---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Thu 10/09/14: 13 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 06:49 AM - Re: Lithium Battery Article in Kitplanes (Robert L. Nuckolls, III) 2. 07:50 AM - Re: Lithium Battery Article in Kitplanes (Ralph Finch) 3. 08:05 AM - Re: Lithium Battery Article in Kitplanes (Robert L. Nuckolls, III) 4. 08:08 AM - Should a tripped circuit breaker be reset in flight? (user9253) 5. 08:35 AM - Re: Connector for shielded wire (bmwr606) 6. 08:41 AM - Re: Lithium Battery Article in Kitplanes (Ken Ryan) 7. 09:39 AM - Re: Should a tripped circuit breaker be reset in flight? (Robert L. Nuckolls, III) 8. 10:36 AM - Re: Should a tripped circuit breaker be reset in flight? (rv8builder) 9. 01:40 PM - Re: Should a tripped circuit breaker be reset in flight? (stearman456) 10. 03:01 PM - are twisted pairs necessary for RS-232? (Ken Ryan) 11. 04:13 PM - Re: are twisted pairs necessary for RS-232? (Henry Hallam) 12. 04:32 PM - Re: are twisted pairs necessary for RS-232? (Ken Ryan) 13. 05:01 PM - Re: are twisted pairs necessary for RS-232? (Henry Hallam) ________________________________ Message 1 _____________________________________ Time: 06:49:46 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Lithium Battery Article in Kitplanes At 22:17 2014-10-06, you wrote: > >There is an article by Dean Sigler in the November 2014 issue of >KitPlanes Magazine discussing lithium batteries. There is a picture >of lithium batteries being charged inside of a fireplace. Should >aircraft lithium battery boxes be made of firebrick? :) Had a great vacation trip punctuated by broken airplanes and overnight stays in travel at both ends . . . what are the odds? Got a look at the article cited. This is pretty much an academic assemblage of published facts about the various lithium products being studied and tried in MOTIVE POWER applications where energy density and charge/discharge protocols are much more demanding. The article is probably accurate but minimally relevant to what we're doing . . . or proposing to do with lithium battery products. Getting a lithium battery to burn is like any other catastrophic energy release in that it takes a combination of stacked conditions. In the case of an ENGINE CRANKING / STANDBY POWER battery, the first condition we'll strive to minimize is the choice of chemistries. My preliminary findings working with the 26650 liFe cells purchased off eBay suggest that their ratings, and coincidentally their in-service risks for abuse, are strongly influenced by the boundaries on charge/recharge limits. Many articles I've read suggest that optimum battery life is achieved if the cells are cycled between about 80 and 20 percent of their chemical energy limits. The hybrid vehicles program their battery management systems to keep routine cycling of the cell packs within these or similar limits thus accepting a designed-in de-rating of battery capacity. This de-rating along with choice of a chemistry with the most robust resistance to conflagration suggest that fire-brick battery boxes are probably overkill. Lowered risks for LiFe fire not-withstanding, the lithium products finding their way onto TC aircraft ARE being housed in enclosures that ASSUME a potential for the worst . . . said enclosures are designed to contain a battery fire and vent products of combustion overboard. Know too that these offerings have a significant proportion of procurement expense tied up in the battery management system electronics! Emacs! http://tinyurl.com/l6xbev7 As of this date, I'me aware of no similar prophylactics against catastrophic failure being offered to the OBAM aviation community. My cursory studies of the lithium question have produced some enlightenment and mild surprises . . . but the data gathering methodology was too coarse . . . it seems that differences as small as 0.1 volts per cell in charging voltage can have a large effect on energy stored. I've go more cells ordered and I'm assembling better data gathering tools. One thing I can offer at this stage of the study is to strongly object to any marketing of a lithium product with words that speak to "lead-acid equivalency" . . . these are an entirely different breed of cat and to suggest that an end user can expect performance and maintenance issues to be a matter of drop-in equivalency is at best disingenuous and at worst a tad fraudulent. To the snow-mobiler or biker who's interests are largely limited to engine cranking and service life, the loose application of words like 'equivalency' is not terribly egregious. Airplanes are be VERY different in operational expectations, system integration and failure modes management. In the mean time, know that the article cited in the subject line of this tread has little significance to the issues we're wrestling with here on the List. Watch this space . . . Bob . . . ________________________________ Message 2 _____________________________________ Time: 07:50:10 AM PST US From: Ralph Finch Subject: Re: AeroElectric-List: Lithium Battery Article in Kitplanes I'm a bit puzzled as to why we, the E/AB community, would seriously consider Lithium batteries for the main battery. To save weight or space? The savings are insignificant and the unknowns and risks are not insignificant. Lithium chemistry makes sense for highly portable electronics (laptops, tablets, phones) but not so much for us. Sure, we DO build and fly *experimental* aircraft, but there's a limit to how much experimenting most will do. The more proven non-flooded Lead-based batteries are very safe and convenient and I use them on both my certificated Aircoupe and the RV-9A that will hopefully be flying next year. Ralph Finch On Thu, Oct 9, 2014 at 6:48 AM, Robert L. Nuckolls, III < nuckolls.bob@aeroelectric.com> wrote: > At 22:17 2014-10-06, you wrote: > > > There is an article by Dean Sigler in the November 2014 issue of KitPlanes > Magazine discussing lithium batteries. There is a picture of lithium > batteries being charged inside of a fireplace. Should aircraft lithium > battery boxes be made of firebrick? :) > > > Had a great vacation trip punctuated by broken > airplanes and overnight stays in travel at both > ends . . . what are the odds? > > Got a look at the article cited. This is pretty > much an academic assemblage of published facts > about the various lithium products being studied > and tried in MOTIVE POWER applications where > energy density and charge/discharge protocols are > much more demanding. The article is probably > accurate but minimally relevant to what we're > doing . . . or proposing to do with lithium battery > products. > > Getting a lithium battery to burn is like any > other catastrophic energy release in that it > takes a combination of stacked conditions. In > the case of an ENGINE CRANKING / STANDBY POWER > battery, the first condition we'll strive to > minimize is the choice of chemistries. > > My preliminary findings working with the 26650 > liFe cells purchased off eBay suggest that their > ratings, and coincidentally their in-service > risks for abuse, are strongly influenced by the > boundaries on charge/recharge limits. Many articles > I've read suggest that optimum battery life is > achieved if the cells are cycled between about > 80 and 20 percent of their chemical energy limits. > The hybrid vehicles program their battery management > systems to keep routine cycling of the cell packs > within these or similar limits thus accepting > a designed-in de-rating of battery capacity. > > This de-rating along with choice of a chemistry > with the most robust resistance to conflagration > suggest that fire-brick battery boxes are probably > overkill. Lowered risks for LiFe fire not-withstanding, > the lithium products finding their way onto TC > aircraft ARE being housed in enclosures that > ASSUME a potential for the worst . . . said > enclosures are designed to contain a battery > fire and vent products of combustion overboard. > > Know too that these offerings have a significant > proportion of procurement expense tied up in the > battery management system electronics! > > > [image: Emacs!] > > http://tinyurl.com/l6xbev7 > > As of this date, I'me aware of no similar > prophylactics against catastrophic failure being > offered to the OBAM aviation community. > > My cursory studies of the lithium question have produced > some enlightenment and mild surprises . . . but the > data gathering methodology was too coarse . . . it seems > that differences as small as 0.1 volts per cell in charging > voltage can have a large effect on energy stored. I've > go more cells ordered and I'm assembling better data > gathering tools. > > One thing I can offer at this stage of the study is > to strongly object to any marketing of a lithium product > with words that speak to "lead-acid equivalency" . . . > these are an entirely different breed of cat and to > suggest that an end user can expect performance and > maintenance issues to be a matter of drop-in equivalency > is at best disingenuous and at worst a tad fraudulent. > > To the snow-mobiler or biker who's interests are largely > limited to engine cranking and service life, the loose > application of words like 'equivalency' is not terribly > egregious. Airplanes are be VERY different in operational > expectations, system integration and failure modes management. > > In the mean time, know that the article cited in the > subject line of this tread has little significance to > the issues we're wrestling with here on the List. > > Watch this space . . . > > > Bob . . . > ________________________________ Message 3 _____________________________________ Time: 08:05:39 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Lithium Battery Article in Kitplanes At 09:48 2014-10-09, you wrote: >I'm a bit puzzled as to why we, the E/AB community, would seriously >consider Lithium batteries for the main battery. To save weight or >space? The savings are insignificant and the unknowns and risks are >not insignificant. Lithium chemistry makes sense for highly portable >electronics (laptops, tablets, phones) but not so much for us. > >Sure, we DO build and fly *experimental* aircraft, but there's a >limit to how much experimenting most will do. The more proven >non-flooded Lead-based batteries are very safe and convenient and I >use them on both my certificated Aircoupe and the RV-9A that will >hopefully be flying next year. A lucid deliberation my friend . . . based on my own experience and personal design goals for seeking the 'elegant solution', I have no foundation for a contrary argument. But until we know as much as can be discovered about these critters, arguments proposing any design goal will be on shaky foundation. Bob . . . ________________________________ Message 4 _____________________________________ Time: 08:08:23 AM PST US Subject: AeroElectric-List: Should a tripped circuit breaker be reset in flight? From: "user9253" There is an article in the October 2014 issue of Sport Aviation on page 92 titled, "I'll Never Do That Again". The author experienced an avionics failure while in IFR conditions. Other pilots in similar emergency situations have crashed. This pilot was very experienced. After briefly losing control, he was able to use backup instruments and land. While safely on the ground, he noticed a popped circuit breaker and reset it. It immediately tripped again, accompanied by an unusual smell. The pilot wrote, "I will never reset a breaker in the air. I did not have a fire, but I clearly was cooking something while I was on the ramp. Flames on the ground are a problem. Flames in the air are deadly." Take away the resettable feature of circuit breakers and they have no advantage (in most cases) over fuses, other than the cool factor of the appearance of a neat row of breakers. Fuses cost less, weigh less, and never fail to open when overloaded. Joe -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=431678#431678 ________________________________ Message 5 _____________________________________ Time: 08:35:24 AM PST US Subject: AeroElectric-List: Re: Connector for shielded wire From: "bmwr606" unless you need to remove the wings on a regular basis, leave a "service loop" at the wing root ... no chance of a connector failure or corrosion but if a future need for wing removal arises you can cut the service loop and add a connector at that time i usually leave about a 4 inch diameter service loop Read this topic online here: http://forums.matronics.com/viewtopic.php?p=431680#431680 ________________________________ Message 6 _____________________________________ Time: 08:41:32 AM PST US From: Ken Ryan Subject: Re: AeroElectric-List: Lithium Battery Article in Kitplanes I am comfortable using Lithium batteries based on the many, many thousands that are currently in use in snowmachines, motorcycles, etc., and the many that are currently being used in EAB aircraft. On Thu, Oct 9, 2014 at 6:48 AM, Ralph Finch wrote: > I'm a bit puzzled as to why we, the E/AB community, would seriously > consider Lithium batteries for the main battery. To save weight or space? > The savings are insignificant and the unknowns and risks are not > insignificant. Lithium chemistry makes sense for highly portable > electronics (laptops, tablets, phones) but not so much for us. > > Sure, we DO build and fly *experimental* aircraft, but there's a limit to > how much experimenting most will do. The more proven non-flooded Lead-based > batteries are very safe and convenient and I use them on both my > certificated Aircoupe and the RV-9A that will hopefully be flying next year. > > Ralph Finch > > On Thu, Oct 9, 2014 at 6:48 AM, Robert L. Nuckolls, III < > nuckolls.bob@aeroelectric.com> wrote: > >> At 22:17 2014-10-06, you wrote: >> >> >> There is an article by Dean Sigler in the November 2014 issue of >> KitPlanes Magazine discussing lithium batteries. There is a picture of >> lithium batteries being charged inside of a fireplace. Should aircraft >> lithium battery boxes be made of firebrick? :) >> >> >> Had a great vacation trip punctuated by broken >> airplanes and overnight stays in travel at both >> ends . . . what are the odds? >> >> Got a look at the article cited. This is pretty >> much an academic assemblage of published facts >> about the various lithium products being studied >> and tried in MOTIVE POWER applications where >> energy density and charge/discharge protocols are >> much more demanding. The article is probably >> accurate but minimally relevant to what we're >> doing . . . or proposing to do with lithium battery >> products. >> >> Getting a lithium battery to burn is like any >> other catastrophic energy release in that it >> takes a combination of stacked conditions. In >> the case of an ENGINE CRANKING / STANDBY POWER >> battery, the first condition we'll strive to >> minimize is the choice of chemistries. >> >> My preliminary findings working with the 26650 >> liFe cells purchased off eBay suggest that their >> ratings, and coincidentally their in-service >> risks for abuse, are strongly influenced by the >> boundaries on charge/recharge limits. Many articles >> I've read suggest that optimum battery life is >> achieved if the cells are cycled between about >> 80 and 20 percent of their chemical energy limits. >> The hybrid vehicles program their battery management >> systems to keep routine cycling of the cell packs >> within these or similar limits thus accepting >> a designed-in de-rating of battery capacity. >> >> This de-rating along with choice of a chemistry >> with the most robust resistance to conflagration >> suggest that fire-brick battery boxes are probably >> overkill. Lowered risks for LiFe fire not-withstanding, >> the lithium products finding their way onto TC >> aircraft ARE being housed in enclosures that >> ASSUME a potential for the worst . . . said >> enclosures are designed to contain a battery >> fire and vent products of combustion overboard. >> >> Know too that these offerings have a significant >> proportion of procurement expense tied up in the >> battery management system electronics! >> >> >> [image: Emacs!] >> >> http://tinyurl.com/l6xbev7 >> >> As of this date, I'me aware of no similar >> prophylactics against catastrophic failure being >> offered to the OBAM aviation community. >> >> My cursory studies of the lithium question have produced >> some enlightenment and mild surprises . . . but the >> data gathering methodology was too coarse . . . it seems >> that differences as small as 0.1 volts per cell in charging >> voltage can have a large effect on energy stored. I've >> go more cells ordered and I'm assembling better data >> gathering tools. >> >> One thing I can offer at this stage of the study is >> to strongly object to any marketing of a lithium product >> with words that speak to "lead-acid equivalency" . . . >> these are an entirely different breed of cat and to >> suggest that an end user can expect performance and >> maintenance issues to be a matter of drop-in equivalency >> is at best disingenuous and at worst a tad fraudulent. >> >> To the snow-mobiler or biker who's interests are largely >> limited to engine cranking and service life, the loose >> application of words like 'equivalency' is not terribly >> egregious. Airplanes are be VERY different in operational >> expectations, system integration and failure modes management. >> >> In the mean time, know that the article cited in the >> subject line of this tread has little significance to >> the issues we're wrestling with here on the List. >> >> Watch this space . . . >> >> >> Bob . . . >> > > ________________________________ Message 7 _____________________________________ Time: 09:39:19 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Should a tripped circuit breaker be reset in flight? At 10:07 2014-10-09, you wrote: > >There is an article in the October 2014 issue of Sport Aviation on >page 92 titled, "I'll Never Do That Again". The author experienced >an avionics failure while in IFR conditions. Other pilots in >similar emergency situations have crashed. This pilot was very >experienced. After briefly losing control, he was able to use >backup instruments and land. While safely on the ground, he noticed >a popped circuit breaker and reset it. It immediately tripped >again, accompanied by an unusual smell. The pilot wrote, "I will >never reset a breaker in the air. I did not have a fire, but I >clearly was cooking something while I was on the ramp. Flames on >the ground are a problem. Flames in the air are deadly." > Take away the resettable feature of circuit breakers and they > have no advantage (in most cases) over fuses, other than the cool > factor of the appearance of a neat row of breakers. Fuses cost > less, weigh less, and never fail to open when overloaded. In the revenue generating class of aircraft there can be maintenance conveniences for having disconnect capabilities at the bus . . . I won't pretend to know the big picture of what constitutes an elegant solution for those folks. Further, there is probably not much risk of fire for having reset a breaker . . . even multiple times. The pundits are fond of citing the Ricky Nelson DC-3 crash on New Year's eve 1985 wherein it was hypothesized that repeated attempts to get a gas-fired cabin heater to stay on line were unsuccessful and MAY have lead to the fire which definitely started in the rear of the cabin. Forensics failed to conclusively tag the heater. It's REALLY hard to set anything on fire by repeatedly reseting a breaker as long as the trip is protecting a hard-faulted wire. The major risks for in-flight fire are from failures within a piece of equipment and SOFT faults to a wire. "SOFT" being defined as a condition that dissipates a lot of energy over a period of time but at current levels lower than the trip value for the breaker. Cases in point: Swissair 111 and a C90 that experienced elevator disconnect due to soft-fault arcing of the cable against a wire that was breaker protected at 40A. My own preference for not re-setting breakers has more to do with builder competence in crafting and pilot competence in carry out a Plan-B. These are exercises in pre-incident planning that go to making breaker resets or fuse replacements irrelevant. This isn't about fires, it's about avoiding that deer-in-the-headlights look that overcomes too many of our span-can driving brothers. Incidents described in detail over decades of what I've called the "Dark n Stormy Night" stories popular with the journals . . . Sport Aviation not withstanding. Bob . . . ________________________________ Message 8 _____________________________________ Time: 10:36:04 AM PST US Subject: AeroElectric-List: Re: Should a tripped circuit breaker be reset in flight? From: "rv8builder" In my former life as an airline pilot, the policy on reseting CB's in flight was "If it is absolutely needed for flight (gear, etc), one reset was allowed. If it was not needed for flight (galley, cabin lights, cabin entertainment, etc) no reset in flight was allowed. Dale -------- Dale Read this topic online here: http://forums.matronics.com/viewtopic.php?p=431693#431693 ________________________________ Message 9 _____________________________________ Time: 01:40:13 PM PST US Subject: AeroElectric-List: Re: Should a tripped circuit breaker be reset in flight? From: "stearman456" rv8builder wrote: > In my former life as an airline pilot, the policy on reseting CB's in flight was "If it is absolutely needed for flight (gear, etc), one reset was allowed. If it was not needed for flight (galley, cabin lights, cabin entertainment, etc) no reset in flight was allowed. > > Dale That pretty much covers my current airline's philosophy: "At the discretion of the captain ONE (1) reset is allowed, except for anything involving fuel" (gauge, pump, etc). For a fuel related item there is no reset - it becomes a problem for the maintenance guys at the next landing. And if it's something not required for the safe completion of the flight then we just live with it being u/s. Dan Read this topic online here: http://forums.matronics.com/viewtopic.php?p=431703#431703 ________________________________ Message 10 ____________________________________ Time: 03:01:49 PM PST US From: Ken Ryan Subject: AeroElectric-List: are twisted pairs necessary for RS-232? Dynon Skyview uses RS-232 serial communication. Is twisted wire a requirement for RS-232? The installation manual makes no mention, other than for their "Skyview Network" which is separate from the RS-232 found in the harness. ________________________________ Message 11 ____________________________________ Time: 04:13:42 PM PST US From: Henry Hallam Subject: Re: AeroElectric-List: are twisted pairs necessary for RS-232? Twisted pairs for RS-232 won't accomplish much. If you twist RX and TX together you'll be actively hurting the signal. It's a single-ended signal and can't take advantage of the common-mode rejection provided by a twisted pair. If you have signal integrity problems with it (and can't use the differential equivalent RS-422) then shielded cable is probably the way to go. Henry On Thu, Oct 9, 2014 at 3:00 PM, Ken Ryan wrote: > Dynon Skyview uses RS-232 serial communication. Is twisted wire a > requirement for RS-232? The installation manual makes no mention, other than > for their "Skyview Network" which is separate from the RS-232 found in the > harness. > > ________________________________ Message 12 ____________________________________ Time: 04:32:52 PM PST US From: Ken Ryan Subject: Re: AeroElectric-List: are twisted pairs necessary for RS-232? Thanks Henry. My next question was whether or not it would be acceptable to splice the RS-232 wires. Specifically I would like to connect them to one side of a terminal strip, and then resume them from the other side. It sounds like that should not cause any problem? On Thu, Oct 9, 2014 at 3:12 PM, Henry Hallam wrote: > henry@pericynthion.org> > > Twisted pairs for RS-232 won't accomplish much. If you twist RX and > TX together you'll be actively hurting the signal. It's a > single-ended signal and can't take advantage of the common-mode > rejection provided by a twisted pair. > If you have signal integrity problems with it (and can't use the > differential equivalent RS-422) then shielded cable is probably the > way to go. > > Henry > > On Thu, Oct 9, 2014 at 3:00 PM, Ken Ryan wrote: > > Dynon Skyview uses RS-232 serial communication. Is twisted wire a > > requirement for RS-232? The installation manual makes no mention, other > than > > for their "Skyview Network" which is separate from the RS-232 found in > the > > harness. > > > > > > ________________________________ Message 13 ____________________________________ Time: 05:01:15 PM PST US From: Henry Hallam Subject: Re: AeroElectric-List: are twisted pairs necessary for RS-232? On Thu, Oct 9, 2014 at 4:31 PM, Ken Ryan wrote: > Thanks Henry. My next question was whether or not it would be acceptable to > splice the RS-232 wires. Specifically I would like to connect them to one > side of a terminal strip, and then resume them from the other side. It > sounds like that should not cause any problem? Yes that should be fine. ------------------------------------------------------------------------------------- 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.