---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Wed 07/13/16: 6 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 07:14 AM - Question OV Crowbar connection in Z16 figure (zwakie) 2. 09:16 AM - Re: Question OV Crowbar connection in Z16 figure (Robert L. Nuckolls, III) 3. 05:04 PM - Optima Prius Battery For TIO-540 (William Hunter) 4. 05:09 PM - Lay Flat Battery Contactor and Starter Relay (William Hunter) 5. 06:25 PM - Re: Lay Flat Battery Contactor and Starter Relay (A R Goldman) 6. 08:50 PM - Re: Question OV Crowbar connection in Z16 figure (Robert L. Nuckolls, III) ________________________________ Message 1 _____________________________________ Time: 07:14:09 AM PST US Subject: AeroElectric-List: Question OV Crowbar connection in Z16 figure From: "zwakie" I am in the designing stage for a new electrical system for my Rotax 912S powered Europa and am using Z16 as the basis. By now I have a pretty thorough understanding of the philosophy of Z16, but one question keeps popping up in my mind: Why is the positive side of the crowbar OV module connected to the 'downstream side' of the master switch? In my reasoning I believe it to be more robust to connect the positive side of the OV module to the downstream side of the 5A C/B. This would take the master switch and the wire between C/B and master switch out as potential points of failure during an O/V situation: Master Bus -> Fuselink > 18AWG wire > to C/B Then run 2 circuits from this C/B: (1) --> to OV Module (2) --> 22AWG wire > to Master Switch I know this would be a small amount of additional protection for situation that is likely to be very rare, but it's a very minor and easy change to Z16 so why not make this minor change? So basically what I would like to know: is there any reason why I should not connect it like this? -------- Marcel Zwakenberg XS TG || 912ULS || PH-SBR Read this topic online here: http://forums.matronics.com/viewtopic.php?p=458125#458125 ________________________________ Message 2 _____________________________________ Time: 09:16:12 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Question OV Crowbar connection in Z16 figure At 09:10 AM 7/13/2016, you wrote: > >I am in the designing stage for a new electrical system for my Rotax >912S powered Europa and am using Z16 as the basis. By now I have a >pretty thorough understanding of the philosophy of Z16, but one >question keeps popping up in my mind: > >Why is the positive side of the crowbar OV module connected to the >'downstream side' of the master switch? > >In my reasoning I believe it to be more robust to connect the >positive side of the OV module to the downstream side of the 5A C/B. >This would take the master switch and the wire between C/B and >master switch out as potential points of failure during an O/V situation: You can do that . . . it makes no significant difference. Bob . . . ________________________________ Message 3 _____________________________________ Time: 05:04:24 PM PST US From: "William Hunter" Subject: AeroElectric-List: Optima Prius Battery For TIO-540 Greetings, I am building a Dual Battery/Dual Alternator electrical system for a single Engine Velocity. The engine is a TIO-540 (turbo) and I notate this because the engine only has 7.3 to one compression pistons so therefore the starter motor will not have to fight against the usual 8.3 to 1 compression. One battery will be mounted in the nose and one battery will be mounted under the back seat. Optima sells a 12V Prius battery that they advertise as "38 AH / CCA of 450 amps / MCA of 575 amps" and this battery is only 26 LBS. http://www.optimabatteries.com/en-us/shop/yellowtop/optima-batteries-ds46b24 r-yellowtop-prius-auxiliary-battery/ Concord has a "Platinum Series" replacement battery for a Aztec and this airplane has an IO-540 (with normal compression pistons) and the top of the line Concord battery advertises Rated Capacity C1 = 1 hr. rate in ampere hours 33.00 Cold Cranking Amps 440.0 and it is 33 pounds. Even though my airplane will have two batteries I still want to be able to start my 6 banger engine with a single battery. Does the collective wisdom on this forum believe that a singular Prius battery will be sufficient for the starting of my engine? .. THANKS!!! Bill Hunter ________________________________ Message 4 _____________________________________ Time: 05:09:40 PM PST US From: "William Hunter" Subject: AeroElectric-List: Lay Flat Battery Contactor and Starter Relay I vaguely remember one of Bob's majestic musings that articulately dispelled the long time myth mandating that battery contactors and starter relays must be installed vertically against a wall and not installed flat on a floorboard. My proposed installation of mounting them on a wall is not going to work and I want to mount them under the back seat against the floorboards. Can someone please confirm that my recollection described above is indeed accurate and I was not just dreaming Bob's majestic words?!?!? .. Cheers!!! Bill Hunter ________________________________ Message 5 _____________________________________ Time: 06:25:27 PM PST US From: A R Goldman Subject: Re: AeroElectric-List: Lay Flat Battery Contactor and Starter Relay Don't know about the general battery contractor, but I have heard that the s tarter solenoid should not be mounted upright since in the open position the disconnection is created by a spring and in a hard landing (which we never d o) momentum will cause the contactor to close momentarily and possibly do da mage to the starter ring on the flywheel or the gear on the starter motor. My starter contactor's mounting flange is such that it demands to be mounted in a horizontal orientation unless I Mage an angle bracket No worry about the general contactor as it will be closed (against the sprin g) when landing Rich Sent from my iPhone > On Jul 13, 2016, at 7:02 PM, William Hunter w rote: > > I vaguely remember one of Bob=99s majestic musings that articulately dispelled the long time myth mandating that battery contactors and starter r elays must be installed vertically against a wall and not installed flat on a floorboard. My proposed installation of mounting them on a wall is not goi ng to work and I want to mount them under the back seat against the floorboa rds. > > Can someone please confirm that my recollection described above is indeed a ccurate and I was not just dreaming Bob=99s majestic words?!?!? > > .. > > Cheers!!! > > Bill Hunter ________________________________ Message 6 _____________________________________ Time: 08:50:10 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Question OV Crowbar connection in Z16 figure At 09:10 AM 7/13/2016, you wrote: > >I am in the designing stage for a new electrical system for my Rotax >912S powered Europa and am using Z16 as the basis. By now I have a >pretty thorough understanding of the philosophy of Z16, but one >question keeps popping up in my mind: > >Why is the positive side of the crowbar OV module connected to the >'downstream side' of the master switch? > >In my reasoning I believe it to be more robust to connect the >positive side of the OV module to the downstream side of the 5A C/B. >This would take the master switch and the wire between C/B and >master switch out as potential points of failure during an O/V situation: You can do that . . . it makes no significant difference. 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