Today's Message Index:
----------------------
1. 05:58 AM - Fw: The word from the man... (Steve Stearns)
2. 05:58 AM - Re: Why CB on regulator field supply? (Voyager)
3. 06:18 AM - Re: Battery capacity test (dj_theis)
4. 06:23 AM - Re: Fw: The word from the man... (Paul Fisher)
5. 06:23 AM - Re: Battery capacity test (Robert L. Nuckolls, III)
6. 06:24 AM - Re: Battery capacity test (Robert L. Nuckolls, III)
7. 07:28 AM - Re: Battery capacity test (Paul Fisher)
8. 08:10 AM - Re: Battery capacity test (Robert L. Nuckolls, III)
9. 08:54 AM - Re: Battery capacity test (Charlie England)
10. 02:35 PM - Re: Battery capacity test (Robert L. Nuckolls, III)
Message 1
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| Subject: | Fwd: The word from the man... |
Paul Fisher enquired about temp compensation of battery tests. Here's what
Bob N. supplied a while back when I asked the same thing.
Steve.
---------- Forwarded message ---------
From: Steve Stearns <steve@tomasara.com>
Subject: The word from the man...
Time: 08:44:19 PM PST US
From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
Subject: Re: AeroElectric-List: How to temperature derate AGM capacity?
At 09:17 PM 8/21/2021, you wrote:
>Greetings All,
>
>I build up and I'm using a 3 ohm version of
>Bob's Battery Capacity tester that he designed a
>while back.=C2 So I get nominally a 4 Amp
>discharge which, for a new 17 amp-hr AGM battery
>(whatever brand Batteries Plus is currently
>selling), when new, I get something=C2 like 3:45
>before the output voltage drops below 11 volts
>(where my threshold is set).=C2 And after about 3
>years, it's capacity has dropped about 20% or
>more and I rotate it out (Longeze -> Motorcycle
>-> Taylorcraft -> Telescope -> lab).
>
>However, it's clear the tested capacity varies
>greatly with ambient temperature so I would like
>to normalize my test results, based on
>temperature, so I can get more accurate
>comparisons.=C2 Additionally, I'd also like to
>understand the derating so that I can more
>accurately=C2 estimate my effective no-alternator
>battery endurance given that I often fly up high
>where it can be quite cold where the battery
>resides.=C2 So it's likely quite a bit shorter
>than the time I measure in the lab at the same
>output current.=C2 I Googled around and didn't find any answers.
>
>Does anyone have the capacity derating for cold
>temps on an AGM battery available?
See Figure 5 of https://tinyurl.com/yekn362u
Figure 6 of
https://www.power-sonic.com/wp-content/uploads/2018/12/Technical-Manual.pdf
https://kb.unavco.org/kb/article/sla-battery-cold-performance-tests-gel-vs-
agm-386.html
https://www.dcbattery.com/lifeline_capacity_temp_graph.html
Bob . . .
Message 2
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| Subject: | Re: Why CB on regulator field supply? |
Bob, thanks for your explanation. What you said is what I was guessing, but it
is good to hear it from the source. I plan to use a CB on the alternator and
fuses everywhere else as I think the alternator field is the only circuit where
you consistently use a CB in your architectural diagrams. Please let me know
if there are other areas where you consider a CB a better solution.
Regards,
Matt
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=506007#506007
Message 3
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| Subject: | Re: Battery capacity test |
Good question Paul and I believe the short answer is yes, temperature will affect
battery performance. Its a common expectation that temperature will impact
any chemical reaction rate and battery output is driven by the chemistry of the
battery. The unknown is what the actual relationship (curve) is.
Here is one (unverified) note on battery performance vs. temperature.
https://www.intercel.eu/frequently-asked-questions/temperature-effects-on-batteries/
The actual performance reduction of your battery, as a function temperature, could
be tested by simply repeating your test after warming the battery to room
temperature (which might take a few hours to warm). Something that would be
interesting to know, if you have time.
To Charlies point, the idea is to track your batterys performance change as it
ages. So, a single point of time to 10.5 volts has less value without knowing
what it was when new (and probably at the same test temperature).
Dan
--------
Dan Theis
Scratch building Sonex #1362
Still working on the Revmaster Alternator improvement
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=506009#506009
Message 4
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| Subject: | Re: Fwd: The word from the man... |
My apologies for not searching the archives before I posted a question. I
should have known someone would have asked this question before I did!
Thank you Steve, this is exactly the data I was looking for! And also
thanks to Bob for answering your question in the first place!
Paul
On Sun, Feb 13, 2022, 08:04 Steve Stearns <steve@tomasara.com> wrote:
> Paul Fisher enquired about temp compensation of battery tests. Here's
> what Bob N. supplied a while back when I asked the same thing.
>
> Steve.
>
> ---------- Forwarded message ---------
> From: Steve Stearns <steve@tomasara.com>
> Date: Sun, Oct 24, 2021 at 8:02 PM
> Subject: The word from the man...
> To: Ion Huss / Lisa Doughty <lisnion@yahoo.com>
>
>
> Time: 08:44:19 PM PST US
> From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
> Subject: Re: AeroElectric-List: How to temperature derate AGM capacity?
>
> At 09:17 PM 8/21/2021, you wrote:
> >Greetings All,
> >
> >I build up and I'm using a 3 ohm version of
> >Bob's Battery Capacity tester that he designed a
> >while back.=C2 So I get nominally a 4 Amp
> >discharge which, for a new 17 amp-hr AGM battery
> >(whatever brand Batteries Plus is currently
> >selling), when new, I get something=C2 like 3:45
> >before the output voltage drops below 11 volts
> >(where my threshold is set).=C2 And after about 3
> >years, it's capacity has dropped about 20% or
> >more and I rotate it out (Longeze -> Motorcycle
> >-> Taylorcraft -> Telescope -> lab).
> >
> >However, it's clear the tested capacity varies
> >greatly with ambient temperature so I would like
> >to normalize my test results, based on
> >temperature, so I can get more accurate
> >comparisons.=C2 Additionally, I'd also like to
> >understand the derating so that I can more
> >accurately=C2 estimate my effective no-alternator
> >battery endurance given that I often fly up high
> >where it can be quite cold where the battery
> >resides.=C2 So it's likely quite a bit shorter
> >than the time I measure in the lab at the same
> >output current.=C2 I Googled around and didn't find any answers.
> >
> >Does anyone have the capacity derating for cold
> >temps on an AGM battery available?
>
>
> See Figure 5 of https://tinyurl.com/yekn362u
>
> Figure 6 of
> https://www.power-sonic.com/wp-content/uploads/2018/12/Technical-Manual.pdf
>
>
> https://kb.unavco.org/kb/article/sla-battery-cold-performance-tests-gel-vs-
> agm-386.html
>
>
> https://www.dcbattery.com/lifeline_capacity_temp_graph.html
>
>
> Bob . . .
>
Message 5
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| Subject: | Re: Battery capacity test |
At 06:34 PM 2/12/2022, you wrote:
>I built a battery capacity tester similar to the
>one described in this document:
><http://www.aeroelectric.com/articles/battest.pdf>http://www.aeroelectric.c
om/articles/battest.pdf
>
>I tested my battery down to 10.5 volts and got
>152 minutes on a 16 AH battery.=C2 So I think I'm
>at ~62% of the original capacity.
>
>Now my question - it was 17 degrees Fahrenheit
>(-8C) when I did my test, so do I need to compensate the test for
temperature?
>
>Either way I think it's time for a new
>battery.=C2 I'm just curious about the physics of
>the test when done at colder (or hotter!) than some standard temperature.
>
>Paul Fisher
EXCELLENT question! Accurate evaluation of battery
condition, while not an art, is not a simple
matter of pulling out a dip-stick. As you have
observed, the temperature at which the test was
conducted represents a confounding influence
for comparing observed condition with as-new
condition.
I think I mentioned in the articles describing
this 'po boys capacity meter' as being only
loosely calibrated. However, if one holds
all potentially confounding effects constant,
then the meter does offer a reasonably accurate
COMPARISON of present condition with as-new
condition over a series preventative maintenance
tests.
The best use of this technique calls for testing
your battery when brand new . . . or certainly
within a short time after being placed in service.
Off the shelf batteries will GAIN a small capacity
after a few charge-discharge events. And by 'discharge'
we mean taken down by a significant fraction of
total capacity . . . say 1/3 or so.
Then use the value of the first test
as a benchmark for as-new capacity. Now you
have a number by which you can deduce percent
of remaining capacity with fair accuracy. Of
course, potentially confounding influences
need to be controlled. Do your test after
the battery has been on the bench at room temperature
and supported on a maintainer for 24 hours.
Of course a number with significant value represents
ENDURANCE. This number is easily deduced by
testing in the airplane where you use your
voltage sense device to control the e-bus
relay. Use ship's endurance loads to discharge
the battery. The time interval secured with
this test is a real performance number irrespective
of percent of as-new capacity.
Well . . . sort of. It's still a good thing
to be aware of the percentage of as-new capacity.
You are not well advised to make a replacement
at 60 or 70 percent of new even if that number
meets your endurance requirements. When a battery
has degraded that far, the slope representing
rate of decay is increasing rapidly.
Industry wide convention suggests 80% as a
practical and confident benchmark for replacement.
So that takes us back to bench testing in
controlled conditions with that micky-mouse
cap checker. It will flag the 80% condition
with satisfactory accuracy.
Bob . . .
Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"
Message 6
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| Subject: | Re: Battery capacity test |
At 10:01 PM 2/12/2022, you wrote:
>What was the duration when it was new?
Right ON!
Bob . . .
Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"
Message 7
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| Subject: | Re: Battery capacity test |
Thanks Bob. I thought this was a significant sentence "Do your test after
the battery has been on the bench at room temperature and supported on a
maintainer for 24 hours.". Just testing the battery on the plane in the
non climate controlled hangar doesn't necessarily help.
Still learning.
Paul
On Sun, Feb 13, 2022, 08:27 Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> At 06:34 PM 2/12/2022, you wrote:
>
> I built a battery capacity tester similar to the one described in this
> document:
> http://www.aeroelectric.com/articles/battest.pdf
>
> I tested my battery down to 10.5 volts and got 152 minutes on a 16 AH
> battery.=C3=82 So I think I'm at ~62% of the original capacity.
>
> Now my question - it was 17 degrees Fahrenheit (-8C) when I did my test,
> so do I need to compensate the test for temperature?
>
> Either way I think it's time for a new battery.=C3=82 I'm just curious a
bout
> the physics of the test when done at colder (or hotter!) than some standa
rd
> temperature.
>
> Paul Fisher
>
>
> EXCELLENT question! Accurate evaluation of battery
> condition, while not an art, is not a simple
> matter of pulling out a dip-stick. As you have
> observed, the temperature at which the test was
> conducted represents a confounding influence
> for comparing observed condition with as-new
> condition.
>
> I think I mentioned in the articles describing
> this 'po boys capacity meter' as being only
> loosely calibrated. However, if one holds
> all potentially confounding effects constant,
> then the meter does offer a reasonably accurate
> COMPARISON of present condition with as-new
> condition over a series preventative maintenance
> tests.
>
> The best use of this technique calls for testing
> your battery when brand new . . . or certainly
> within a short time after being placed in service.
> Off the shelf batteries will GAIN a small capacity
> after a few charge-discharge events. And by 'discharge'
> we mean taken down by a significant fraction of
> total capacity . . . say 1/3 or so.
>
> Then use the value of the first test
> as a benchmark for as-new capacity. Now you
> have a number by which you can deduce percent
> of remaining capacity with fair accuracy. Of
> course, potentially confounding influences
> need to be controlled. Do your test after
> the battery has been on the bench at room temperature
> and supported on a maintainer for 24 hours.
>
> Of course a number with significant value represents
> ENDURANCE. This number is easily deduced by
> testing in the airplane where you use your
> voltage sense device to control the e-bus
> relay. Use ship's endurance loads to discharge
> the battery. The time interval secured with
> this test is a real performance number irrespective
> of percent of as-new capacity.
>
> Well . . . sort of. It's still a good thing
> to be aware of the percentage of as-new capacity.
> You are not well advised to make a replacement
> at 60 or 70 percent of new even if that number
> meets your endurance requirements. When a battery
> has degraded that far, the slope representing
> rate of decay is increasing rapidly.
>
> Industry wide convention suggests 80% as a
> practical and confident benchmark for replacement.
> So that takes us back to bench testing in
> controlled conditions with that micky-mouse
> cap checker. It will flag the 80% condition
> with satisfactory accuracy.
>
>
> Bob . . .
>
> Un impeachable logic: George Carlin asked, "If black boxes
> survive crashes, why don't they make the whole airplane
> out of that stuff?"
>
Message 8
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| Subject: | Re: Battery capacity test |
At 09:27 AM 2/13/2022, you wrote:
>Thanks Bob.=C2 I thought this was a significant
>sentence "Do your test after the battery has
>been on the bench at room temperature and
>supported on a maintainer for 24 hours.".=C2 =C2
>Just testing the battery on the plane in the non
>climate controlled hangar doesn't necessarily help.
It would IF you 'standardize' test
conditions for as-new and subsequent tests . . .
Here's one data point for capacity vs. temperature
in lead-acid chemistry.
https://tinyurl.com/ycng8hll
Bob . . .
Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"
Message 9
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| Subject: | Re: Battery capacity test |
On Sun, Feb 13, 2022 at 10:13 AM Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> At 09:27 AM 2/13/2022, you wrote:
>
> Thanks Bob.=C3=82 I thought this was a significant sentence "Do your tes
t
> after the battery has been on the bench at room temperature and supported
> on a maintainer for 24 hours.".=C3=82 =C3=82 Just testing the battery on
the plane
> in the non climate controlled hangar doesn't necessarily help.
>
>
> It would IF you 'standardize' test
> conditions for as-new and subsequent tests . . .
>
> Here's one data point for capacity vs. temperature
> in lead-acid chemistry.
>
> https://tinyurl.com/ycng8hll
>
>
> Bob . . .
>
It would appear, based on that particular chart & converting 17F to -8C,
his capacity is still close to 100%. Looks like pretty close to 62% at that
temperature. (I realize that flooded cell charts might not perfectly
translate to an AGM battery.)
Charlie
Message 10
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| Subject: | Re: Battery capacity test |
>
>
>It would appear, based on that particular chart & converting 17F to
>-8C, his capacity is still close to 100%. Looks like pretty close to
>62% at that temperature. (I realize that flooded cell charts might
>not perfectly translate to an AGM battery.)
They are similar . . . I cannot disagree. I would
encourage a repeat test at room temperature.
Bob . . .
Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"
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