---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Wed 12/17/03: 32 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 12:21 AM - Re: Airspeed Indicator (mailbox bob at mail.flyboybob.com) 2. 04:14 AM - JPI interference... (Mitchell M. Berger) 3. 04:18 AM - Re: Airspeed Indicator (William) 4. 05:20 AM - airspeed indicator (Gary Casey) 5. 06:50 AM - Re: OV Protection Module (Rhett Westerman) 6. 07:11 AM - ECI OAT Reads High. (N27160@aol.com) 7. 07:12 AM - Re: Airspeed Indicator (Alex Peterson) 8. 07:27 AM - Re: airspeed indicator (Robert L. Nuckolls, III) 9. 08:19 AM - Re: ECI OAT Reads High. (Joel Harding) 10. 08:34 AM - Re: Airspeed Indicator (Jim Sower) 11. 08:37 AM - Re: Airspeed Indicator (Jim Sower) 12. 09:01 AM - Re: LED taillight fir the A555 whelen (Eric M. Jones) 13. 09:48 AM - My 100th anniversary Commemorative flight (royt.or@netzero.com) 14. 09:50 AM - MicroAir transponder wiriing harness problem (Rick Fogerson) 15. 10:22 AM - Re: Airspeed Indicator (George Braly) 16. 11:35 AM - Re: LED taillight for the A555 whelen (Eric M. Jones) 17. 12:18 PM - Re: MicroAir transponder wiriing harness (Robert L. Nuckolls, III) 18. 12:18 PM - Re: OV Protection Module (Robert L. Nuckolls, III) 19. 12:45 PM - MOV's/Transorbs? (Gary Graham) 20. 12:51 PM - Re: ECI OAT Reads High. (AI Nut) 21. 01:23 PM - Electrical Design Question (Brett Ferrell) 22. 02:18 PM - Re: Airspeed Indicator (Jim Sower) 23. 02:22 PM - Re: Electrical Design Question (Matt Prather) 24. 05:57 PM - Re: Airspeed Indicator (Pete & Farrell Rouse) 25. 06:38 PM - Re: MOV's/Transorbs? (Robert L. Nuckolls, III) 26. 06:43 PM - Re: Electrical Design Question (Robert L. Nuckolls, III) 27. 06:55 PM - Re: Airspeed Indicator (Kevin Horton) 28. 07:21 PM - Re: Electrical Design Question (Brett Ferrell) 29. 07:30 PM - Re: No Electric Starter/System Ques (Robert L. Nuckolls, III) 30. 08:51 PM - [ Jim Jewell ] : New Email List Photo Share Available! (Email List Photo Shares) 31. 09:27 PM - Re: Airspeed Indicator (David Carter) 32. 10:03 PM - Fat Feed Relay & Contactor (Don Boardman) ________________________________ Message 1 _____________________________________ Time: 12:21:18 AM PST US From: "mailbox bob at mail.flyboybob.com" Subject: RE: AeroElectric-List: Airspeed Indicator --> AeroElectric-List message posted by: "mailbox bob at mail.flyboybob.com" Jim Sower Wrote: I'm looking for a throwaway airspeed indicator. I'm trying to get my cooling as optimized as I can, and need some "acceptably reliable" data on the pressure drop from the plenum below the engine to the exit above the engine. Jim, How about a transfer valve of some type? You could switch your airspeed from pitot/static to cowl-plenum/cowl-exit. That way you could always test your cowl seals in the future by flipping the valve to the "Alternate pitot/static" position. Due to the heat in the engine the "Alternate pitot/static source would not be likely to ice up in the winter. You could mark the valve "normal pitot/static" and "heated pitot/static". Why do something that is temporary when cooling is something that often deteriorates over time. If you use a valve you can make sure that your improvements do not change over time. Regards, Bob Lee ______________________________ N52BL KR2 Suwanee, GA 30024 91% done only 51% to go! Phone/Fax: 770/844-7501 mailto:bob@flyboybob.com http://flyboybob.com ________________________________ Message 2 _____________________________________ Time: 04:14:57 AM PST US From: "Mitchell M. Berger" Subject: AeroElectric-List: JPI interference... HTML_FONTCOLOR_RED@matronics.com, HTML_FONTCOLOR_UNSAFE@matronics.com --> AeroElectric-List message posted by: "Mitchell M. Berger" I recently installed a JPI 700 EDM with EGT CHT OIL TEMP OAT and Voltage. It works fine; however when I printed out data downloaded from the data port and displayed it on their EZPlot software there appeared to be some interference with the EGT readings, ie the graph lines were 'jagged' indicating some kind of buzzing. The CHT readouts were normally displayed. I called JPI and sent them the data. They said it probably isn't a poor ground because the CHT's would have been effected also. Has anybody experienced this and/or have any suggestions? The wires are routed separately from the ignition leads and are not bundled with them. If anyone wants to check the display data let me know and I'll email it. You'll need the EZPlot software though, I believe. Best, Mitch Berger Mitchell M. Berger, Esq Berger Law Offices, LLC 80 Phoenix Avenue Suite 201 Waterbury, CT 06702 203 597-9877 203 206-0383 (cell) 203 756-4789 (fax) 509 351-7900 (fax computer) mberger@snet.net ________________________________ Message 3 _____________________________________ Time: 04:18:15 AM PST US From: "William" Subject: Re: AeroElectric-List: Airspeed Indicator --> AeroElectric-List message posted by: "William" Why not use a water manometer? Bill Schertz KIS Cruiser # 4045 ----- Original Message ----- From: "Jim Sower" Subject: AeroElectric-List: Airspeed Indicator > --> AeroElectric-List message posted by: Jim Sower > > I'm looking for a throwaway airspeed indicator. I'm trying to get my cooling as optimized as > I can, and need some "acceptably reliable" data on the pressure drop from the plenum below > the engine to the exit above the engine. It doesn't have to be all that accurate, but since > I'll hardly be using it after this problem is solved, it has to be VERY affordable. > Anyone have an old beat up no account ASI? .... Jim S. > -- > Jim Sower > Crossville, TN; Chapter 5 > Long-EZ N83RT, Velocity N4095T > > ________________________________ Message 4 _____________________________________ Time: 05:20:52 AM PST US From: "Gary Casey" Subject: AeroElectric-List: airspeed indicator --> AeroElectric-List message posted by: "Gary Casey" <> I just bought one off E-bay for $7 - $1 for the indicator and $6 for shipping. It took 3 or 4 tries as some would get priced up during the last few seconds I just kept putting in bids of about $15 until there was one that everyone ignored. Don't know if it is accurate, but the needle moves when I blow in it. I'm hoping it's close enough and I intend to do the same thing you have planned - I hope you share the results of the testing. Gary Casey ________________________________ Message 5 _____________________________________ Time: 06:50:05 AM PST US From: "Rhett Westerman" Subject: RE: AeroElectric-List: OV Protection Module --> AeroElectric-List message posted by: "Rhett Westerman" Bob, Thanks for the OV module. I received the new one, put it in and same thing happened - blew the fuse. I think I narrowed it down to when I would transmit on the radio. I then replaced the voltage regulator and it has now worked for about 6 hours, so I feel it is fixed. thanks, Rhett -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com]On Behalf Of Robert L. Nuckolls, III Subject: Re: AeroElectric-List: OV Protection Module --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" At 03:36 PM 12/7/2003 -0600, you wrote: >--> AeroElectric-List message posted by: "Rhett Westerman" > > >Bob, > > I have a Glastar and use your OV Module. The plane has been flying since 98 >and has approx 800 hours on it. Last year the OV Module went out and it >appears to have gone out again. About 150 hours on the new one you sent me. > > It keeps tripping and blowing the fuse. This occurred three times today. I >have the Vision system which allows me to see the high and low voltages for >the flight. Each time the high voltage was 14.2 volts. I am unsure of the >sampling rate of the vision, but if there are voltage spikes they are faster >then the vision can catch and it had three tries. > > From what I have seen, this seems very unusual......any ideas....or am I >just getting bad modules? Refresh my memory. When it "went out" the first time, did you send it to me for modification or did I send you a new one. When you say "fuse" do you mean circuit breaker? The Vision Micro will not "see" the kind of transient usually common to nuisance tipping an crowbar ov module. If the first one was "bad" and sent back to me for mod, I would have brought it up to date with current production. What equipment was ON while the OV module was tripping? Was this configuration much different than previous flight activity? Would you be willing to try an experiment to see if we can isolate any potential antagonist systems? Bob . . . ________________________________ Message 6 _____________________________________ Time: 07:11:27 AM PST US From: N27160@aol.com Subject: AeroElectric-List: ECI OAT Reads High. --> AeroElectric-List message posted by: N27160@aol.com I keep having an error in my Electronics International OAT gauge, reading high in flight. On the ground, engine off, it reads fine. The probe sticks through the fusealge with the interior side being inside the cabin behind the firewall. Its positioned on the side of the fuselage, not near exhaust etc. Checked all the connections. Any ideas? ________________________________ Message 7 _____________________________________ Time: 07:12:02 AM PST US From: "Alex Peterson" Subject: RE: AeroElectric-List: Airspeed Indicator --> AeroElectric-List message posted by: "Alex Peterson" > I'm looking for a throwaway airspeed indicator. I'm trying > to get my cooling as optimized as I can, and need some > "acceptably reliable" data on the pressure drop from the > plenum below the engine to the exit above the engine. It > doesn't have to be all that accurate, but since I'll hardly > be using it after this problem is solved, it has to be VERY > affordable. Anyone have an old beat up no account ASI? .... Jim S. > -- > Jim Sower > Crossville, TN; Chapter 5 > Long-EZ N83RT, Velocity N4095T Jim, I did precisely what you are contemplating with my RV6A, only I used a simple manometer that I fashioned with some pvc tubing. I put valves in the lines so that I could measure pressure (compared to cabin static) both above and below the engine. Alternatively, I could also move the little valves until I simply got pressure differential across the engine. I don't have any pictures of this setup, but the interesting thing is how little I was able to effect the pressures with the various mods I did. Some pictures of these mods are available at http://www.usfamily.net/web/alexpeterson/coolingmods.htm, although they obviously don't apply to a Long-EZ. This was discussed on the RV list about a year ago, if you search for my name and cooling, you might get a few hits. Alex Peterson Maple Grove, MN RV6-A N66AP 424 hours www.usfamily.net/web/alexpeterson ________________________________ Message 8 _____________________________________ Time: 07:27:41 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: airspeed indicator --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" At 05:19 AM 12/17/2003 -0800, you wrote: >--> AeroElectric-List message posted by: "Gary Casey" > ><cooling as >optimized as >I can, and need some "acceptably reliable" data on the pressure drop from >the plenum >below >the engine to the exit above the engine. It doesn't have to be all that >accurate, >but since >I'll hardly be using it after this problem is solved, it has to be VERY >affordable. >Anyone have an old beat up no account ASI? .... Jim S.>> > >I just bought one off E-bay for $7 - $1 for the indicator and $6 for >shipping. It took 3 or 4 tries as some would get priced up during the last >few seconds I just kept putting in bids of about $15 until there was one >that everyone ignored. Don't know if it is accurate, but the needle moves >when I blow in it. I'm hoping it's close enough and I intend to do the same >thing you have planned - I hope you share the results of the testing. > >Gary Casey How about a U-tube, water manometer? You can fit it with a pair of hoses that can be terminated in various places under the cowl to measure very small pressure differentials. In fact, you can make the manometer and sense tubes all from the same length of material. I've fabricated these from aquarium air line with the "u" wrapped around the end of a yardstick - or piece of yardstick when you need a short one. Put enough water in colored with food coloring to give you two columns about equal to max anticipated pressure differential (This will give you 2x headroom . . . while one column goes up 1", the other goes down 1" making pressure delta 2"). Install with clamp on one of the sense tubes and leave clamp closed until you're ready to make a measurement. Open slowly to make sure you've not tapped into a very high delta-p situation that's going to blow the water clear out of the system. Keep clamp closed except when taking a reading. This $5 instrument is very sensitive and will get you good data wherein "calibration" is not an issue. Bob . . . ________________________________ Message 9 _____________________________________ Time: 08:19:52 AM PST US Subject: Re: AeroElectric-List: ECI OAT Reads High. From: Joel Harding --> AeroElectric-List message posted by: Joel Harding Check the intersection of the cowl and side skin ahead of the probe. There's a good chance warm air from under the cowl is leaking out and impinging on your probe. Joel Harding On Wednesday, Dec 17, 2003, at 08:11 America/Denver, N27160@aol.com wrote: > --> AeroElectric-List message posted by: N27160@aol.com > > I keep having an error in my Electronics International OAT gauge, > reading > high in flight. On the ground, engine off, it reads fine. > The probe sticks through the fusealge with the interior side being > inside the > cabin behind the firewall. Its positioned on the side of the > fuselage, not > near exhaust etc. Checked all the connections. Any ideas? > > > _- > ======================================================================= > _-> _- > ======================================================================= > _- > ======================================================================= > _- > ======================================================================= > _- > ======================================================================= > > > > ________________________________ Message 10 ____________________________________ Time: 08:34:53 AM PST US From: Jim Sower Subject: Re: AeroElectric-List: Airspeed Indicator --> AeroElectric-List message posted by: Jim Sower I've been there. Turned out messy and awkward for me. ASI is more accurate (better granularity). I think I've got a line on a real cheap one now. Jim S. Kingsley Hurst wrote: > Jim, > > How would a simple manometer "U tube" made of plastic tubing be? Very > cheap! I don't have it to hand at this moment, but a few months ago > (could even be up to 12 mths) there was discussion on this list of how > to calibrate same for the checking of ASI's. > > Just found the following reference on the web which may be of some > assistance. > > http://www.efunda.com/formulae/fluids/manometer.cfm#calc > > Regards > Kingsley Hurst > Europa Mono Classic 281 > in Oz > About to install third and final window.-- Jim Sower Crossville, TN; Chapter 5 Long-EZ N83RT, Velocity N4095T ________________________________ Message 11 ____________________________________ Time: 08:37:17 AM PST US From: Jim Sower Subject: Re: AeroElectric-List: Airspeed Indicator --> AeroElectric-List message posted by: Jim Sower I think a $10 ASI is probably a better idea than compromising my pitot static system. I would prefer even a manometer to screwing with the pitot static system. > How about a transfer valve of some type? You could switch your airspeed > from pitot/static to cowl-plenum/cowl-exit. That way you could always test > your cowl seals in the future by flipping the valve to the "Alternate > pitot/static" position. Due to the heat in the engine the "Alternate > pitot/static source would not be likely to ice up in the winter. You could > mark the valve "normal pitot/static" and "heated pitot/static". Why do > something that is temporary when cooling is something that often > deteriorates over time. If you use a valve you can make sure that your > improvements do not change over time. > > Regards, > > Bob Lee > ______________________________ > N52BL KR2 Suwanee, GA 30024 > 91% done only 51% to go! > Phone/Fax: 770/844-7501 > mailto:bob@flyboybob.com > http://flyboybob.com > -- Jim Sower Crossville, TN; Chapter 5 Long-EZ N83RT, Velocity N4095T ________________________________ Message 12 ____________________________________ Time: 09:01:50 AM PST US From: "Eric M. Jones" "Robert L. Nuckolls, III" , "Lancair Mailing List" , "Ralph E. Capen" , "Bob G" , "Timothy Ong" , "Jeffrey Peterson" , , "Carl Cadwell" , "Denny" , "craig blitzer" , "Ron Laughlin" , , "Steve Reames" , "Paul McAllister" , , "Bruce Gray" Subject: AeroElectric-List: Re: LED taillight fir the A555 whelen --> AeroElectric-List message posted by: "Eric M. Jones" You might be interested in my LED tail light available in January. See attached. Regards, Eric M. Jones www.PerihelionDesign.com 113 Brentwood Drive Southbridge MA 01550-2705 Phone (508) 764-2072 Email: emjones@charter.net ________________________________ Message 13 ____________________________________ Time: 09:48:20 AM PST US Subject: AeroElectric-List: My 100th anniversary Commemorative flight From: royt.or@netzero.com --> AeroElectric-List message posted by: royt.or@netzero.com Details of my flight to celebrate the 100th anniversary of powered flight. (Cross posted to Zenith list and Aeroelctric-list) I did a takeoff in my centennial homebuilt, CH601HDS, about 7:20 PST this morning and planned to stay in the pattern for 20 or 30 minutes to celebrate the 100th anniversary of power flight and the efforts of the original homebuilders. During my first trip around the pattern, the field was declared IFR, and I was given special VFR permission to land. (Just one end of the field was fogged in, I could see fine.) SO, after landing I asked permission to do a high speed taxi on the inactive runway. At 7:35PST (10:35 EST) I accelerated to near takeoff speed, floated the Zodiac a few feet off the ground for 10 to 15 seconds (during which time the tower reminded me the field was IFR and I WAS NOT to be airborne) and settled back to the runway. Not what I planned, but as close to a perfect match of the flight 100 years ago as I could possibly imagine. It was great. Regards, Roy ________________________________ Message 14 ____________________________________ Time: 09:50:38 AM PST US From: "Rick Fogerson" Subject: AeroElectric-List: MicroAir transponder wiriing harness problem --> AeroElectric-List message posted by: "Rick Fogerson" Hi Bob, I ordered and received a wiring harness from you a few months back. Just now getting around to installing the Micro Air xpdr and Rocky Mtn Micro Encoder. Problems are as follows: 1) The 15 pin connector on the harness and the back of the Micro Encoder are both female. Besides not very exciting to watch there was no consumation of this type of union. 2) It appears that the pin locations are also incompatible. Really a troubled relationship. If you need them, I will send the pin callouts for a Micro Encoder. What next? Rick Fogerson RV3 wiring Boise, ID ________________________________ Message 15 ____________________________________ Time: 10:22:48 AM PST US From: George Braly Subject: RE: AeroElectric-List: Airspeed Indicator --> AeroElectric-List message posted by: George Braly Jim, The ASI is OK. The water works but it is a bit messy and difficult. You should not expect to see more than about 3" to 8" of water column difference. An ASI reads about 200 knots at 2 PSI differential. Note the difference in units!!! HOWEVER... you will not get meaningfully useful readings unless you install piccolo tubes on both the input and the reference (static) side of the tubing that you run to the ASI. There are some cheap low pressure differential pressure transducers that will work nicely and are calibrated in the 0-10 or 0-15" H2O span. You can read the output with a volt meter. Regards, George -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com]On Behalf Of Jim Sower Subject: Re: AeroElectric-List: Airspeed Indicator --> AeroElectric-List message posted by: Jim Sower I've been there. Turned out messy and awkward for me. ASI is more accurate (better granularity). I think I've got a line on a real cheap one now. Jim S. Kingsley Hurst wrote: > Jim, > > How would a simple manometer "U tube" made of plastic tubing be? Very > cheap! I don't have it to hand at this moment, but a few months ago > (could even be up to 12 mths) there was discussion on this list of how > to calibrate same for the checking of ASI's. > > Just found the following reference on the web which may be of some > assistance. > > http://www.efunda.com/formulae/fluids/manometer.cfm#calc > > Regards > Kingsley Hurst > Europa Mono Classic 281 > in Oz > About to install third and final window.-- Jim Sower Crossville, TN; Chapter 5 Long-EZ N83RT, Velocity N4095T --- Incoming mail is certified Virus Free. --- ________________________________ Message 16 ____________________________________ Time: 11:35:56 AM PST US From: "Eric M. Jones" Subject: AeroElectric-List: Re: LED taillight for the A555 whelen --> AeroElectric-List message posted by: "Eric M. Jones" Yeah yeah yeah sorry....okay. Try www.periheliondesign.com/led555taillightflyer.pdf Eric ________________________________ Message 17 ____________________________________ Time: 12:18:05 PM PST US From: "Robert L. Nuckolls, III" problem Subject: Re: AeroElectric-List: MicroAir transponder wiriing harness problem --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" problem At 10:53 AM 12/17/2003 -0700, you wrote: >--> AeroElectric-List message posted by: "Rick Fogerson" > >Hi Bob, >I ordered and received a wiring harness from you a few months back. Just >now getting around to installing the Micro Air xpdr and Rocky Mtn Micro >Encoder. Problems are as follows: > >1) The 15 pin connector on the harness and the back of the Micro Encoder >are both female. Besides not very exciting to watch there was no >consumation of this type of union. > >2) It appears that the pin locations are also incompatible. Really a >troubled relationship. If you need them, I will send the pin callouts for >a Micro Encoder. Hmmm . . . did we talk about this when you ordered your harness? I've never had a pinout diagram for Rocky Mountain's products in house . . . so if we offered you a plug-n-play harness at the time, I had to have been out in left field somewhere. If you have pinout data for the encoder and want to sent your harness back, I'll install the proper plug. Bob . . . ________________________________ Message 18 ____________________________________ Time: 12:18:48 PM PST US From: "Robert L. Nuckolls, III" Subject: RE: AeroElectric-List: OV Protection Module --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" At 08:50 AM 12/17/2003 -0600, you wrote: >--> AeroElectric-List message posted by: "Rhett Westerman" > > >Bob, > > Thanks for the OV module. I received the new one, put it in and same thing >happened - blew the fuse. I think I narrowed it down to when I would >transmit on the radio. I then replaced the voltage regulator and it has now >worked for about 6 hours, so I feel it is fixed. Pleased to hear that. As we discussed in our telephone conversation this morning, I'd still like to get your old OV module back. You can leave the new one in place with my compliments. Bob . . . ________________________________ Message 19 ____________________________________ Time: 12:45:49 PM PST US Subject: AeroElectric-List: MOV's/Transorbs? From: Gary Graham --> AeroElectric-List message posted by: Gary Graham Bob, In the mid 90's I wired my airplane (RV) master/starter contactors with those MOV's you recommended then. For many years since then you have called out the spike catcher diodes. Do I need to change for better physics? Do the MOV's have a useful life caused by the inductive spikes that they pass? What would you do? Gary ________________________________ Message 20 ____________________________________ Time: 12:51:24 PM PST US From: "AI Nut" Subject: Re: AeroElectric-List: ECI OAT Reads High. --> AeroElectric-List message posted by: "AI Nut" Maybe it's in an engine heat stream? AI Nut ----- Original Message ----- From: Subject: AeroElectric-List: ECI OAT Reads High. > --> AeroElectric-List message posted by: N27160@aol.com > > I keep having an error in my Electronics International OAT gauge, reading > high in flight. On the ground, engine off, it reads fine. > The probe sticks through the fusealge with the interior side being inside the > cabin behind the firewall. Its positioned on the side of the fuselage, not > near exhaust etc. Checked all the connections. Any ideas? > > > _- ________________________________ Message 21 ____________________________________ Time: 01:23:44 PM PST US From: "Brett Ferrell" Subject: AeroElectric-List: Electrical Design Question --> AeroElectric-List message posted by: "Brett Ferrell" Here's one for you electrical design/engineer types, I have a essential bus in my all electric plane system design, with the back feed diode that's rated at (I believe) 25 amps from BandC. My normal ESS running load will be just over 8 amps, the published max loads for these items is just over 18, but because the manufacturers recommend much larger breakers for thier equipment (like the blue mountain EFIS), the breaker protected max load for the line will be almost 40A (15 for pitot, 10 for the EFIS, a comm, a nav, xponder, intercomm, and the left electronic ignition). I feel like I should parallel two of these diodes so I don't risk burning one up, but it also feels like overkill. What's the best practice/convention on something like this? Brett ________________________________ Message 22 ____________________________________ Time: 02:18:46 PM PST US From: Jim Sower Subject: Re: AeroElectric-List: Airspeed Indicator --> AeroElectric-List message posted by: Jim Sower I'm told that if I put the pitot port to the plenum and the static port above the engine I can expect about 120 KIAS delta which is rumored to be the equivalent of about 4" H2O. I'll do the math before I do any testing to determine what to look for by way of IAS. First, I'll need to look up SL, std day rho .... Jim S. George Braly wrote: > --> AeroElectric-List message posted by: George Braly > > Jim, > > The ASI is OK. The water works but it is a bit messy and difficult. > > You should not expect to see more than about 3" to 8" of water column > difference. > > An ASI reads about 200 knots at 2 PSI differential. Note the difference in > units!!! > > HOWEVER... you will not get meaningfully useful readings unless you install > piccolo tubes on both the input and the reference (static) side of the > tubing that you run to the ASI. > > There are some cheap low pressure differential pressure transducers that > will work nicely and are calibrated in the 0-10 or 0-15" H2O span. > > You can read the output with a volt meter. > > Regards, George > > -----Original Message----- > From: owner-aeroelectric-list-server@matronics.com > [mailto:owner-aeroelectric-list-server@matronics.com]On Behalf Of Jim > Sower > To: aeroelectric-list@matronics.com > Subject: Re: AeroElectric-List: Airspeed Indicator > > --> AeroElectric-List message posted by: Jim Sower > > > I've been there. Turned out messy and awkward for me. ASI is more accurate > (better > granularity). I think I've got a line on a real cheap one now. > Jim S. > > Kingsley Hurst wrote: > > > Jim, > > > > How would a simple manometer "U tube" made of plastic tubing be? Very > > cheap! I don't have it to hand at this moment, but a few months ago > > (could even be up to 12 mths) there was discussion on this list of how > > to calibrate same for the checking of ASI's. > > > > Just found the following reference on the web which may be of some > > assistance. > > > > http://www.efunda.com/formulae/fluids/manometer.cfm#calc > > > > Regards > > Kingsley Hurst > > Europa Mono Classic 281 > > in Oz > > About to install third and final window.-- > > Jim Sower > Crossville, TN; Chapter 5 > Long-EZ N83RT, Velocity N4095T > > --- > Incoming mail is certified Virus Free. > > --- > -- Jim Sower Crossville, TN; Chapter 5 Long-EZ N83RT, Velocity N4095T ________________________________ Message 23 ____________________________________ Time: 02:22:52 PM PST US Subject: Re: AeroElectric-List: Electrical Design Question From: "Matt Prather" --> AeroElectric-List message posted by: "Matt Prather" I have a couple of thoughts relating.... Vendors specify oversized circuit protection because it's easy, and reduces the chances of nuisance tripping. Some components may demand significant inrush turn on current. The worst case current draw through the diode could be found if all your endurance bus components were turned on at the same instant.. Is this likely to happen? Further, the inrush currents are transient, not continuous. Diodes will hanle momentary over spec current (within reason). The limits are largely thermal issues. It takes some amount of time to build up heat. Finally, adding diodes in parallel may not improve the thermal side of things, unless the components are matched, ideally from the same production lot. The current - voltage relationship for two diodes, especially unmatched, is never exactly the same. What ends up happening is that the turn-on voltage for one diode is always a little bit less than the other and so one diode ends up carrying most of the load. If you need more continuous current capability, you need to get a diode that is spec'ed for more load. Regards, Matt Prather VEZE N34RD > --> AeroElectric-List message posted by: "Brett Ferrell" > > > Here's one for you electrical design/engineer types, > > I have a essential bus in my all electric plane system design, with the > back feed diode that's rated at (I believe) 25 amps from BandC. My > normal ESS running load will be just over 8 amps, the published max > loads for these items is just over 18, but because the manufacturers > recommend much larger breakers for thier equipment (like the blue > mountain EFIS), the breaker protected max load for the line will be > almost 40A (15 for pitot, 10 for the EFIS, a comm, a nav, xponder, > intercomm, and the left electronic ignition). I feel like I should > parallel two of these diodes so I don't risk burning one up, but it also > feels like overkill. What's the best practice/convention on something > like this? > > Brett > > ________________________________ Message 24 ____________________________________ Time: 05:57:36 PM PST US From: "Pete & Farrell Rouse" Subject: Re: AeroElectric-List: Airspeed Indicator --> AeroElectric-List message posted by: "Pete & Farrell Rouse" Jim, You will need to put the Pitot (Total Pressure) tap in the upper plenum, on the top side of the baffling, and the static pressure tap below the baffling. The static pressure difference between above the baffling and below is what causes the cooling air to flow, thus the pressure is higher on top of the baffling. This is true unless you have updraft cooling like Peter Garrison's Melmoth. The easy way to remember is: Inlet = High Pressure Outlet = Low Pressure To figure out the density of the air, use the following formula: rho = Pamb(psia)*144/(53.34*(Tamb(F)+459.67) On a 59deg F day at sea level: rho = 14.696*144/(53.34*(59+459.67)) rho = 0.07649lbm/ft 3 I have created a spreadsheet to equate indicated airspeed to inches of water pressure differential. I will be happy to send it to you, if you want. Pete Rouse ----- Original Message ----- From: "Jim Sower" Subject: Re: AeroElectric-List: Airspeed Indicator > --> AeroElectric-List message posted by: Jim Sower > > I'm told that if I put the pitot port to the plenum and the static port above > the engine I can expect about 120 KIAS delta which is rumored to be the > equivalent of about 4" H2O. I'll do the math before I do any testing to > determine what to look for by way of IAS. > First, I'll need to look up SL, std day rho .... Jim S. > > George Braly wrote: > > > --> AeroElectric-List message posted by: George Braly > > > > Jim, > > > > The ASI is OK. The water works but it is a bit messy and difficult. > > > > You should not expect to see more than about 3" to 8" of water column > > difference. > > > > An ASI reads about 200 knots at 2 PSI differential. Note the difference in > > units!!! > > > > HOWEVER... you will not get meaningfully useful readings unless you install > > piccolo tubes on both the input and the reference (static) side of the > > tubing that you run to the ASI. > > > > There are some cheap low pressure differential pressure transducers that > > will work nicely and are calibrated in the 0-10 or 0-15" H2O span. > > > > You can read the output with a volt meter. > > > > Regards, George > > > > -----Original Message----- > > From: owner-aeroelectric-list-server@matronics.com > > [mailto:owner-aeroelectric-list-server@matronics.com]On Behalf Of Jim > > Sower > > To: aeroelectric-list@matronics.com > > Subject: Re: AeroElectric-List: Airspeed Indicator > > > > --> AeroElectric-List message posted by: Jim Sower > > > > > > I've been there. Turned out messy and awkward for me. ASI is more accurate > > (better > > granularity). I think I've got a line on a real cheap one now. > > Jim S. > > > > Kingsley Hurst wrote: > > > > > Jim, > > > > > > How would a simple manometer "U tube" made of plastic tubing be? Very > > > cheap! I don't have it to hand at this moment, but a few months ago > > > (could even be up to 12 mths) there was discussion on this list of how > > > to calibrate same for the checking of ASI's. > > > > > > Just found the following reference on the web which may be of some > > > assistance. > > > > > > http://www.efunda.com/formulae/fluids/manometer.cfm#calc > > > > > > Regards > > > Kingsley Hurst > > > Europa Mono Classic 281 > > > in Oz > > > About to install third and final window.-- > > > > Jim Sower > > Crossville, TN; Chapter 5 > > Long-EZ N83RT, Velocity N4095T > > > > --- > > Incoming mail is certified Virus Free. > > > > --- > > > > -- > Jim Sower > Crossville, TN; Chapter 5 > Long-EZ N83RT, Velocity N4095T > > ________________________________ Message 25 ____________________________________ Time: 06:38:13 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: MOV's/Transorbs? --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" At 12:45 PM 12/17/2003 -0800, you wrote: >--> AeroElectric-List message posted by: Gary Graham > >Bob, In the mid 90's I wired my airplane (RV) master/starter contactors >with those MOV's you recommended then. For many years since then you have >called out the spike catcher diodes. Do I need to change for better >physics? Do the MOV's have a useful life caused by the inductive spikes >that they pass? What would you do? The MOVs had a certain allure to them at the time . . . they are bi-directional devices and the installer didn't have to worry about polarity. Diodes on the other hand are much easier to find (low voltage MOVs are not commonly stocked except by large suppliers like Allied and Digikey) and do a better job of clamping off the inductive spike. I'm considering expanding the article on spike catcher diodes to illustrate the effects and "benefits" of MOVs and didoes + zeners (recommended by some relay manufacturers). I think I'd switch to diodes. Also, if you've got an MOV across the starter switch (as shown on some earlier diagrams) you can leave it there and simply add the diode across the starter contactor coil. Bob . . . ________________________________ Message 26 ____________________________________ Time: 06:43:58 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Electrical Design Question --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" At 04:23 PM 12/17/2003 -0500, you wrote: >--> AeroElectric-List message posted by: "Brett Ferrell" > > >Here's one for you electrical design/engineer types, > >I have a essential bus in my all electric plane system design, with the >back feed diode that's rated at (I believe) 25 amps from BandC. IF installed on adequate heat sink . . . >My normal ESS running load will be just over 8 amps, the published max >loads for these items is just over 18, but because the manufacturers >recommend much larger breakers for thier equipment (like the blue mountain >EFIS), the breaker protected max load for the line will be almost 40A (15 >for pitot, 10 for the EFIS, a comm, a nav, xponder, intercomm, and the >left electronic ignition). I feel like I should parallel two of these >diodes so I don't risk burning one up, but it also feels like >overkill. What's the best practice/convention on something like this? Are you using breakers or fuses? A fault downstream on a fuse will not hurt the diode (in spite of the fact that 300 or more amps will flow for milliseconds). I wouldn't worry about transient loads. For all those equipment items . . . just mount your diode assembly on a metal surface. Paralleling diodes is a mixed bag . . . they don't share loads well. I'd move the electronic ignition to the battery bus. Also, pitot heat doesn't go on an endurance bus. If you plan to spend long periods of time in clouds, you need two alternators. Bob . . . ________________________________ Message 27 ____________________________________ Time: 06:55:28 PM PST US From: Kevin Horton Subject: Re: AeroElectric-List: Airspeed Indicator --> AeroElectric-List message posted by: Kevin Horton 120 KIAS = 9.5" H2O I've got an Excel spreadsheet that converts between ASI and manometer readings: http://members.rogers.com/khorton/rvlinks/asi.zip Kevin Horton >--> AeroElectric-List message posted by: Jim Sower > >I'm told that if I put the pitot port to the plenum and the static port above >the engine I can expect about 120 KIAS delta which is rumored to be the >equivalent of about 4" H2O. I'll do the math before I do any testing to >determine what to look for by way of IAS. >First, I'll need to look up SL, std day rho .... Jim S. > >George Braly wrote: > >> --> AeroElectric-List message posted by: George Braly >> >> Jim, >> >> The ASI is OK. The water works but it is a bit messy and difficult. >> >> You should not expect to see more than about 3" to 8" of water column >> difference. >> >> An ASI reads about 200 knots at 2 PSI differential. Note the difference in >> units!!! >> >> HOWEVER... you will not get meaningfully useful readings unless you install >> piccolo tubes on both the input and the reference (static) side of the >> tubing that you run to the ASI. >> >> There are some cheap low pressure differential pressure transducers that >> will work nicely and are calibrated in the 0-10 or 0-15" H2O span. >> >> You can read the output with a volt meter. >> >> Regards, George >> >> -----Original Message----- >> From: owner-aeroelectric-list-server@matronics.com >> [mailto:owner-aeroelectric-list-server@matronics.com]On Behalf Of Jim >> Sower >> To: aeroelectric-list@matronics.com >> Subject: Re: AeroElectric-List: Airspeed Indicator >> >> --> AeroElectric-List message posted by: Jim Sower >> >> >> I've been there. Turned out messy and awkward for me. ASI is more accurate >> (better >> granularity). I think I've got a line on a real cheap one now. >> Jim S. >> >> Kingsley Hurst wrote: >> >> > Jim, >> > >> > How would a simple manometer "U tube" made of plastic tubing be? Very >> > cheap! I don't have it to hand at this moment, but a few months ago >> > (could even be up to 12 mths) there was discussion on this list of how >> > to calibrate same for the checking of ASI's. >> > >> > Just found the following reference on the web which may be of some >> > assistance. >> > >> > http://www.efunda.com/formulae/fluids/manometer.cfm#calc >> > >> > Regards >> > Kingsley Hurst >> > Europa Mono Classic 281 >> > in Oz > > > About to install third and final window.-- > > ________________________________ Message 28 ____________________________________ Time: 07:21:15 PM PST US From: "Brett Ferrell" Subject: Re: AeroElectric-List: Electrical Design Question --> AeroElectric-List message posted by: "Brett Ferrell" Thanks Bob, I'm installing 2 B&C alternators since I've got electronic ignition and all electric instruments, and have the essential bus in case I need to shutdown both, really. Kind of belt, suspenders and bib-overalls I guess, but I figured why not?.... Brett ----- Original Message ----- From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Electrical Design Question > --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" > > At 04:23 PM 12/17/2003 -0500, you wrote: > >--> AeroElectric-List message posted by: "Brett Ferrell" > > > > > >Here's one for you electrical design/engineer types, > > > >I have a essential bus in my all electric plane system design, with the > >back feed diode that's rated at (I believe) 25 amps from BandC. > > IF installed on adequate heat sink . . . > > >My normal ESS running load will be just over 8 amps, the published max > >loads for these items is just over 18, but because the manufacturers > >recommend much larger breakers for thier equipment (like the blue mountain > >EFIS), the breaker protected max load for the line will be almost 40A (15 > >for pitot, 10 for the EFIS, a comm, a nav, xponder, intercomm, and the > >left electronic ignition). I feel like I should parallel two of these > >diodes so I don't risk burning one up, but it also feels like > >overkill. What's the best practice/convention on something like this? > > Are you using breakers or fuses? A fault downstream on a fuse > will not hurt the diode (in spite of the fact that 300 or more > amps will flow for milliseconds). I wouldn't worry about transient > loads. For all those equipment items . . . just mount your diode > assembly on a metal surface. > > Paralleling diodes is a mixed bag . . . they don't share loads > well. I'd move the electronic ignition to the battery bus. > Also, pitot heat doesn't go on an endurance bus. If you > plan to spend long periods of time in clouds, you need two > alternators. > > Bob . . . > > ________________________________ Message 29 ____________________________________ Time: 07:30:10 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: No Electric Starter/System Ques --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" At 12:44 AM 12/17/2003 -0500, you wrote: >--> AeroElectric-List message posted by: Don Boardman > >Hi Bob and All. > >I have been pushing these questions around in my head making myself crazy. I >have read the Connection at least once (sections several times). I have been >into the archives. Just for the record, there are 474 postings containing >the words "Battery Bus". I still have questions. >SO I guess it's time to get clarification. I will try and organize it so >that answers can be inserted into the text. > >BACKGROUND >Our Moose with the M-14 radial engine uses an air start system and therefore >has no electric starter and no starter contactor. We are setting up the all >electric airplane on a budget using Z-13 as our reference. Z-13 accounts for >the use of a starter, part of my problem. We are using a Skytronics 50 amp >main alternator with their new voltage regulator which incorporates a >voltage protector. A SD-8 is our aux alternator. > >BATTERY >We are trying to decide on amp hour rating. In the RG Odessey line we see >12 ah PC545 @ 12 Lbs. 16 ah PC625 @ 13 Lbs. and the 16 ah PC680 @ 15 Lbs. > >*Without the need for electric start and having two alternators are we >foolish to > go larger than 12 ah.? I'd go with the cost-of-ownership decision. There are 17 a.h. batteries in the 3 x 7 x 7 form factor available for VERY reasonable cost due to huge-volume popularity of this particular battery. Unless you're really weight conscious, I'd go for the Panasonic 17 a.h. batteries that sell for as little as $40 each. With two alternators, you could probably consider swapping the battery out every two or three years. >HEAVY WIRES >The battery will be located under the co-pilots seat along with the battery >contactor. >I had anticipated using #4 wire to run my battery ground to the firewall and >to run from the battery contactor to the main bus. The aircraft wire I >purchased is pretty stiff (should have gotten welding cable) The 50 amp >alternator feed on the Skytronics installation schematic shows #6 if bundled >and #8 if in free air. I was planning on the purchase of #6 welding cable. >(and using an anl-60 already purchased) >? Do I need #4 wire from the battery given no starting circuit ? Would the >#6 FLEXIBLE welding > cable do the job? #8 ? Probably can't get #6 welding cable. That's pretty light for welding currents . . . #4 is easy to get, reasonably light and VERY easy to work with. How about #4 welding cable throughout? >HEAVY WIRE FEEDS, BATTERY AND CONTACTOR >#4 or as determined above. > >1. The battery negative cable goes directly to the firewall G2. > >2. The battery positive cable goes a short distance to the nearby >contactor's bat terminal. > >3. The output cable of the battery contactor goes to the Main Bus Fuse Block >located up under the > instrument panel. > ? Is it correct that this cable is to be placed out of harms way and is > not protected with i.e. large fuse or anl? Yes . . . > ?Is there any problem with this cable running to the Main Bus past the back >of the radio stack? Probably not . . . >MAIN ALTERNATOR OUTPUT > >1. ? Without a starter contactor will the output of the main 50 amp >alternator go to the > 60-anl on the firewall and then to the post of the Main Bus Fuse >Block? Yes, but mount the ANL-60 as close to Main Bus as practical. >LOCATION OF THE BATTERY BUS > >After spending hours in the archives (slow learner) I understand that the >Battery Bus belongs next to the Battery. At the moment I see only the clock, >CD player keep alive, and possibly s small emergency light on the Bat Bus. >We are talking mA's without the emergency light. The Battery Bus (BB) will >feed the E-Bus which will be supported by the SD-8 alt. Supported by the >SD-8, the E-Bus could have a continuous load of 7-10 amps and short loads to >say 15 amps. This results in an fused extended feeder carrying more than the >recommended 5-7 amps. I read that in these cases a relay, say a S704-1, can >be used like a light contactor to supply the E-Buss from the BB, Links to a >schematic were given. The link did not work for me. >? Does my description above work? > Is there a link to a schematic of the relay installation in this >situation that is current? Adding a relay to the e-bus fat-feed is illustrated at http://www.aeroelectric.com/temp/E-BusFatFeed.gif >? In the above layout can the SD-8's output feed the system using #12 wire >via the BB with, > say, a 15 amp fuse instead of using a fuselink connected to the Bat side >of the contactor? Sure . . . >A MORTAL SIN BUT BARE WITH ME > >? Let's say it is determined that the total BB and E-Bus continuous loads >are in the order > of 5-7 amps and the extended feeder to the remote mounted BB was >protected at the battery > with a 5-7 amp FUSE. Would such an installation be sinful? Probably okay but if you have an e-bus continuous load of of 7A I'd go with the relay and a 10A feeder. >? In the above scenario would the return feed from the BB to the battery >with its 5-7 amp fuse > preclude bringing the SD-8 output into the system via the remote BB? No . . . That connection as you described above would be fine. >Thanks in advance for your time and patience, your help is invaluable. My pleasure sir . . . Bob . . . ________________________________ Message 30 ____________________________________ Time: 08:51:31 PM PST US Subject: AeroElectric-List: [ Jim Jewell ] : New Email List Photo Share Available! From: Email List Photo Shares --> AeroElectric-List message posted by: Email List Photo Shares A new Email List Photo Share is available: Poster: Jim Jewell Subject: Homemade Baffle Pass Through Fitting http://www.matronics.com/photoshare/jjewell@telus.net.12.17.2003/index.html o Main Photo Share Index http://www.matronics.com/photoshare o Submitting a Photo Share If you wish to submit a Photo Share of your own, please include the following information along with your email message and files: 1) Email List or Lists that they are related to: 2) Your Full Name: 3) Your Email Address: 4) One line Subject description: 5) Multi-line, multi-paragraph description of topic: 6) One-line Description of each photo or file: Email the information above and your files and photos to: pictures@matronics.com ________________________________ Message 31 ____________________________________ Time: 09:27:48 PM PST US From: "David Carter" Subject: Re: AeroElectric-List: Airspeed Indicator --> AeroElectric-List message posted by: "David Carter" Pete, hit me with a pvt e-mail with the spreadsheet. Many thanks. David Carter DO NOT ARCHIVE ----- Original Message ----- From: "Pete & Farrell Rouse" Subject: Re: AeroElectric-List: Airspeed Indicator > --> AeroElectric-List message posted by: "Pete & Farrell Rouse" > > Jim, > > You will need to put the Pitot (Total Pressure) tap in the upper plenum, on > the top side of the baffling, and the static pressure tap below the > baffling. The static pressure difference between above the baffling and > below is what causes the cooling air to flow, thus the pressure is higher on > top of the baffling. This is true unless you have updraft cooling like > Peter Garrison's Melmoth. The easy way to remember is: > > Inlet = High Pressure > Outlet = Low Pressure > > To figure out the density of the air, use the following formula: > > rho = Pamb(psia)*144/(53.34*(Tamb(F)+459.67) > > On a 59deg F day at sea level: > > rho = 14.696*144/(53.34*(59+459.67)) > > rho = 0.07649lbm/ft > 3 > > I have created a spreadsheet to equate indicated airspeed to inches of water > pressure differential. > > I will be happy to send it to you, if you want. > > Pete Rouse > > ----- Original Message ----- > From: "Jim Sower" > To: > Subject: Re: AeroElectric-List: Airspeed Indicator > > > > --> AeroElectric-List message posted by: Jim Sower > > > > > I'm told that if I put the pitot port to the plenum and the static port > above > > the engine I can expect about 120 KIAS delta which is rumored to be the > > equivalent of about 4" H2O. I'll do the math before I do any testing to > > determine what to look for by way of IAS. > > First, I'll need to look up SL, std day rho .... Jim S. > > > > George Braly wrote: > > > > > --> AeroElectric-List message posted by: George Braly > > > > > > Jim, > > > > > > The ASI is OK. The water works but it is a bit messy and difficult. > > > > > > You should not expect to see more than about 3" to 8" of water column > > > difference. > > > > > > An ASI reads about 200 knots at 2 PSI differential. Note the difference > in > > > units!!! > > > > > > HOWEVER... you will not get meaningfully useful readings unless you > install > > > piccolo tubes on both the input and the reference (static) side of the > > > tubing that you run to the ASI. > > > > > > There are some cheap low pressure differential pressure transducers > that > > > will work nicely and are calibrated in the 0-10 or 0-15" H2O span. > > > > > > You can read the output with a volt meter. > > > > > > Regards, George > > > > > > -----Original Message----- > > > From: owner-aeroelectric-list-server@matronics.com > > > [mailto:owner-aeroelectric-list-server@matronics.com]On Behalf Of Jim > > > Sower > > > To: aeroelectric-list@matronics.com > > > Subject: Re: AeroElectric-List: Airspeed Indicator > > > > > > --> AeroElectric-List message posted by: Jim Sower > > > > > > > > > I've been there. Turned out messy and awkward for me. ASI is more > accurate > > > (better > > > granularity). I think I've got a line on a real cheap one now. > > > Jim S. > > > > > > Kingsley Hurst wrote: > > > > > > > Jim, > > > > > > > > How would a simple manometer "U tube" made of plastic tubing be? Very > > > > cheap! I don't have it to hand at this moment, but a few months ago > > > > (could even be up to 12 mths) there was discussion on this list of how > > > > to calibrate same for the checking of ASI's. > > > > > > > > Just found the following reference on the web which may be of some > > > > assistance. > > > > > > > > http://www.efunda.com/formulae/fluids/manometer.cfm#calc > > > > > > > > Regards > > > > Kingsley Hurst > > > > Europa Mono Classic 281 > > > > in Oz > > > > About to install third and final window.-- > > > > > > Jim Sower > > > Crossville, TN; Chapter 5 > > > Long-EZ N83RT, Velocity N4095T > > > > > > --- > > > Incoming mail is certified Virus Free. > > > > > > --- > > > > > > > -- > > Jim Sower > > Crossville, TN; Chapter 5 > > Long-EZ N83RT, Velocity N4095T > > > > > > ________________________________ Message 32 ____________________________________ Time: 10:03:13 PM PST US Subject: AeroElectric-List: Fat Feed Relay & Contactor From: Don Boardman --> AeroElectric-List message posted by: Don Boardman Hi Bob ... guys, Thank you for the timely reply to last night's email on No Electric Starter/System Ques. I am going with your suggestions. Your response gave me just what I needed to proceed! More questions. RELAY DIODE A question about the use of the S704-1 relay on the fat feed from the BB to the E-bus. I see how the relay is wired into the system for the SD-8 on Z-13. No Diode is involved. The relay in the Fat Feed schematic http://www.aeroelectric.com/temp/E-BusFatFeed.gif has a diode associated with it. * What's up with the diode? What type is it? Is it like the normal feed diode, a D25 or a diode like on the contactor? You remind me to heatsink the normal feed diode which allows the main bus to feed the E-bus. * Does mounting it on an aluminum shelf or firewall do the job? BATTERY CONTACTOR I purchased the "wrong" contactor a year ago . I saw prewired and went for a S701-2. I missed that it was a crossfeed contactor. I realize I need a S701-1 for my battery contactor. On the web site the pictures look like each is a 4-terminal constant duty contactor. * Can I simply use the pictures on the web site as a guide and remove the two extra diodes and add the jumper from the Bat to the coil terminal? Thanks, Don B.