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steve(at)tomasara.com
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 Posted: Sun Feb 13, 2022 5:58 am Post subject: Fwd: The word from the man... |
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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(at)tomasara.com (steve(at)tomasara.com)>
Date: Sun, Oct 24, 2021 at 8:02 PM
Subject: The word from the man...
To: Ion Huss / Lisa Doughty <lisnion(at)yahoo.com (lisnion(at)yahoo.com)>
Time: 08:44:19 PM PST US
From: "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)>
Subject: Re: AeroElectric-List: How to temperature derate AGM capacity?
At 09:17 PM 8/21/2021, you wrote:
| Quote: | 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 . . .
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rv7a.n18pf(at)gmail.com
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| Posted: Sun Feb 13, 2022 6:23 am Post subject: Fwd: The word from the man... |
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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(at)tomasara.com (steve(at)tomasara.com)> wrote:
| Quote: | 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(at)tomasara.com (steve(at)tomasara.com)>
Date: Sun, Oct 24, 2021 at 8:02 PM
Subject: The word from the man...
To: Ion Huss / Lisa Doughty <lisnion(at)yahoo.com (lisnion(at)yahoo.com)>
Time: 08:44:19 PM PST US
From: "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)>
Subject: Re: How to temperature derate AGM capacity?
At 09:17 PM 8/21/2021, you wrote:
| Quote: | 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 . . .
|
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http://www.matronics.com/Navigator?AeroElectric-List |
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