---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Wed 12/24/08: 9 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 01:39 AM - Re: Re: Li-Ion Batteries for aircraft (Robert L. Nuckolls, III) 2. 05:57 AM - Re: Re: Li-Ion Batteries for aircraft (Ernest Christley) 3. 06:33 AM - Re: Re: Li-Ion Batteries for aircraft (Charlie England) 4. 09:35 AM - Re: Anyone done Bob Nuckoll's CBA modifications? (Robert L. Nuckolls, III) 5. 10:01 AM - Re: Re: Li-Ion Batteries for aircraft (Terry Watson) 6. 11:32 AM - Re: Re: Li-Ion Batteries for aircraft (Christopher Barber) 7. 12:24 PM - Re: Re: Li-Ion Batteries for aircraft (Robert L. Nuckolls, III) 8. 09:33 PM - Re: Anyone done Bob Nuckoll's CBA modifications? (CamLight) 9. 11:36 PM - Re: Re: Li-Ion Batteries for aircraft (Dave Leikam) ________________________________ Message 1 _____________________________________ Time: 01:39:09 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Li-Ion Batteries for aircraft At 09:02 AM 12/23/2008, you wrote: > > >Robert L. Nuckolls, III wrote: >> >> A friend of mine made this anecdotal observation about >> batteries in the numerous crashes he investigated: He >> said that if the airplane didn't burn after impact, more >> often than not, the battery was pitched out and could >> be found in the weeds. If the airplane did burn, more >> often than not, the battery was still in the airplane. > >We're way off topic right now, but...huh? How so? The discussion was about the extra-ordinary capabilities of Li-Ion batteries that make their acceptance into aircraft problematic. While their energy/weight ratios and exceedingly low source impedance make them electrically attractive, they're also famous throughout the family of Li-Ion products for spectacular and unpleasant failure modes from within. Even after these batteries are blessed by those who know-more-about-airplanes-than-we-do, there are still considerations for system integration which includes crash safety. >Are you saying that retaining the battery increases the chances of a fire? Doesn't that stand to reason? Fires need ignition sources and aluminum is not hard-sparking material. Hot engines are not even particularly strong ignition sources . . . but a battery capable of thousands of amps of fault current could probably be demonstrated to light off magnesium castings under the right conditions. Lighting off fuel spills is easy. > The takeaway being that the battery isn't our friend during/after > an accident? Would you not share that conclusion with me? Except for the chance that you might sit in the wreck and use the battery to power your radios for the purpose of calling for help, of what practical value is it? Once the airframe is compromised to the extent that the battery is subject to high current discharges, it's easy to assume that fuel tanks are equally compromised. All things considered, if I were on short-final to the rocks, being able to eject the battery is not an unattractive idea. Bob . . . ----------------------------------------) ( . . . a long habit of not thinking ) ( a thing wrong, gives it a superficial ) ( appearance of being right . . . ) ( ) ( -Thomas Paine 1776- ) ---------------------------------------- ________________________________ Message 2 _____________________________________ Time: 05:57:51 AM PST US From: Ernest Christley Subject: Re: AeroElectric-List: Re: Li-Ion Batteries for aircraft Robert L. Nuckolls, III wrote: > The takeaway being that the battery isn't our friend during/after an > accident? > > Would you not share that conclusion with me? Except for > the chance that you might sit in the wreck and use the > battery to power your radios for the purpose of calling > for help, of what practical value is it? Once the airframe > is compromised to the extent that the battery is subject to > high current discharges, it's easy to assume that fuel > tanks are equally compromised. All things considered, if > I were on short-final to the rocks, being able to eject > the battery is not an unattractive idea. > Oh, I agree. It is just not something I've ever heard discussed, or even considered. Now I'm wondering if there are any designs that provide for an battery eject? Considering the logic behind your statement, the the crash investigator you referred to earlier, why aren't there more? ________________________________ Message 3 _____________________________________ Time: 06:33:37 AM PST US From: Charlie England Subject: Re: AeroElectric-List: Re: Li-Ion Batteries for aircraft Robert L. Nuckolls, III wrote: > > > At 09:02 AM 12/23/2008, you wrote: >> >> >> Robert L. Nuckolls, III wrote: >>> >>> A friend of mine made this anecdotal observation about >>> batteries in the numerous crashes he investigated: He >>> said that if the airplane didn't burn after impact, more >>> often than not, the battery was pitched out and could >>> be found in the weeds. If the airplane did burn, more >>> often than not, the battery was still in the airplane. >> >> We're way off topic right now, but...huh? > > How so? The discussion was about the extra-ordinary > capabilities of Li-Ion batteries that make their > acceptance into aircraft problematic. While their > energy/weight ratios and exceedingly low source > impedance make them electrically attractive, they're > also famous throughout the family of Li-Ion products > for spectacular and unpleasant failure modes from > within. > > Even after these batteries are blessed by those who > know-more-about-airplanes-than-we-do, there are still > considerations for system integration which includes > crash safety. > >> Are you saying that retaining the battery increases the chances of a >> fire? > > Doesn't that stand to reason? Fires need ignition sources > and aluminum is not hard-sparking material. Hot engines are > not even particularly strong ignition sources . . . but > a battery capable of thousands of amps of fault current > could probably be demonstrated to light off magnesium castings > under the right conditions. Lighting off fuel spills is > easy. > >> The takeaway being that the battery isn't our friend during/after >> an accident? > > Would you not share that conclusion with me? Except for > the chance that you might sit in the wreck and use the > battery to power your radios for the purpose of calling > for help, of what practical value is it? Once the airframe > is compromised to the extent that the battery is subject to > high current discharges, it's easy to assume that fuel > tanks are equally compromised. All things considered, if > I were on short-final to the rocks, being able to eject > the battery is not an unattractive idea. > > > Bob . . . The 1st thing I thought about when reading the 'pitched battery=no fire' story is, wouldn't it be fairly simple to design a G-activated disconnect mounted directly to the battery? Basically the inverse of an ELT activator, to fail off instead of fail on. Something as simple as a spring- or mechanical fuse-loaded pivoting base for the battery that would allow the top to move forward, and bolt-on bullet or blade style connectors for the battery terminals that would face aft. With spring loaded insulators that would close if the connector halves separate, and the wires behind the battery and locked to structure, most any crash impact should try to move the battery forward, 'pulling the plugs' & allowing the insulators to close. This wouldn't be the simplest project for a homebuilder, but should be relatively easy for an R&D department. Also, having been in a car wreck where the battery moved against the frame & was burning through the steel, there might even be an opportunity to make some money if it's marketed to auto regulators (never get it adopted voluntarily, of course). Charlie ________________________________ Message 4 _____________________________________ Time: 09:35:14 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Anyone done Bob Nuckoll's CBA modifications? At 10:35 PM 12/23/2008, you wrote: >I have used the West Mountain unit a few times. No worries. I >didn't know there was a mod. I bought mine about a year ago and >have used it with an 11 ah battery and a few other smaller ones. I >am getting ready to try it out with my new Oddessy 625. Maybe in a >week, after the holiday. I have loaded the Ver 2 software, but have >not tried it out. > >Sam Hoskins >Murphysboro, IL >www.samhoskins.blogspot.com > > >On Tue, Dec 23, 2008 at 9:53 PM, CamLight ><jmuchow@camlight.com> wrote: ><jmuchow@camlight.com> > >Hello all, >After seeing a few units burn out unexpectedly (including one of >mine), I've been doing an analysis of the West Mountain Radio CBA >II. I was wondering if anyone here had done the MOSFET switch (from >IRL2910 to IRFP2907) detailed in Bob Nuckoll's 4/10/05 analysis of >the CBA II? Thanks! I own 2 of these devices. The first was damaged when I tried to do a 4a discharge on a 24v battery (well within the rated 100W power handling capability of the CBA II). After a determination that the active power load transistor had shorted, I jury-rigged a pair of FAT transistors onto an external heat sink and secured enough functionality to complete the task at hand. It was not intended to be a modification to upgrade the device. I subsequently purchased a second unit and I've been using both for a several years. I had some discussions with the head-shed at West Mountain Radio about the marginal design as demonstrated by my experience. The fellow seemed to believe I was the only one who was having any sort of problem and offered to repair mine under warranty. I'd chopped and hacked it so didn't feel like I was worthy of a warranty action. I ultimately replace the jury-rigged "fix" with a slightly more robust FET in the TO220 package. Both of my cap-meters have performed as advertised since on 12v or smaller batteries. I'm having trouble recalling how my "mod" got loose in the wild. I don't recall posting it to my website but I may have shared a picture and text with someone who has passed it along. Over the years, I've had several inquiries about my "mod" wherein I was unable to back-track the information trail. Suffice it to say that the CBA-II performs well and as advertised on 12-volt and smaller batteries and may well work on most batteries of higher voltage. It's my opinion that the TO-200 case power FET used as a load resistor is marginally applied to this product. If I were building a similar product, it would be more robust in this regard. Bob . . . ----------------------------------------) ( . . . a long habit of not thinking ) ( a thing wrong, gives it a superficial ) ( appearance of being right . . . ) ( ) ( -Thomas Paine 1776- ) ---------------------------------------- ________________________________ Message 5 _____________________________________ Time: 10:01:22 AM PST US From: "Terry Watson" Subject: RE: AeroElectric-List: Re: Li-Ion Batteries for aircraft This is an interesting idea. It should be pretty simple in concept to design an on-impact disconnect for a rear-mounted battery in an RV. Just allow the battery to slide forward a few inches on impact, out of the slotted terminal connectors mounted rigid enough to not follow the battery. RV wings have an optional slotted mount at the leading edge to fuselage connection to allow the wings to shear off. Someone smarter than me could probably come up with a scheme for a firewall mounted (forward of the firewall) battery too. The battery would still be in the airplane, but not connected to any of the wiring. Terry Stalled RV-8A project (too many bright ideas; not enough consistent effort) Seattle -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Ernest Christley Sent: Wednesday, December 24, 2008 5:56 AM Subject: Re: AeroElectric-List: Re: Li-Ion Batteries for aircraft Robert L. Nuckolls, III wrote: > The takeaway being that the battery isn't our friend during/after an > accident? > > Would you not share that conclusion with me? Except for > the chance that you might sit in the wreck and use the > battery to power your radios for the purpose of calling > for help, of what practical value is it? Once the airframe > is compromised to the extent that the battery is subject to > high current discharges, it's easy to assume that fuel > tanks are equally compromised. All things considered, if > I were on short-final to the rocks, being able to eject > the battery is not an unattractive idea. > Oh, I agree. It is just not something I've ever heard discussed, or even considered. Now I'm wondering if there are any designs that provide for an battery eject? Considering the logic behind your statement, the the crash investigator you referred to earlier, why aren't there more? ________________________________ Message 6 _____________________________________ Time: 11:32:54 AM PST US From: "Christopher Barber" Subject: Re: AeroElectric-List: Re: Li-Ion Batteries for aircraft Ok, not a productive comment, however, this discussion has me playing with the thought of hearing: "Captain Picard, the matter/anti-matter containment is failing causing a reaction ark, she is about to blow!" "Geordie, eject the core....NOW!" Yeah, I am more of a NexGen guy then TOS. To show what a geek I can be, the "N" number on my Velocity is N17010. Other Trek geeks will understand that. Merry Christmas all. All the best, Chris Barber Houston ----- Original Message ----- From: "Terry Watson" Sent: Wednesday, December 24, 2008 11:58 AM Subject: RE: AeroElectric-List: Re: Li-Ion Batteries for aircraft > > > This is an interesting idea. It should be pretty simple in concept to > design > an on-impact disconnect for a rear-mounted battery in an RV. Just allow > the > battery to slide forward a few inches on impact, out of the slotted > terminal > connectors mounted rigid enough to not follow the battery. RV wings have > an > optional slotted mount at the leading edge to fuselage connection to allow > the wings to shear off. Someone smarter than me could probably come up > with > a scheme for a firewall mounted (forward of the firewall) battery too. The > battery would still be in the airplane, but not connected to any of the > wiring. > > Terry > Stalled RV-8A project (too many bright ideas; not enough consistent > effort) > Seattle > > -----Original Message----- > From: owner-aeroelectric-list-server@matronics.com > [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Ernest > Christley > Sent: Wednesday, December 24, 2008 5:56 AM > To: aeroelectric-list@matronics.com > Subject: Re: AeroElectric-List: Re: Li-Ion Batteries for aircraft > > > > Robert L. Nuckolls, III wrote: >> The takeaway being that the battery isn't our friend during/after an >> accident? >> >> Would you not share that conclusion with me? Except for >> the chance that you might sit in the wreck and use the >> battery to power your radios for the purpose of calling >> for help, of what practical value is it? Once the airframe >> is compromised to the extent that the battery is subject to >> high current discharges, it's easy to assume that fuel >> tanks are equally compromised. All things considered, if >> I were on short-final to the rocks, being able to eject >> the battery is not an unattractive idea. >> > Oh, I agree. It is just not something I've ever heard discussed, or > even considered. Now I'm wondering if there are any designs that > provide for an battery eject? Considering the logic behind your > statement, the the crash investigator you referred to earlier, why > aren't there more? > > > ________________________________ Message 7 _____________________________________ Time: 12:24:35 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Li-Ion Batteries for aircraft At 07:55 AM 12/24/2008, you wrote: > > >Robert L. Nuckolls, III wrote: >> The takeaway being that the battery isn't our friend >> during/after an accident? >> >> Would you not share that conclusion with me? Except for >> the chance that you might sit in the wreck and use the >> battery to power your radios for the purpose of calling >> for help, of what practical value is it? Once the airframe >> is compromised to the extent that the battery is subject to >> high current discharges, it's easy to assume that fuel >> tanks are equally compromised. All things considered, if >> I were on short-final to the rocks, being able to eject >> the battery is not an unattractive idea. >Oh, I agree. It is just not something I've ever heard discussed, or >even considered. Now I'm wondering if there are any designs that >provide for an battery eject? Considering the logic behind your >statement, the the crash investigator you referred to earlier, why >aren't there more? When I asked the scattered-pieces/smoking-hole crowd at RAC to search their memories and archives for accidents where an electrical failure figured into the chain of events leading up to damage to aircraft/crew. They couldn't come up with one.(*) At the same time, there were electrical issues that caused tense moments and unplanned completions of flight. Bottom line is that a well considered architecture, plan-A/ plan-B operating plan and reasonable training keeps even severe electrical failures from becoming a bad day in the cockpit. Given that OBAM aircraft are MUCH more forgiving than Barons and Jets, electrical failures in flight are even less risky. I don't think there was much interest in reducing the possibility of battery-induced, post-crash fire given that circumstances surrounding the cases where fire did occur were so severe that no useful difference in outcome would have been gained if the airplane had not caught fire. Bob . . . (*) I've personally worked only two accidents in 30+ years that probably started with an electrical failure. One involved a King Air over the Swiss Alps that disappeared from radar and radio contact . . . BEFORE traversing the peaks. The airplane crashed into said peaks COMING THE OTHER WAY. The prevailing theory was that the avionics master relay failed and took down all the good stuff. The pilot decided to return sometime after crossing the peaks and for some reason, descended too early. The other was loss of both alternators in a piston twin flying in ice. Pilot made successful approach to landing looking out the foul weather window. He lost directional control on the runway resulting in loss of airframe and all souls aboard. ________________________________ Message 8 _____________________________________ Time: 09:33:15 PM PST US Subject: AeroElectric-List: Re: Anyone done Bob Nuckoll's CBA modifications? From: "CamLight" nuckolls.bob(at)aeroelect wrote: > > I own 2 of these devices. The first was damaged > when I tried to do a 4a discharge on a 24v battery > (well within the rated 100W power handling capability > of the CBA II). After a determination that the > active power load transistor had shorted, I jury-rigged > a pair of FAT transistors onto an external heat > sink and secured enough functionality to complete the > task at hand. It was not intended to be a modification > to upgrade the device. I subsequently purchased a > second unit and I've been using both for a several > years. > > I had some discussions with the head-shed at > West Mountain Radio about the marginal design > as demonstrated by my experience. The fellow seemed > to believe I was the only one who was having any > sort of problem and offered to repair mine under > warranty. I'd chopped and hacked it so didn't feel > like I was worthy of a warranty action. I ultimately > replace the jury-rigged "fix" with a slightly > more robust FET in the TO220 package. Both of my > cap-meters have performed as advertised since > on 12v or smaller batteries. That's good news! I've heard of about 8 units that have blown their FETs and couple that also took out the driving op-amp and some resistor/capacitors too. I ended up using an Infineon IPP048N06L MOSFET for its great continuous rating for use as a load (DC plot line in the SOA graph). Seems that it's both the higher wattages and higher voltage batteries that can cause problems. Makes sense though. The first is due to temperature and the second due to hotspotting and thermal runaway. nuckolls.bob(at)aeroelect wrote: > > I'm having trouble recalling how my "mod" got > loose in the wild. I don't recall posting it to > my website but I may have shared a picture and > text with someone who has passed it along. Over > the years, I've had several inquiries about my > "mod" wherein I was unable to back-track the > information trail. Well, I can give you the trail I followed. :-) A friend had told me about seeing an analysis of the CBA but forgot where. A Goodle search led to an archive of a thread here on, IIRC, April 10, 2005. In that thread you provided a link to your analysis in the Articles section of your site. But the document was no longer there. This link though gave me the file name and my search led to an individual who had the document available from their site. I don't remember who. nuckolls.bob(at)aeroelect wrote: > > Suffice it to say that the CBA-II performs well > and as advertised on 12-volt and smaller batteries > and may well work on most batteries of higher voltage. > It's my opinion that the TO-200 case power FET used > as a load resistor is marginally applied to this > product. If I were building a similar product, > it would be more robust in this regard. > > Bob . . . > I completely agree. My analysis of two CBA's was pretty extensive (43 page document) and led me to conclude that it shouldn't be used at over 65W for long-term reliability and 86W to prevent the MOSFET from exceeding its max rated operating temperature. I also found out that the CBA's stock MOSFET isn't even rated for use as a load and was susceptible to hotspotting and thermal runaway (resulting in the MOSFET burning out) at well below the CBA's 100W rating when discharging at higher voltages. A MOSFET change, over to the IPP048N06L, and a fan change were the mods I made to bring the CBA's continuous power rating up to 106W at up to 48V without worrying about exceeding any of the MOSFET's specs. The extra fan also helped to keep the fuse and fuseholders from dropping out of the circuit board too when discharging at 30A or so. It happened more than once to me (and others) before we finally found ways to cool the circuit board and fuse. Very frustrating. :) -------- John M. Owner CamLight Systems Read this topic online here: http://forums.matronics.com/viewtopic.php?p=221015#221015 ________________________________ Message 9 _____________________________________ Time: 11:36:39 PM PST US From: "Dave Leikam" Subject: Re: AeroElectric-List: Re: Li-Ion Batteries for aircraft I would consider a dual wire high current plug similar to one used on my snowplow main power lead. The plug supplies current to a motor similar to an engine starting motor which drives hydraulics to operate the plow. The plug is very robust and under very harsh operating conditions has never unplugged itself during plowing operations. The plug hangs freely between the front bumper of my truck and the plow. However, with a good tug the plug separates to disconnect the wires to remove the plow unit from my truck. This could be installed in the battery connection wires of the airplane and supported so as to disconnect in the event of excessive forward g forces. The contact pins are also recessed in plastic so after disconnect, there would be no chance of contact with other metal if the battery terminals were also covered. See 4b and 4c in the link below. http://www.rustrepair.com/snow_plow_parts/onlinecat.htm?r=ds&p=sn-boss-bs.elec Dave Leikam RV-10 #40496 N89DA (Reserved) Muskego, WI ----- Original Message ----- From: "Terry Watson" Sent: Wednesday, December 24, 2008 11:58 AM Subject: RE: AeroElectric-List: Re: Li-Ion Batteries for aircraft > > > This is an interesting idea. It should be pretty simple in concept to > design > an on-impact disconnect for a rear-mounted battery in an RV. Just allow > the > battery to slide forward a few inches on impact, out of the slotted > terminal > connectors mounted rigid enough to not follow the battery. RV wings have > an > optional slotted mount at the leading edge to fuselage connection to allow > the wings to shear off. Someone smarter than me could probably come up > with > a scheme for a firewall mounted (forward of the firewall) battery too. The > battery would still be in the airplane, but not connected to any of the > wiring. > > Terry > Stalled RV-8A project (too many bright ideas; not enough consistent > effort) > Seattle > > -----Original Message----- > From: owner-aeroelectric-list-server@matronics.com > [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Ernest > Christley > Sent: Wednesday, December 24, 2008 5:56 AM > To: aeroelectric-list@matronics.com > Subject: Re: AeroElectric-List: Re: Li-Ion Batteries for aircraft > > > > Robert L. Nuckolls, III wrote: >> The takeaway being that the battery isn't our friend during/after an >> accident? >> >> Would you not share that conclusion with me? Except for >> the chance that you might sit in the wreck and use the >> battery to power your radios for the purpose of calling >> for help, of what practical value is it? Once the airframe >> is compromised to the extent that the battery is subject to >> high current discharges, it's easy to assume that fuel >> tanks are equally compromised. All things considered, if >> I were on short-final to the rocks, being able to eject >> the battery is not an unattractive idea. >> > Oh, I agree. It is just not something I've ever heard discussed, or > even considered. Now I'm wondering if there are any designs that > provide for an battery eject? Considering the logic behind your > statement, the the crash investigator you referred to earlier, why > aren't there more? > > > ------------------------------------------------------------------------------------- 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.