---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Mon 07/18/05: 17 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 05:53 AM - Re: Dual Fuel Pumps and EFI (Robert L. Nuckolls, III) 2. 06:47 AM - Re: Dual Fuel Pumps and EFI (Ed Anderson) 3. 07:12 AM - Re: Re: Dual Fuel Pumps and EFI (Ken) 4. 08:51 AM - Re: Re: Dual Fuel Pumps and EFI (Richard Tasker) 5. 10:28 AM - Re: Re: OVP, Alternators, and stuff (Eric Ruttan) 6. 10:30 AM - battery contactor alternative (ray.stlaurent@vsea.com) 7. 12:16 PM - Re: How to test the OV? (Vincent Welch) 8. 02:24 PM - EI V/A Discharge light (david caswell) 9. 03:21 PM - Re: DC fans problem. (Eric M. Jones) 10. 03:25 PM - Re: Re: OVP crowbar false triggering (Robert L. Nuckolls, III) 11. 03:27 PM - Re: EI V/A Discharge light (Robert L. Nuckolls, III) 12. 03:29 PM - Re: How to test the OV? (Robert L. Nuckolls, III) 13. 03:39 PM - Re: OVP, Alternators, and stuff (Eric M. Jones) 14. 06:46 PM - Re: EI V/A Discharge light (david caswell) 15. 07:04 PM - Loadmeter (plaurence@the-beach.net) 16. 07:13 PM - Re: EI V/A Discharge light (William) 17. 09:09 PM - Re: EI V/A Discharge light (Robert L. Nuckolls, III) ________________________________ Message 1 _____________________________________ Time: 05:53:25 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Dual Fuel Pumps and EFI --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" At 06:19 PM 7/16/2005 -0700, you wrote: >--> AeroElectric-List message posted by: "John Burnaby" > >I want to wire 2 fuel pumps, for an EFI system, into AEC schematic Z-14 so >that when fuel pressure drops below a preset psi, the secondary pump turns >on and locks on ,and I want to have manual overides. How does your engine behave under in-flight fuel starvation? Does it present a situation that is difficult or dangerous to recover from? The reason I ask is because systems with automatic features generally have parts counts several times that of a simple manual system. In all of the airplanes I fly, fuel starvation due to a misplacement of fuel selector valve or failure of primary pump will recover in seconds after corrective action on the part of the pilot with very little loss of altitude. >I was told pressure switches are not that accurate re repeatability and >that I would be better off with a pressure transducer. I'm not sure what a >transducer is and how it would be integrated into a switch that would >control the pumps, but I'm guessing that the pressure sensing device >(transducer?) would be wired into some sort of locking relay. I'll suggest a careful consideration of added value for installing this kind of system. Automatic or "smart" systems can have a way of lulling a pilot into ill-placed confidence or worse, complacency. They certainly add to cost of ownership in that there's just that much "stuff" to buy, install, maintain, and break. Bob . . . ________________________________ Message 2 _____________________________________ Time: 06:47:20 AM PST US From: "Ed Anderson" Subject: Re: AeroElectric-List: Dual Fuel Pumps and EFI --> AeroElectric-List message posted by: "Ed Anderson" I agree with Bob regarding the advisability of adding "Smart" fuel pump control, additional parts = more chances for a malfunction/failure. I have flown 6 years with an all electrical set up. I have two high pressure fuel pumps for my EFI fuel system. Both are on for take off and landings (as well as a boost pump). At altitude I turn one of the EFI pumps off - should it fail, it would take no more than a couple of seconds to switch the back up on and at altitude that should pose little problem. During take off and landing would be the phase when a fraction of a second could make a difference - that of course is why both are on during those phases of operation. Don't complicate your fuel system, keep it simple. FWIW Ed Anderson RV-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com ----- Original Message ----- From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Dual Fuel Pumps and EFI > --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" > > > At 06:19 PM 7/16/2005 -0700, you wrote: > >>--> AeroElectric-List message posted by: "John Burnaby" >> >> >>I want to wire 2 fuel pumps, for an EFI system, into AEC schematic Z-14 so >>that when fuel pressure drops below a preset psi, the secondary pump turns >>on and locks on ,and I want to have manual overides. > > How does your engine behave under in-flight fuel starvation? Does it > present a situation that is difficult or dangerous to recover from? > The reason I ask is because systems with automatic features generally > have parts counts several times that of a simple manual system. In > all of the airplanes I fly, fuel starvation due to a misplacement of > fuel selector valve or failure of primary pump will recover in seconds > after corrective action on the part of the pilot with very little loss > of altitude. > > >>I was told pressure switches are not that accurate re repeatability and >>that I would be better off with a pressure transducer. I'm not sure what a >>transducer is and how it would be integrated into a switch that would >>control the pumps, but I'm guessing that the pressure sensing device >>(transducer?) would be wired into some sort of locking relay. > > I'll suggest a careful consideration of added value for installing > this kind of system. Automatic or "smart" systems can have a way > of lulling a pilot into ill-placed confidence or worse, complacency. > They certainly add to cost of ownership in that there's just that > much "stuff" to buy, install, maintain, and break. > > Bob . . . > > > ________________________________ Message 3 _____________________________________ Time: 07:12:06 AM PST US From: Ken Subject: Re: AeroElectric-List: Re: Dual Fuel Pumps and EFI --> AeroElectric-List message posted by: Ken I don't follow Eggenfellner info but I have heard that their early pressure switches were not very compatible with gasoline and had to be replaced due to leakage. Injected engines with a fuel return should recover power very quickly anyway so I've kept my installation simple. I may run both pumps when close to the ground if that proves feasible. The pump output is regulated at 38 psi above manifold pressure as I recall so I can see the temptation to use a dual port sensor. A dual port sensor would be nice for the fuel pressure gauge but I'm not aware of an affordable fuel compatible unit. A dual port sensor has the additional failure mode of leaking fuel into the intake manifold as well though. What sensors are the oem car manufacturers using for the systems that use pcm fuel pump control for returnless pressure regulation.? .. However I'd also think that a one port sensor/switch would be fine if it triggered at something like 20 psi with +/- 5 or 10psi accuracy. I don't see why you'd need accurate repeatability?? The manifold can't draw much more than about 13 psi vacuum below ambient. Presumably you'd feed the sensor with a small orifice to help dampen fluctuations. I dunno, if the engine isn't running correctly I'd imagine you are going to turn that second pump on manually anyway... Ken glaesers wrote: >--> AeroElectric-List message posted by: "glaesers" > >See the Aux Fuel Pump circuit on the Engine Electrical Architecure diagram >on this page: >http://www.wideopenwest.com/~glaesers/RV7A/RV7A_Electrical.htm >It does exactly what you want - see the explanation in the OPERATION box. > >This is an adaptation of the electrical system architecture from the >Eggenfeller Subaru installation manual. Their design uses a single 4PDT >switch to control the power to the engine. I want switch reduncancy, so I >use more (and less expensive) switches. > >Eggenfeller supplies the fuel pressure sensor switch. I don't have one yet >so I don't know what kind of sensor it is (mechanical or electronic), but >I've been on their Yahoo list for over a year, and no one has ever reported >problems. I'm sure you could contact Jan Eggenfeller to get the part number >if you are interested. > >A transducer is a generic term for converting one form of energy to another >(in this case pressure to electrical). So any pressure switch is a >transducer, but I suspect the comment was about the type of transducer (ie. >mechanical vs. electronic sensor). Dick Tasker (who participates on this >list) would be a good source for info - his company makes sensors. > >Dennis Glaeser >RV7A Empennage > > >--> AeroElectric-List message posted by: "John Burnaby" > > >I want to wire 2 fuel pumps, for an EFI system, into AEC schematic Z-14 so >that >when fuel pressure drops below a preset psi, the secondary pump turns on and >locks on ,and I want to have manual overides. > >I was told pressure switches are not that accurate re repeatability and that >I >would be better off with a pressure transducer. I'm not sure what a >transducer >is and how it would be integrated into a switch that would control the >pumps, >but I'm guessing that the pressure sensing device (transducer?) would be >wired >into some sort of locking relay. > >I welcome any ideas. > >Thanks, >John > > > > ________________________________ Message 4 _____________________________________ Time: 08:51:31 AM PST US From: Richard Tasker Subject: Re: AeroElectric-List: Re: Dual Fuel Pumps and EFI --> AeroElectric-List message posted by: Richard Tasker The pressure switch Jan supplies is a mechanical sensor (I know because I have an Eggenfellner Subaru engine). For most applications, including this one, a mechanical sensor is more than adequate. The only real reason to use an electronic sensor in a switch would be if you are trying to control or monitor something to a very high degree of accuracy - such as on a process control application, etc. Another email in this thread mentioned that Eggenfellner had problems with this switch. That is not quite true. The first switch supplied had problems with gasoline (an internal o-ring failed) but the new switch now supplied is designed to work with hydrocarbons and works fine (all previous switches were replaced by Jan with the new one well over a year or two ago). Dick Tasker glaesers wrote: >--> AeroElectric-List message posted by: "glaesers" > >See the Aux Fuel Pump circuit on the Engine Electrical Architecure diagram >on this page: >http://www.wideopenwest.com/~glaesers/RV7A/RV7A_Electrical.htm >It does exactly what you want - see the explanation in the OPERATION box. > >This is an adaptation of the electrical system architecture from the >Eggenfeller Subaru installation manual. Their design uses a single 4PDT >switch to control the power to the engine. I want switch reduncancy, so I >use more (and less expensive) switches. > >Eggenfeller supplies the fuel pressure sensor switch. I don't have one yet >so I don't know what kind of sensor it is (mechanical or electronic), but >I've been on their Yahoo list for over a year, and no one has ever reported >problems. I'm sure you could contact Jan Eggenfeller to get the part number >if you are interested. > >A transducer is a generic term for converting one form of energy to another >(in this case pressure to electrical). So any pressure switch is a >transducer, but I suspect the comment was about the type of transducer (ie. >mechanical vs. electronic sensor). Dick Tasker (who participates on this >list) would be a good source for info - his company makes sensors. > >Dennis Glaeser >RV7A Empennage > > >--> AeroElectric-List message posted by: "John Burnaby" > > >I want to wire 2 fuel pumps, for an EFI system, into AEC schematic Z-14 so >that >when fuel pressure drops below a preset psi, the secondary pump turns on and >locks on ,and I want to have manual overides. > >I was told pressure switches are not that accurate re repeatability and that >I >would be better off with a pressure transducer. I'm not sure what a >transducer >is and how it would be integrated into a switch that would control the >pumps, >but I'm guessing that the pressure sensing device (transducer?) would be >wired >into some sort of locking relay. > >I welcome any ideas. > >Thanks, >John > > > > ________________________________ Message 5 _____________________________________ Time: 10:28:30 AM PST US From: Eric Ruttan Subject: Re: AeroElectric-List: Re: OVP, Alternators, and stuff --> AeroElectric-List message posted by: Eric Ruttan >3) E-bus Diodes--Use a big fat Schottky for bus isolation. The arguments >against not doing this trigger my Attention Deficit Disorder--knocking me >into the ozone. What were we discussing....? > > Are you admitting you have no technical reasons to drive this implementation? And it has not been tested? And it belongs on an airplane why? >4) LEDs--Automakers are planning to introduce LED headlights in the 2008 >model year. Then the efficacy will be 100 lumens-per-watt (as good as >fluorescents). Bet on it. > >More later, only 91 more theses to go.... > >Eric M. Jones > Eric; Can you post a source for your LED proclamations? In all my conversations (monthly) with lighting engineers at Visteon, Delphi and Siemens (all located right here) White LEDs are failing badly in all areas that drive implementation. But perhaps you have data from a better source than I? ________________________________ Message 6 _____________________________________ Time: 10:30:34 AM PST US Subject: AeroElectric-List: battery contactor alternative From: ray.stlaurent@vsea.com 0.12 MISSING_HEADERS Missing To: header --> AeroElectric-List message posted by: ray.stlaurent@vsea.com If the purpose of the battery contactor is to isolate the electrical system from a large current source, the battery, what if instead a high current solid state relay such as one of Erics Powerlinks connected the battery to the electrical system. Since the Powerlink is unidirectional, a power shottky diode could used to handle the much lower current return flow requirements to the battery. Or have I missed something fundamental? -- Ray ________________________________ Message 7 _____________________________________ Time: 12:16:34 PM PST US From: "Vincent Welch" Subject: RE: AeroElectric-List: How to test the OV? --> AeroElectric-List message posted by: "Vincent Welch" Mike, I tested mine with a variable power supply. I put the OVP is series with a current limiting resistor and the power supply. I put a voltmeter across the resitor and slowly increased the voltage until the SCR tripped and the voltage across the resistor jumped up. I believe that it tripped at 16.5 volts. This was tested on the bench before I ever installed in on the plane. Vince >From: "Stewart, Michael (ISS Atlanta)" >Reply-To: aeroelectric-list@matronics.com >To: >Subject: AeroElectric-List: How to test the OV? >Date: Fri, 15 Jul 2005 11:30:07 -0400 > >--> AeroElectric-List message posted by: "Stewart, Michael (ISS Atlanta)" > > >How do I test my AEC OVP module? I have an internally regulated alt. and >the >I have searched the archives. And cant find the answer. I have the >pre-wired solenoid with the OV crowbar. S701-2 >http://www.bandc.biz/S701-2.html > > >Thanks >Mike >Do not archive > > ________________________________ Message 8 _____________________________________ Time: 02:24:42 PM PST US From: david caswell Subject: AeroElectric-List: EI V/A Discharge light --> AeroElectric-List message posted by: david caswell Hi Bob, I have a new L-40 Alternator and a new LR3C-14 regulator. Architecture is basically Z-11. With engine running and no loads, voltage on EI volt/amp instrument is 13.3V (approx) As loads are added the EI volt/amp instrument shows the Volts (bus voltage) reducing as I increase loads until at 12.5 V the EI instrument discharge light comes on (it is set to come on when bus voltage is below 12.6 volts) The low voltage warning light hooked to the LR3C regulator does not come on when the EI light comes on, but does come on when engine is not running and Alternator switch is ON. The external shunt is hooked up on the alternator lead. Any suggestions as to what I may have done wrong? Is this an EI problem? Thank you, in advance. David Caswell RV7 805 DJ 1st flight 7/17/05 ________________________________ Message 9 _____________________________________ Time: 03:21:04 PM PST US From: "Eric M. Jones" Subject: AeroElectric-List: Re: DC fans problem. --> AeroElectric-List message posted by: "Eric M. Jones" --> AeroElectric-List message posted by: "John Swartout" >Eric, would you recommend one of these Transient Voltage Suppressors >[Bidirectional transorb P6KE18CA] for >a Commercial Aviation Products 12VDC flap actuator (Model D145-00-36-3)? >John John, Yes, I would.... Although Bob N. objects to sprinking these things around, he comes from a large family of muggles who don't believe in wizardry at all.. Regards, Eric M. Jones www.PerihelionDesign.com 113 Brentwood Drive Southbridge MA 01550-2705 (508) 764-2072 ________________________________ Message 10 ____________________________________ Time: 03:25:48 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: OVP crowbar false triggering --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" At 11:58 PM 7/15/2005 -0700, you wrote: >--> AeroElectric-List message posted by: "Thomas Johnson" > >Bob N, > >I would be delighted to put my hands on your airplane with some test >equipment to see if we can understand why it's so different. > >I would like that too but I am in SoCal and you are not (COME ON >OUT! I'll buy lunch!). What do you think is the minimum requirement for >test equipment to get some useful data on this? I think the answer will >be "more than I can afford" but it does not hurt to ask. my all time favorite investigative tool is the Tektronix TDS210/220 series digital 'scopes. They're small, light, very fast and will dump a screen to a printer. I have a portable battery/inverter pak that will support the scope and an inkjet printer for use in the field. >Do you still have the old module? If so, you can send it back to me for a >no-charge upgrade. > >Yes, I have all of them. I built four but it was really 2 X 2 >versions. I will round them up and send them to the address on your web >site if I don't hear otherwise. I do not need you to send replacements >for my sake, I am quite happy with the "MOS-FET miracle" I am flying >now. I would be willing try out new versions in my airplane and report >the results. Your experience has never included an OVM-14 from myself or B&C? Can you send me a schematic of the mos-fet version? > to see which one is the "rose wood stake". > >Please forgive my ignorance. I know what a "rosetta stone" is, but I do >not know what "rose wood stake" means. It always hurts to ask this kind >of question but if I don't ask I will never know. A rose wood stake through the heart is the sure fire way to dispatch a vampire. Crosses and garlic may chase them away but a rose wood stake is the ultimate cure. This depends on what part of the world your vampire lore is crafted . . . some say ash is the best material, others call for any ol' wood stake. "Rose wood" has a better 'ring' to it . . . Bob . . . Bob . . . ________________________________ Message 11 ____________________________________ Time: 03:27:59 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: EI V/A Discharge light --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" At 02:23 PM 7/18/2005 -0700, you wrote: >--> AeroElectric-List message posted by: david caswell > > >Hi Bob, > >I have a new L-40 Alternator and a new LR3C-14 regulator. Architecture >is basically Z-11. With engine running and no loads, voltage on EI >volt/amp instrument is 13.3V (approx) As loads are added the EI volt/amp >instrument shows the Volts (bus voltage) reducing as I increase loads >until at 12.5 V the EI instrument discharge light comes on (it is set to >come on when bus voltage is below 12.6 volts) The low voltage warning >light hooked to the LR3C regulator does not come on when the EI light >comes on, but does come on when engine is not running and Alternator >switch is ON. The external shunt is hooked up on the alternator lead. The EI reading for alternator output is also probably zero. >Any suggestions as to what I may have done wrong? The alternator is not producing any output. I suggest you troubleshoot per B&C instructions, per note 8 of Appendix-Z. Bob . . . ________________________________ Message 12 ____________________________________ Time: 03:29:50 PM PST US From: "Robert L. Nuckolls, III" Subject: RE: AeroElectric-List: How to test the OV? --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" At 03:15 PM 7/18/2005 -0400, you wrote: >--> AeroElectric-List message posted by: "Vincent Welch" > > >Mike, > >I tested mine with a variable power supply. I put the OVP is series with a >current limiting resistor and the power supply. I put a voltmeter across >the resitor and slowly increased the voltage until the SCR tripped and the >voltage across the resistor jumped up. I believe that it tripped at 16.5 >volts. This was tested on the bench before I ever installed in on the >plane. That's what it's supposed to do. Suggest you do this every annual on ANY form of ov protection. I worked a case of smoked electronics many moons ago where the ov relay failed to catch a runaway alternator. A lead wire had broken off inside the relay at some undertmined time in the past rendering the ov protection inoperative. Bob . . . ________________________________ Message 13 ____________________________________ Time: 03:39:48 PM PST US From: "Eric M. Jones" Subject: AeroElectric-List: Re: OVP, Alternators, and stuff 0.60 COMMA_SUBJECT Subject is like 'Re: FDSDS, this is a subject' --> AeroElectric-List message posted by: "Eric M. Jones" --> AeroElectric-List message posted by: Eric Ruttan ericruttan@chartermi.net Hi Eric >>3) E-bus Diodes--Use a big fat Schottky for bus isolation. The arguments >>against not doing this trigger my Attention Deficit Disorder--knocking me >>into the ozone. What were we discussing....? >> >> >Are you admitting you have no technical reasons to drive this >implementation? And it has not been tested? And it belongs on an >airplane why? No. When I admit something, my lower lip starts to tremble and my palms sweat. I was refering to the fact that the Schottky subject has been argued out. I sell PowerSchottkies by the truckload. >4) LEDs--Automakers are planning to introduce LED headlights in the 2008 >model year. Then the efficacy will be 100 lumens-per-watt (as good as >fluorescents). Bet on it. >Eric M. Jones >Eric; >Can you post a source for your LED proclamations? In all my >conversations (monthly) with lighting engineers at Visteon, Delphi and >Siemens (all located right here) White LEDs are failing badly in all >areas that drive implementation.But perhaps you have data from a better >source than I? Proclamation? No, that was an "Optimistic Futurist Pronunciamento". Check out Lamina, Lumileds (of course), Nichia, Cree, and LEDs magazine (online). The big guys generally move too slowly. The problem with white phosphors is real but is being addressed in a variety of ways. Very technical publications are online but they usually charge for them. The future in LEDs is almost guaranteed because the theoretical efficiency is better than almost any other light source. Expect LEDs to double in efficiency for each of the next three years. But as they say--your mileage may vary.... Regards, Eric M. Jones www.PerihelionDesign.com 113 Brentwood Drive Southbridge MA 01550-2705 (508) 764-2072 When trouble arises and things look bad, there is always one individual who perceives a solution and is willing to take command. Very often, that individual is crazy. --Dave Barry ________________________________ Message 14 ____________________________________ Time: 06:46:09 PM PST US From: david caswell Subject: Re: AeroElectric-List: EI V/A Discharge light --> AeroElectric-List message posted by: david caswell Bob, Thanks for input. I will perform diagnostic test per note 8 when I get back to plane. But I'm somewhat baffled by why the "low voltage warning light" from the LR3C regulator doesn't come on if there is zero output from the alternator....I thought that was the purpose of the "warning light"? "Robert L. Nuckolls, III" wrote: --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" At 02:23 PM 7/18/2005 -0700, you wrote: >--> AeroElectric-List message posted by: david caswell > > >Hi Bob, > >I have a new L-40 Alternator and a new LR3C-14 regulator. Architecture >is basically Z-11. With engine running and no loads, voltage on EI >volt/amp instrument is 13.3V (approx) As loads are added the EI volt/amp >instrument shows the Volts (bus voltage) reducing as I increase loads >until at 12.5 V the EI instrument discharge light comes on (it is set to >come on when bus voltage is below 12.6 volts) The low voltage warning >light hooked to the LR3C regulator does not come on when the EI light >comes on, but does come on when engine is not running and Alternator >switch is ON. The external shunt is hooked up on the alternator lead. The EI reading for alternator output is also probably zero. >Any suggestions as to what I may have done wrong? The alternator is not producing any output. I suggest you troubleshoot per B&C instructions, per note 8 of Appendix-Z. Bob . . . ________________________________ Message 15 ____________________________________ Time: 07:04:54 PM PST US From: plaurence@the-beach.net Subject: AeroElectric-List: Loadmeter --> AeroElectric-List message posted by: plaurence@the-beach.net Bob N. , Do you have a source for an Alternator loadmeter? I believe you once carried this product. Peter Laurence ________________________________ Message 16 ____________________________________ Time: 07:13:40 PM PST US From: "William" Subject: Re: AeroElectric-List: EI V/A Discharge light --> AeroElectric-List message posted by: "William" In a test I did, when the freshly charged battery is connected to the LR-3, and only the battery solenoid was being drawn from the battery, it took a couple of minutes for the voltage to drop enough for the LV light to start flashing. If there is any load on the system, I expect that it would come on faster. Bill Schertz KIS Cruiser # 4045 ----- Original Message ----- From: "david caswell" Subject: Re: AeroElectric-List: EI V/A Discharge light > --> AeroElectric-List message posted by: david caswell > > > Bob, > > Thanks for input. I will perform diagnostic test per note 8 when I get > back to plane. But I'm somewhat baffled by why the "low voltage warning > light" from the LR3C regulator doesn't come on if there is zero output > from the alternator....I thought that was the purpose of the "warning > light"? > > "Robert L. Nuckolls, III" wrote: > --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" > > At 02:23 PM 7/18/2005 -0700, you wrote: > >>--> AeroElectric-List message posted by: david caswell >> >> >>Hi Bob, >> >>I have a new L-40 Alternator and a new LR3C-14 regulator. Architecture >>is basically Z-11. With engine running and no loads, voltage on EI >>volt/amp instrument is 13.3V (approx) As loads are added the EI volt/amp >>instrument shows the Volts (bus voltage) reducing as I increase loads >>until at 12.5 V the EI instrument discharge light comes on (it is set to >>come on when bus voltage is below 12.6 volts) The low voltage warning >>light hooked to the LR3C regulator does not come on when the EI light >>comes on, but does come on when engine is not running and Alternator >>switch is ON. The external shunt is hooked up on the alternator lead. > > The EI reading for alternator output is also probably zero. > > >>Any suggestions as to what I may have done wrong? > > The alternator is not producing any output. I suggest you > troubleshoot per B&C instructions, per note 8 of Appendix-Z. > > Bob . . . > > > ________________________________ Message 17 ____________________________________ Time: 09:09:45 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: EI V/A Discharge light --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" At 06:44 PM 7/18/2005 -0700, you wrote: >--> AeroElectric-List message posted by: david caswell > > >Bob, > >Thanks for input. I will perform diagnostic test per note 8 when I get >back to plane. But I'm somewhat baffled by why the "low voltage warning >light" from the LR3C regulator doesn't come on if there is zero output >from the alternator....I thought that was the purpose of the "warning light"? Yes . . . but if there are very light loads on the battery, the battery might support the bus above the low voltage light trip point. Nominally they're set for 13.0 volts. Easy to check on the bench with a power supply and good meter. Further, do not assume that because all the various voltmeters are hooked to "the system" that they're all going to read the same voltage for a variety of reasons that include votlage drop in system conductors and instrument accuracy. The best check is to measure the trip points and calibration of each instrument independently before you start chasing down other variables in the system. The LR-3 trip point is set up by precision resistors and a precision reference device. It MIGHT be that one of the resistors is a wrong value but I would be skeptical . . . the 13.0 plus or minus 0.2 volt is an acceptance test parameter at B&C. Bob . . .