---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Wed 06/03/20: 2 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 08:12 AM - Re: Looking for help finalysing my Cozy's electrical system (johnbright) 2. 08:34 AM - Re: Re: Looking for help finalysing my Cozy's electrical system (Robert L. Nuckolls, III) ________________________________ Message 1 _____________________________________ Time: 08:12:32 AM PST US Subject: AeroElectric-List: Re: Looking for help finalysing my Cozy's electrical system From: "johnbright" Re v1.04 and v2.11 Hi Eric, I mis-spoke about switching power to EB 1 and EB 2 with relays to meet FAR 23.1361. You already meet FAR 23.1361 with the two battery contactors. When I was considering Z-14 for my SDS EFI+I equipped RV-6A, I wanted to be able to kill both battery contactors in a smoke in the cockpit situation and still have the engine running: This led to an always hot engine bus diode OR'd from both batteries. If you would like to reference my Z-14, it is called "Electrical Schematic RV-6A with SDS dual EM-5-F rev G" in the Archive folder of my files. SDS requires coilpack power to be switched whereas EFII has the P-lead input to the ECUs. For FAR 23.1361 you could leave the P-leads unconnected and relay switch the coilpacks. The always hot nature of the engine bus and the items attached to it that are not relay switched presents a danger in service and crash scenarios. With Z-101 the only thing always hot that's remote from the battery is the backup alternator and one could choose to add a relay to it. -------- John Bright, RV-6A, at FWF, O-360 Z-101 single batt dual alt SDS EM-5-F. john_s_bright@yahoo.com, Newport News, Va https://drive.google.com/drive/folders/1u6GeZo6pmBWsKykLNVQMvu4o1VEVyP4K Read this topic online here: http://forums.matronics.com/viewtopic.php?p=496617#496617 ________________________________ Message 2 _____________________________________ Time: 08:34:09 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Looking for help finalysing my Cozy's electrical system At 11:39 PM 5/31/2020, you wrote: > > >Single points of failure: >All four injectors are powered by one reley, wire, and fuse link. >Both pumps are powered thru the same switch. Agreed. Will the engine run if one injector becomes inop? Suggest separate switches for each fuel pump. Ditch the 'auto' feature' >Questions: >The injectors have fuse links in the harness. Are they sized so they >won't pop the one fuse link that feeds all four injectors? >What happens if both injector enable inputs are un-grounded? >Why are there relays for removing power from the coils? Strive to reduce relays to minimum. I recall seeing this installation published somewhere. http://aeroelectric.com/Pictures/Misc/Too_Many_Relays.jpg . . . mind boggling. >What is the EFII Syst 32 Inj Pwr Module? I would have thought each >ECU box has open collector injector drivers inside. >Will the automatic aux pump feature result in a relaxation >oscillator? (No pressure, pump on... now we have pressure, pump off, repeat.) >Where are the batteries located? >Thoughts/IMO: >It would be simpler to have separate toggle switches for left and >right coil "P-Leads". Agreed >It wouild be simpler to have an SPDT switch for injector enable >grounds like EFII illustrates but what is the effect if the ground >is lost to both injector enables? Something to sort out . . . potential single point of failure. >I don't know how to have faith in Bus Manager (I know you mentioned >you are not using Bus Manager) or EFII in general when they show >un-necessary SPOFs that will stop the engine. Ref EFII Dwg 9 rev >5/19 that you attached. How about a Z101 engine bus? It's already managed. >50A is more than an engine bus requires. I am planning on dual four >cylinder SDS EFI+I on O-360 and my calculations show: >ECU 0.13A Agreed >Coilpack 1.1A at cruise >Fuel pump 5.25A at 45 PSI (Walbro GSL393) >14.5 Ohm injectors 0.32A each at cruise (32% duty cycle, 10 GPH) >I plan to put both EFI+I systems (pri and bak) on one engine bus and >the current draw is less than 20A (15A with both pumps and coils >running for low altitude; 8.2A with one coil and one pump running in >current conservation mode). >I'm planning on an adaptation of Z-101 which is simpler than Z-14 >and IMO just as reliable. >It would be simpler and more reliable to have separate toggle >switches for the main and aux fuel pumps and eliminate the fuel >pressure switch. >The fuel pressure switch is called NO; I would think that means it >is open when there is no fuel pressure so the logic is backwards. >You mentioned dwg 1.04 but attached 1.00. Wire and fusing sizes depicted are not clear as to design goals. Diode -ored power sources should locate diodes at the load end of each feed. As shown, faults downstream of diodes would take out both feeders. Fusible links are not useful here . . . in fact, any fault that would open a fusible link would take out both fuses. The drawing is exceedingly 'busy'. A three source, dual feed engine bus can replace un-necessary 'redundancy' . . . offers opportunity for each load to enjoy its own protected feeder thus maximizing failure tolerance while reducing system costs, weight and parts count. 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