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nuckolls.bob(at)cox.net Guest
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Posted: Sat Oct 04, 2008 2:49 pm Post subject: What is the best value battery right now? |
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At 09:30 AM 10/3/2008 -0700, you wrote:
Quote: |
I have an RV-8 with an IO-360 180 hp engine and need to replace the
current battery. I think it is a RG-25XC. In past topics I've seen the
Odessey PC-680 mentioned along with the Powersonic (?) PS-12180, Panasonic
LC-X1220P and a LC-RD1217P.
Is there a current favorite that can be found for a reasonable price? If
so, please post name, model, and a good source.
Thanks,
John
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How do you quantify "value"? Lacking data beyond statements
like "My brand Z battery has been in the airplane 5 years
and it still starts my engine" what qualities in a battery
are most important to you. Further, how much $time$ are you
willing to spend to acquire, maintain and monitor that battery
for ability to meet your design goals?
If you're a day vfr airplane, don't care about alternator-out
endurance and will accept a risk of having to hand-prop the engine
or replace a battery off the home field, then anecdotal offerings
of 5-year service life may be useful to you.
On the other hand, if you have a design goal of x.x hours alternator-
out operation of the endurance bus then meeting the design goal
is driven not only by the demonstrated robustness of the battery
but your willingness to do periodic capacity tests to make sure
the design goals are not violated.
Right now, periodic capacity testing involves either running
your e-bus from the battery and seeing how long it takes to
get down to 11.0 volts -or- doing on-purpose capacity measurements
with some device like . .
http://westmountainradio.com/CBA.htm
that will allow you to do a precise evaluation of your
battery's ability to perform.
Here's where you have to make a judgement of value based
on the economics of $time$. You buy a battery for $time$,
buy a piece of test equipment for $time$ and then invest
$time$ at each determination for continued airworthiness
against your design goals. Nobody can advise you as to
the trade offs without knowing your personal quantification
on $time$.
I've often suggested that the highest value batter is that
which meets all design goals with a minimum expenditure
of $time$. Consider that if you buy the least expensive battery
you can find, say . . .
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=522-1014-ND
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=P231-ND
http://www.batteryuniverse.com/Sealed-Lead-Acid/CSB/GH12170/GZ12180NB_CSB_GH12170_Sealed-Lead-Acid
and divide the cost of acquisition by hours flown per year
and simply replace it every annual, you now have a hard data
number for the cost of meeting your design goals.
Periodic replacement of an inexpensive battery eliminates
the $time$ one is tempted to invest in a $high-quality$ battery,
$test-equipment$ and the $time$ to exercise that equipment
until the battery finally shows that it's no longer airworthy.
That's a decision that nobody can make for you. Further,
lacking that detail in a value-study, your choice of product
made from the anecdotal influences here on the List are
not much better than basing it on a television advertisement.
You will find a host of experiences ranging from "that's a
piece of trash" to "best battery since they started slicing
bread". Nobody is lying to you. Maybe nobody is trying to
persuade you. But if you NEED for the battery to perform
to some expectations for alternator-out endurance, none of
this will be useful data for getting the most return on
expenditure of your flying dollars.
Bob . . .
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simon(at)synchronousdesig Guest
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Posted: Mon Oct 06, 2008 12:39 pm Post subject: What is the best value battery right now? |
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