---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Fri 06/05/15: 8 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 12:52 AM - Re: Alternator with no battery? (D L Josephson) 2. 04:22 AM - Re: Re: Alternator with no battery? (C&K) 3. 04:42 AM - Re: Alternator with no battery? (donjohnston) 4. 06:04 AM - Re: Re: Alternator with no battery? (Robert L. Nuckolls, III) 5. 07:10 AM - Re: Alternator with no battery? (user9253) 6. 10:02 AM - Re: Re: Alternator with no battery? (Justin Jones) 7. 01:53 PM - Re: Alternator with no battery? (donjohnston) 8. 04:12 PM - Re: Lighted Toggle Switch recommendation (DeWitt Whittington) ________________________________ Message 1 _____________________________________ Time: 12:52:08 AM PST US From: D L Josephson Subject: AeroElectric-List: Re: Alternator with no battery? The OP asked not for analysis of the reported automotive failure, but > Does anyone know what the impact of a loss of battery output (wire coming loose, > solenoid failing, battery falling out of the plane, being stolen in flight by > aliens, etc.) on the output of the alternator (with engine running at cruise > power)? > It would seem to me that if the load is less than the output of the alternator, > it should continue to put out power as long as the engine is running. In most cases it would, but there are other problems due to the high ripple component of some alternators Rotax for instance recommends a 22,000 uF capacitor specifically to smooth the ripple from their PM alternator in case the battery is not functioning. Homebuilders using low impedance capacitors with heavy screw terminals are on the right track. Some LSA manufacturers use tiny caps with thin wires, not a good recipe if you really want to get pulses of current at the full alternator rating into and out of the capacitor. ________________________________ Message 2 _____________________________________ Time: 04:22:16 AM PST US From: C&K Subject: Re: AeroElectric-List: Re: Alternator with no battery? An open battery contactor with an external regulator that is sensing voltage at the battery is going to go high voltage and be expensive. Different situation wih the sense wire on the alternator side of the contactor or an internal regulator. No guarantees but I have seen those continue to function fine when a flooded cell battery went open circuit. Ken ________________________________ Message 3 _____________________________________ Time: 04:42:23 AM PST US Subject: AeroElectric-List: Re: Alternator with no battery? From: "donjohnston" dlj04(at)josephson.com wrote: > The OP asked not for analysis of the reported automotive failure, but > > > > Does anyone know what the impact of a loss of battery output > A thousand "thank you's" kind sir! :D Read this topic online here: http://forums.matronics.com/viewtopic.php?p=443067#443067 ________________________________ Message 4 _____________________________________ Time: 06:04:25 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Alternator with no battery? Anecdoteally... BobN has suggested that some aircraft (I think he mentioned a Bonanza or Baron) can operate in an alternator-only, no-battery-in-the-circuit mode, but I don't have any knowledge of this. Perhaps the aircraft in question has a very exotic regulator. BobN can speak to this better than I. Actually, I designed several regulators for Beech wherein the a requirement in the RFQ was that the regulator, when paired with the Bonanza and Baron alternators of the time, would come alive self-excited . . . and run self excited with no battery on line. This was my first, second and third regulator designs . . . had no idea if anything 'special' was needed. As it turn out, nothing really special. What was NOT spec'd was the recovery profile from a large load change . . . especially a load dump. The overshoot would trip the ov protection . . . but the transient was still inside DO-160 qualification levels. What I discovered then was that the alternator output was stable but subject to pretty big, transient swings of voltage for large changes in load. Like turning a 100+ watt landing light on/off . . . or perhaps cycling an electrically driven, landing gear pump. Loss of battery in a stable load configuration would probably go unnoticed and represent no threat to system hardware. If the hardware is DO-160 qualified, then transients of 20 volts for one second and 40 volts for 100 milliseconds are tolerated. It's the no-battery scenario that drove selection of the test requirements spelled out in DO-160. See http://tinyurl.com/ybhvxal I'll do some playing with no-battery systems then next time I get on the bench. I have had auto mechanics tell me that if you disconnect the battery while the engine is running - DON'T DO THAT! But if you do, it will void the warranty on the electronic components of the vehicle. Yeah . . . the same physics applies here. In AUTOMOTIVE parlance, a "load dump" is battery disconnect while alternator is under heavy load . . . and the BATTERY is a substantial part of that load. i.e. the battery is badly discharged and the alternator is working hard to replace stored energy. This generates the same scenario as operating an airplane, alternator only and turning off some heavy load. Don't know about that 'void the warranty' thingy, not sure how anyone would KNOW that it was a deliberate disconnection. No doubt, some dealerships are inclined to behaviors not unlike some avionics techs of days gone by: "Gee, I think a spike got it". Most OEM equipment in cars is designed with goals equal to or greater than DO160. I've seen some specs for things like heated seat controllers. An OEM brought one out to the BEECH EMC building for testing services. The requirements document from GM was about 1/2" thick! You will notice that the old red Cessna master/alternator rocker switch does exactly the same thing. It allows the pilot to turn the alternator field on and off independent of the battery master but when you turn-off the master it turns-off the alternator field thru the mechanical interlock built into the switch. I was at Cessna when the split-rocker master switch was birthed. The functionality of the split-rocker master has been emulated in most of the Z-figures http://tinyurl.com/kdqwahq This was a time when not all appliances were vetted to DO-160 input voltage conditions . . . and the alternators could not be counted on to self-excite. Airplanes we delivered the year before with generators would start up and run very happily generator only. To this day, so will Beechjets and Hawkers. This was very EARLY in the switch from generators to alternators in aircraft and we were certainly not designers of engine drive power sources. So the split rocker was a hedge against having to re-educate pilots who knew less than we did! Now to your question - What happens if the battery somehow gets disconnected in flight due to master contactor failure, wire failure, aliens, etc? I see two possibilities: 1. The regulator keeps on regulating and buss voltage remains stable. True 99% of the time 2. The reguator can no longer keep the voltage stable and buss voltage goes up. If you have over-voltage protection, it trips and keeps your avionics from being fried but leaves you without power. (unless you have some kind of backup power source) No How your particular system will respond is anybody's guess. If you have over-voltage protection, you could test it with little risk to your avionics??? (preferable on the ground ;) It's not a guess. The physics is well known. There was discussion a while back here on the List about testing some of these hypotheses, but that would take some hefty test fixtures and some effort. I would like to play on that team if anyone is interested in a team effort. I've got some work to do at B&C this year and I'm going to rebuilt their alternator test stand with modern instrumentation and loads. I'll be working on some products that will be tested for these conditions. I don't think we're going to learn anything new but we can probably put some sense of scale and order on the anecdotal tales based on a few nuggets of physical fact and too little data on circumstance . . . like that 'shorted battery' thing in the NTSB report. I can assure you that far too little is known about what brought that airplane down. I have no foundation to argue about the shorted battery . . . but I'm exceedingly skeptical that battery failure was root cause or even a major contributor. This was an automotive conversion engine and the fact that the builder had two batteries wired in parallel in the first place raises some questions as to design goals and understanding of the physics. A short in one of two paralleled batteries would cause so anomalous system readings but it doesn't bring down the bus. Something else was going on. Bob . . . ________________________________ Message 5 _____________________________________ Time: 07:10:39 AM PST US Subject: AeroElectric-List: Re: Alternator with no battery? From: "user9253" > A short in one of two paralleled batteries would cause so anomalous system readings > but it doesn't bring down the bus. Something else was going on. Bob, this is very interesting. Can you explain the physics that apply when two batteries are connected in parallel and one of them shorts internally? I had always assumed that a low voltage on one battery would drag down the voltage of a parallel battery. Pilots who fly aircraft with two batteries need to know what symptoms will be and what action to take, if any. Thanks, Joe -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=443077#443077 ________________________________ Message 6 _____________________________________ Time: 10:02:34 AM PST US From: Justin Jones Subject: Re: AeroElectric-List: Re: Alternator with no battery? Sounds like another good case for an OVM. > On Jun 5, 2015, at 05:02, Robert L. Nuckolls, III wrote: > > Anecdoteally... > > BobN has suggested that some aircraft (I think he mentioned a Bonanza or B aron) can operate in an alternator-only, no-battery-in-the-circuit mode, but I don't have any knowledge of this. Perhaps the aircraft in question has a very exotic regulator. BobN can speak to this better than I. > > Actually, I designed several regulators > for Beech wherein the a requirement in the > RFQ was that the regulator, when paired with > the Bonanza and Baron alternators of the time, > would come alive self-excited . . . and run > self excited with no battery on line. > > This was my first, second and third > regulator designs . . . had no idea if > anything 'special' was needed. As it > turn out, nothing really special. What > was NOT spec'd was the recovery profile > from a large load change . . . especially > a load dump. The overshoot would trip > the ov protection . . . but the transient > was still inside DO-160 qualification > levels. > > What I discovered then was that the alternator > output was stable but subject to pretty > big, transient swings of voltage for large > changes in load. Like turning a 100+ > watt landing light on/off . . . or perhaps > cycling an electrically driven, landing > gear pump. > > Loss of battery in a stable load configuration > would probably go unnoticed and represent > no threat to system hardware. If the hardware > is DO-160 qualified, then transients of 20 volts > for one second and 40 volts for 100 milliseconds > are tolerated. It's the no-battery scenario > that drove selection of the test requirements > spelled out in DO-160. See > > http://tinyurl.com/ybhvxal > > > I'll do some playing with no-battery > systems then next time I get on the bench. > > > > I have had auto mechanics tell me that if you disconnect the battery while the engine is running - DON'T DO THAT! But if you do, it will void the war ranty on the electronic components of the vehicle. > > Yeah . . . the same physics applies here. > In AUTOMOTIVE parlance, a "load dump" is > battery disconnect while alternator is under > heavy load . . . and the BATTERY is a substantial > part of that load. i.e. the battery is badly > discharged and the alternator is working hard > to replace stored energy. This generates the > same scenario as operating an airplane, alternator > only and turning off some heavy load. > > Don't know about that 'void the warranty' thingy, > not sure how anyone would KNOW that it was a > deliberate disconnection. No doubt, some > dealerships are inclined to behaviors not > unlike some avionics techs of days gone by: > "Gee, I think a spike got it". > > Most OEM equipment in cars is designed with > goals equal to or greater than DO160. I've > seen some specs for things like heated seat > controllers. An OEM brought one out to the BEECH > EMC building for testing services. The requirements > document from GM was about 1/2" thick! > > > You will notice that the old red Cessna master/alternator rocker switch do es exactly the same thing. It allows the pilot to turn the alternator field on and off independent of the battery master but when you turn-off the mast er it turns-off the alternator field thru the mechanical interlock built int o the switch. > > I was at Cessna when the split-rocker master switch > was birthed. The functionality of the split-rocker > master has been emulated in most of the Z-figures > > http://tinyurl.com/kdqwahq > > This was a time when not all appliances were > vetted to DO-160 input voltage conditions . . . > and the alternators could not be counted on > to self-excite. Airplanes we delivered the > year before with generators would start up and > run very happily generator only. To this day, > so will Beechjets and Hawkers. This was very > EARLY in the switch from generators to alternators in > aircraft and we were certainly not designers > of engine drive power sources. So the split > rocker was a hedge against having to re-educate > pilots who knew less than we did! > > > > Now to your question - What happens if the battery somehow gets disconnect ed in flight due to master contactor failure, wire failure, aliens, etc? > > I see two possibilities: > 1. The regulator keeps on regulating and buss voltage remains stable. > > True 99% of the time > > > 2. The reguator can no longer keep the voltage stable and buss voltage goe s up. If you have over-voltage protection, it trips and keeps your avionics from being fried but leaves you without power. (unless you have some kind o f backup power source) > > No > > > How your particular system will respond is anybody's guess. If you have o ver-voltage protection, you could test it with little risk to your avionics? ?? (preferable on the ground ;) > > > It's not a guess. The physics is well known. > > > There was discussion a while back here on the List about testing some of t hese hypotheses, but that would take some hefty test fixtures and some effor t. I would like to play on that team if anyone is interested in a team effo rt. > > I've got some work to do at B&C this year and > I'm going to rebuilt their alternator test stand > with modern instrumentation and loads. I'll be > working on some products that will be tested for > these conditions. > > I don't think we're going to learn anything new > but we can probably put some sense of scale and > order on the anecdotal tales based on a few > nuggets of physical fact and too little data > on circumstance . . . like that 'shorted battery' > thing in the NTSB report. I can assure you that > far too little is known about what brought that > airplane down. I have no foundation to argue about > the shorted battery . . . but I'm exceedingly > skeptical that battery failure was root cause > or even a major contributor. This was an automotive > conversion engine and the fact that the builder > had two batteries wired in parallel in the first > place raises some questions as to design goals > and understanding of the physics. A short in > one of two paralleled batteries would cause so > anomalous system readings but it doesn't bring > down the bus. Something else was going on. > > > Bob . . . > > > ========================== ========= ========================== ========= ========================== ========= ========================== ========= > ________________________________ Message 7 _____________________________________ Time: 01:53:19 PM PST US Subject: AeroElectric-List: Re: Alternator with no battery? From: "donjohnston" This is very interesting. Thanks to everyone for participating. So is it safe to say that the battery is providing a type of surge suppression (or power leveling or fluctuation dampening) function in this circuit? And if it's correct that the absence of the battery could cause an over voltage situation, is there a way to mitigate that? Or is that scenario so unlikely that it's not worth protecting against? Read this topic online here: http://forums.matronics.com/viewtopic.php?p=443107#443107 ________________________________ Message 8 _____________________________________ Time: 04:12:41 PM PST US Subject: Re: AeroElectric-List: Lighted Toggle Switch recommendation From: DeWitt Whittington I'm still trying to find the exact part number, Hari, for our Honeywell, lighted rocker switches for our Sportsman. We bought them through John Stark in Columbus, Georgia, who built our panel. I'll see if Doug Hanson, my partner who is the electrical guru knows. Dee DeWitt (Dee) Whittington Richmond, VA 804-677-4849 iPhone 804-358-4333 Home On Thu, Jun 4, 2015 at 12:03 PM, Hariharan Gopalan wrote: > Hello Group > > Is anyone using lighted toggle switches? Looking for recommendations. > > Thanks > Hari > > * > > > * > > ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.