally driven than service driven. I'd just replace the switch for grins every 5 years or so . . . I've seen more switches (even the $high$ mil-spec devices) fail due to chronological AGE in a less than pleasant environment than from service life . . . Bob . . . ________________________________ Message 3 _____________________________________ Time: 09:10:48 PM PST US Subject: AeroElectric-List: Re: Power From: "Adelk123" Ok, thanks for the feedback. Yes, I currently have the secondary ECU powered another bus in the front of the airplane. What I failed to think out completely was the load shedding side of things. My intent was to have the ability to load shed everything except the critical engine items, the second ECU not being critical. The problem is the switchology has become more complex than I like due to the injector relays and their relationship with the ECUs. I feel its a safer and a more simplified solution just to have the same power source with both ECUs and leaving no possibility to inadvertently shut down the engine during load shedding. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=482063#482063 ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.