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
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| Subject: | Re: battery misconceptions |
At 08:18 PM 9/15/2016, you wrote:
>AeroElectric-List message posted by: Lyle Peterson <lyleap@centurylink.net>
>
>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
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| Subject: | 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
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| Subject: | Re: PC680 Failure Analysis |
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
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| Subject: | Re: 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
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| Subject: | Re: 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
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| Subject: | 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 <rdu.hari@gmail.com>
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
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| Subject: | 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
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| Subject: | Re: VOR/LOC/GS BALUN Fabrication |
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
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