---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Mon 05/19/14: 6 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 07:02 AM - Strobe Switch - New evidence (Charles Brame) 2. 07:35 AM - Re: Strobe Switch - New evidence (R&J. Curtis) 3. 07:50 AM - Re: Strobe Switch - New evidence (Sprocket) 4. 12:03 PM - Re: Strobe Switch - New evidence (Bill Watson) 5. 12:30 PM - Re: Schematic Z-17 questions (Robert L. Nuckolls, III) 6. 01:05 PM - Re: Schematic Z-17 questions (Peter Pengilly) ________________________________ Message 1 _____________________________________ Time: 07:02:14 AM PST US From: Charles Brame Subject: AeroElectric-List: Strobe Switch - New evidence Bob, et. al., Once again my strobes quit working. Suspecting another Carling switch failure, that's what I checked first. To my surprise, the switch and its connections were pristine. However, the other end of the power line, a Molex connector at the Whelen Strobe Power Pack, was the problem. The power pin had overheated to the point where the Molex connector was blackened and melted around the pin. The other pin on the connector, a ground wire, was not affected. Replaced the Molex and the system is back in operation. The mystery deepens. Charlie Brame RV-6A N11CB San Antonio ________________________________ Message 2 _____________________________________ Time: 07:35:57 AM PST US From: "R&J. Curtis" Subject: Re: AeroElectric-List: Strobe Switch - New evidence > > Once again my strobes quit working. Suspecting another Carling switch > failure, that's what I checked first. To my surprise, the switch and its > connections were pristine. However, the other end of the power line, a > Molex connector at the Whelen Strobe Power Pack, was the problem. The > power pin had overheated to the point where the Molex connector was > blackened and melted around the pin. The other pin on the connector, a > ground wire, was not affected. Replaced the Molex and the system is back > in operation. The mystery deepens. Did you check the old connector to see if (1) there were any broken strands on the connector going into either side? (2) Were the wires on the pins stripped properly and a nice gas tight crimped connection? (3) Did there appear to be any corrosion on the pins? Sometimes it is difficult to see these things after the connection is burned up, but it is worth a look. Roger ________________________________ Message 3 _____________________________________ Time: 07:50:36 AM PST US From: Sprocket Subject: Re: AeroElectric-List: Strobe Switch - New evidence Not a mystery at all. The strobe power pack is a constant-power device, which means that as the input voltage drops, the load current increases. If you have a resistive switch or connection, you'll get what's called 'thermal runaway'. This leads to burnt or charred switches, contacts or connectors. When I first discovered the problem about 7 years ago, It was the Carling switch rivets that were the root cause, but any deteriorating contact can cause it. Make it an annual inspection item for the strobe connectors and switches. Check your landing and taxi light circuits as well. Vern =================================================== Sent from my iThing. It is responsible for all gramma and typo terrors. > On May 19, 2014, at 7:01 AM, Charles Brame wrote: > > > Bob, et. al., > > Once again my strobes quit working. Suspecting another Carling switch failure, that's what I checked first. To my surprise, the switch and its connections were pristine. However, the other end of the power line, a Molex connector at the Whelen Strobe Power Pack, was the problem. The power pin had overheated to the point where the Molex connector was blackened and melted around the pin. The other pin on the connector, a ground wire, was not affected. Replaced the Molex and the system is back in operation. The mystery deepens. > > Charlie Brame > RV-6A N11CB > San Antonio > > > > ________________________________ Message 4 _____________________________________ Time: 12:03:20 PM PST US From: Bill Watson Subject: Re: AeroElectric-List: Strobe Switch - New evidence Not sure what strobe power supply you are using but I changed from one that many homebuilders were using (Plane Power?) to a Nova Electronics XPAK604X unit. It looks and mounts just like my old unit but it separates the switch from the power circuit with what I assume is an internal relay. I burned out a switch terminal on my original installation. I didn't fully understand the reasons but I swapped the original out for the Nova unit. It significantly shortened the power leads from over 10 feet to <2' (RV10). Just a thought. On 5/19/2014 10:01 AM, Charles Brame wrote: > > Bob, et. al., > > Once again my strobes quit working. Suspecting another Carling switch failure, that's what I checked first. To my surprise, the switch and its connections were pristine. However, the other end of the power line, a Molex connector at the Whelen Strobe Power Pack, was the problem. The power pin had overheated to the point where the Molex connector was blackened and melted around the pin. The other pin on the connector, a ground wire, was not affected. Replaced the Molex and the system is back in operation. The mystery deepens. > > Charlie Brame > RV-6A N11CB > San Antonio > > > ----- > No virus found in this message. > Checked by AVG - www.avg.com > > ________________________________ Message 5 _____________________________________ Time: 12:30:47 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Schematic Z-17 questions At 10:27 AM 5/19/2014, you wrote: >You mention a light weight lithium battery. This is the second time >I have seen something about use of lithium batteries in airplanes. I >would like to hear more about things like reliability, things to be >aware of, the actual storage capacity (rather than just cranking >amps) and of course, after the 787 battery issues, fire potential. >The idea using a 3 or 4 pound battery is very appealing. There's a 4-part series coming out in Kitplanes about batteries with an emphasis on evaluation of lithium products for suitability to task in aircraft. Turns out that not all lithium products are the same . . . and it goes deeper than selection of the least-hazardous chemistry. MOST commercial off the shelf examples have no battery management system yet they claim to be drop-in replacements for lead-acid. The claims go even further to suggest that a 3# lithium battery has an 18 ah 'lead acid equivalency' . . . when the 18 ah battery weighs in at 15 pounds or more. "Lead acid equivalency" speaks to engine cranking ability and glosses over shortfalls in CAPACITY. For a vfr airplane having an engine that is free of electrical dependencies, one may down-size a battery with little attention to capacity. If getting the engine started is your only concern, then the lithium chemistry can offer some enticing weight savings. But if you have any concerns for battery-only endurance, then be sure the device you pick has the capacity to meet your alternator-out endurance requirements. It also turns out that optimal battery service life is achieved by cycling the battery's level of charge between 30 and 90%. By artificially limiting available energy on a cycle-by-cycle basis (most hybrid cars do this), then they battery can last a long time. Ideally, one never runs the ship's battery down . . . but it's there if you need it. So if you set the bus voltage to limit the battery to 90% of maximum capacity, then it should last a long time. But if you ever run it down on purpose or accidently . . . then maximizing the battery's serviceability usually calls for recharging with a battery management system (BMS). Folks flying the simpler, day-vfr airplanes are encouraged to experiment with the current offerings of lithium technology http://tinyurl.com/nlamrrw This battery claims to crank as well as a 16-18 a.h lead-acid at one 6th the weight. At that price, it almost certainly has no internal BMS. On the other hand, this 2.2 pound battery claims 400+ amps cranking ability . . . and I believe it is fitted with a full-time, capable battery management system. http://tinyurl.com/lcegge5 Bob . . . ________________________________ Message 6 _____________________________________ Time: 01:05:21 PM PST US From: Peter Pengilly Subject: Re: AeroElectric-List: Schematic Z-17 questions There is also a gotcha in cold weather with lithium batteries - they don't work well (sorry I can't be specific to the type). When the battery has cold soaked at around freezing it will hardly turn over an O-360. But, a minute or two after an attempted start - I'm told 5 seconds of trying and barely cranking - the battery will have warmed itself up and happily spins the engine into life. Batteries on the firewall will probably be happy for the rest of the day (and also respond to the hair dryer in the oil door trick for 10 minutes while pre-flighting). Batteries in the aft fuselage will require the 'failed start' technique each time. No very scientific data or information on a minimum temperature when this technique doesn't work. Peter On 19/05/2014 20:27, Robert L. Nuckolls, III wrote: > > > At 10:27 AM 5/19/2014, you wrote: >> You mention a light weight lithium battery. This is the second time I >> have seen something about use of lithium batteries in airplanes. I >> would like to hear more about things like reliability, things to be >> aware of, the actual storage capacity (rather than just cranking >> amps) and of course, after the 787 battery issues, fire potential. >> The idea using a 3 or 4 pound battery is very appealing. > > There's a 4-part series coming out in Kitplanes > about batteries with an emphasis on evaluation of > lithium products for suitability to task in aircraft. > > Turns out that not all lithium products are the > same . . . and it goes deeper than selection of > the least-hazardous chemistry. > > MOST commercial off the shelf examples have no > battery management system yet they claim to be > drop-in replacements for lead-acid. The claims > go even further to suggest that a 3# lithium battery > has an 18 ah 'lead acid equivalency' . . . when > the 18 ah battery weighs in at 15 pounds or more. > > "Lead acid equivalency" speaks to engine cranking > ability and glosses over shortfalls in CAPACITY. > For a vfr airplane having an engine that is free > of electrical dependencies, one may down-size a > battery with little attention to capacity. If getting > the engine started is your only concern, then the > lithium chemistry can offer some enticing weight > savings. > > But if you have any concerns for battery-only > endurance, then be sure the device you pick > has the capacity to meet your alternator-out > endurance requirements. > > It also turns out that optimal battery service > life is achieved by cycling the battery's level > of charge between 30 and 90%. By artificially > limiting available energy on a cycle-by-cycle > basis (most hybrid cars do this), then they > battery can last a long time. > > Ideally, one never runs the ship's battery > down . . . but it's there if you need it. > So if you set the bus voltage to limit the > battery to 90% of maximum capacity, then > it should last a long time. > > But if you ever run it down on purpose or > accidently . . . then maximizing the battery's > serviceability usually calls for recharging > with a battery management system (BMS). > > Folks flying the simpler, day-vfr airplanes are > encouraged to experiment with the current offerings > of lithium technology > > http://tinyurl.com/nlamrrw > > This battery claims to crank as well as a 16-18 > a.h lead-acid at one 6th the weight. At that price, > it almost certainly has no internal BMS. > > On the other hand, this 2.2 pound battery claims > 400+ amps cranking ability . . . and I believe > it is fitted with a full-time, capable battery > management system. > > http://tinyurl.com/lcegge5 > > > Bob . . . > > ------------------------------------------------------------------------------------- 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.