---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Fri 09/16/16: 8 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 07:36 AM - Re: battery misconceptions (Robert L. Nuckolls, III) 2. 09:21 AM - PC680 Failure Analysis (Robert L. Nuckolls, III) 3. 11:20 AM - Re: PC680 Failure Analysis (user9253) 4. 11:40 AM - Re: PC680 Failure Analysis (Ken Ryan) 5. 01:06 PM - Re: PC680 Failure Analysis (Robert L. Nuckolls, III) 6. 05:38 PM - Re: VOR/LOC/GS BALUN Fabrication (Hariharan Gopalan) 7. 05:38 PM - VOR/LOC/GS BALUN Fabrication (Hariharan Gopalan) 8. 07:19 PM - Re: VOR/LOC/GS BALUN Fabrication (user9253) ________________________________ Message 1 _____________________________________ Time: 07:36:41 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: battery misconceptions At 08:18 PM 9/15/2016, you wrote: >AeroElectric-List message posted by: Lyle Peterson > >A couple on interesting concepts are revealed there. Theoretically >the batteries should be identical in all the factors mentioned. In >reality, I doubt you will find that situation in the wild. There >may be two that are close enough for government work but not identical > >Why the need or desire for batteries in parallel? The output >voltage is not increased. The capacity is increased but a better >plan would be one battery of sufficient capacity for the task at hand. Paralleled batteries have been proposed in numerous AEC architectures over the years . . . but paralleled only for the purpose of (1) improved cranking performance (Z-14) or (2) offering a means for separating two batteries into separate tasks during battery-only endurance operations. In these cased, the batteries were only CHARGED in parallel . . . a situation were differences in size and condition of the battery is transparent to functionality of all batteries. During battery-only ops, individual batteries are partitioned into separate tasks. Again, the capacity and condition of any one battery has no influence on performance of other battery(ies). >If higher voltage is needed, but by using two batteries in series, >the same concept the writer mentions should be applied or use one >higher voltage battery. Even then you have a series of batteries, >or cells, in series each operating on its own. This is what happens when a battery is crafted to meet system design goals. Earliest cars were 6v (3 lead-acid cells in battery). Later cars were 12v (6 cells), some vehicles are 24v (12 cells), many electric vehicles are 36v (18 cells). Now, wether that array of cells is crafted in one device of necessary cells or multiple devices with smaller numbers of cells in series is driven by design goals. >Regular cell checks would help to reduce differences in the cells >thus the performance of the whole battery package. Exactly. Cells connected series are no more capable than the weakest cell in the string. Back in the days when I shot a lot of film professionally, I used Vivitar 283 flashguns with 4xAA battery paks. I tried using NiCd . . . for a time . . . but they proved labor intensive to mitigate risk of a poor shoot. If only one cell of the 4 was weak, it would fall out of bed before the other three cells . . . but the whole array became useless. For a time, I would check the cells for capacity and build 'teams' of cells with similar capacity but it took too much time. Clients were paying all expenses of the job and a hand-full of batteries for radios, cameras, telemetry and data acquisition systems was perhaps 0.1% of the mission costs. I quit fiddling with NiCd and loaded fresh alkaline cells into all electro-whizzies at the start of the day. Cell matching becomes important for the case of building a large array battery from a series connected array of smaller batteries, . . . not just within any one battery but the whole string. This is the condition that prompts cap checks with benchmarks that call for replacement of the whole array at some established value . . . usually 80% of new. This benchmark is picked to meet battery only endurance goals while insuring that no single cell gets so far ahead in the down-hill run to failure that it puts all other cells at risk. Bob . . . ________________________________ Message 2 _____________________________________ Time: 09:21:52 AM PST US From: "Robert L. Nuckolls, III" Subject: AeroElectric-List: PC680 Failure Analysis A few weeks ago I received a PC680 battery from Joe Gores that was presenting intermittent behaviors. Seems the battery would 'go open' but perhaps with some external coaxing, prodding, banging, etc . . . it would come alive. Got a chance to get on the mill in Wichita last week and we carved the top off the failed battery for inspection. The battery's as-received condition is illustrated at http://tinyurl.com/zkp45md There was no evidence of external damage or internal distress. Terminal voltage as received was zero. I tried some external forces suggested by Joe to no avail. Tear-down images are posted at http://tinyurl.com/hspd7kt A 4-wire ohmmeter was used to check inter-cell connections http://tinyurl.com/z5wauwc. All execpt the leftmost interconnect presented sub-milliohm continuity. The leftmost joint was open circuit. Prying this joint open . . . http://tinyurl.com/hcmns8t . . . revealed a weld fracture wherein the entire face of the weld exhibits corrosion; there was no evidence of a metallic bridge across the joint prior to opening it up. It appears this failure was a long time in the making. Bob . . . ________________________________ Message 3 _____________________________________ Time: 11:20:40 AM PST US Subject: AeroElectric-List: Re: PC680 Failure Analysis From: "user9253" Bob, I am happy that you found a problem and it was not my imagination. If that broken weld were repaired, I'm sure the battery would crank an engine just fine. The battery was new in 2010. (The sticker with 2016 on it is not the date.) I have not been reimbursed for the postage yet. The post office clerk said that using a flat-rate box saved half the cost of sending in a plain cardboard box. The lesson to be learned from this is that even though a battery failure is highly unlikely, it can happen. The first symptom (low voltage alarm at idle RPM) occurred while flying, even though the engine cranked just fine. -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=460530#460530 ________________________________ Message 4 _____________________________________ Time: 11:40:00 AM PST US From: Ken Ryan Subject: Re: AeroElectric-List: PC680 Failure Analysis I wonder if this battery would have passed the 80% draw down test? On Fri, Sep 16, 2016 at 8:19 AM, Robert L. Nuckolls, III < nuckolls.bob@aeroelectric.com> wrote: > nuckolls.bob@aeroelectric.com> > > A few weeks ago I received a PC680 battery from > Joe Gores that was presenting intermittent behaviors. > Seems the battery would 'go open' but perhaps with some > external coaxing, prodding, banging, etc . . . it would > come alive. > > Got a chance to get on the mill in Wichita last week > and we carved the top off the failed battery for > inspection. > > The battery's as-received condition is illustrated > at http://tinyurl.com/zkp45md > > There was no evidence of external damage or internal > distress. Terminal voltage as received was zero. I tried > some external forces suggested by Joe to no avail. > > Tear-down images are posted at http://tinyurl.com/hspd7kt > > A 4-wire ohmmeter was used to check inter-cell > connections http://tinyurl.com/z5wauwc. All execpt the > leftmost interconnect presented sub-milliohm continuity. > The leftmost joint was open circuit. > > Prying this joint open . . . > > http://tinyurl.com/hcmns8t > > . . . revealed a weld fracture wherein the entire > face of the weld exhibits corrosion; there was > no evidence of a metallic bridge across the joint > prior to opening it up. > > It appears this failure was a long time in the > making. > > > Bob . . . > > ________________________________ Message 5 _____________________________________ Time: 01:06:25 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: PC680 Failure Analysis At 01:35 PM 9/16/2016, you wrote: >I wonder if this battery would have passed the 80% draw down test? Interesting thought. I suppose I could have tested it right after opening it up . . . but its been open to atmosphere for quite awhile. I put a charger on a couple of cells but they've dried out. Bob . . . ________________________________ Message 6 _____________________________________ Time: 05:38:30 PM PST US From: Hariharan Gopalan Subject: AeroElectric-List: Re: VOR/LOC/GS BALUN Fabrication Meant to include the link: http://www.aeroelectric.com/articles/BALUN/Balun_Fabrication.html On Fri, Sep 16, 2016 at 8:35 PM, Hariharan Gopalan wrote: > Hello Group > > I was trying to fabricate this cable, but having trouble in step 2. The > exposed braid refuses to suck up the molten solder. The moment I put a > soldering iron ( a standard radio shack 35W iron) the solder freezes up and > won't melt and flow. Have enough flux applied to the braid, not sure what I > can do to get this tinned. > > any pointers would be highly appreciated > > Thanks > Hari > ________________________________ Message 7 _____________________________________ Time: 05:38:31 PM PST US From: Hariharan Gopalan Subject: AeroElectric-List: VOR/LOC/GS BALUN Fabrication Hello Group I was trying to fabricate this cable, but having trouble in step 2. The exposed braid refuses to suck up the molten solder. The moment I put a soldering iron ( a standard radio shack 35W iron) the solder freezes up and won't melt and flow. Have enough flux applied to the braid, not sure what I can do to get this tinned. any pointers would be highly appreciated Thanks Hari ________________________________ Message 8 _____________________________________ Time: 07:19:07 PM PST US Subject: AeroElectric-List: Re: VOR/LOC/GS BALUN Fabrication From: "user9253" What kind of solder are you using? Some types melt at a higher temperature. The wire might not be getting hot enough or made of a metal that does not readily accept solder. What kind of flux are you using? Solder made for electrical connections usually has a flux core and extra flux is not needed. Flux made for plumbing is acid based and will cause electrical connections to corrode and fail eventually. -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=460541#460541 ------------------------------------------------------------------------------------- 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.