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rhdudley1(at)bellsouth.ne
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 Posted: Thu Mar 01, 2007 10:34 am Post subject: 18 AH Battery Test Data |
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Listers,
FWIW I have been following the procedure of replacing my 18/17.X AH RG
battery annually for the last two years. This year, I decided to do an
endurance test on the "old" battery. Using an automotive two filament
headlamp with the filaments in parallel, I was able to start at a
current of 6.7 amps drain to simulate an endurance buss demand with a
failed alternator. The battery has been used for one year including
about 40 flight hours and 50 engine starts.
The battery is a 17-18 AH sold by Batteries Plus sometimes with the
name Xtreme Plus.
My engine is an O-320 with 110 plus hours on it. These batteries turn
the engine over very "smartly" only observed at temperatures above 60F.
At the beginning of the test, the current was 6.7 A and at the end at
5.6 A . This decline is partly explained by the voltage decline as well
as filament resistance decrease with temperature in the lamp.
These results are consistent with the specification sheet provided for
the Xtreme Plus batteries which predicts a two hour endurance at 6A.
Regards,
Richard Dudley
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nuckollsr(at)cox.net
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| Posted: Sun Mar 04, 2007 4:32 pm Post subject: 18 AH Battery Test Data |
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At 01:28 PM 3/1/2007 -0500, you wrote:
| Quote: | Listers,
FWIW I have been following the procedure of replacing my 18/17.X AH RG
battery annually for the last two years. This year, I decided to do an
endurance test on the "old" battery. Using an automotive two filament
headlamp with the filaments in parallel, I was able to start at a current
of 6.7 amps drain to simulate an endurance buss demand with a failed
alternator. The battery has been used for one year including about 40
flight hours and 50 engine starts.
The battery is a 17-18 AH sold by Batteries Plus sometimes with the name
Xtreme Plus.
My engine is an O-320 with 110 plus hours on it. These batteries turn the
engine over very "smartly" only observed at temperatures above 60F.
At the beginning of the test, the current was 6.7 A and at the end at 5.6
A . This decline is partly explained by the voltage decline as well as
filament resistance decrease with temperature in the lamp.
These results are consistent with the specification sheet provided for the
Xtreme Plus batteries which predicts a two hour endurance at 6A.
Regards,
Richard Dudley
|
Good data sir. Thanks for sharing. Richard's experiment
underscores the idea that MOST RG/VSLA batteries are
capable of providing satisfactory service for periods
of more than a year.
The problem to be cited and solved is what are YOUR
personal requirements for support of electro-whizzies
in the alternator-out, endurance mode? Further, what
is your $time$ and $equipment$ investments worth to
track your battery's performance?
I have a number of batteries in the shop that are used
for various portable power applications . . . some are
over 5 years old. Some are down to less than 80% of original
capacity. However, the equipment needed to check a battery's
present ability is always available as a standard component
of my professional tools. The $time$ for me to put a dipstick
into a battery's capacity takes perhaps two minutes total
time. One minute to hook it up to the tester and another
minute to return it to the rack where a Battery Minder
will top it off. When I grab a battery and saddle up to
do a task, I know what the battery can be expected to
do for me.
A lot of folks got upset at my recommendation for yearly
replacement of the ship's battery. But if you can buy
an 18/20 AH battery for about $30 then what is the cost
of ownership trade off to test the battery perhaps one
or two times to determine serviceability over the lifetime
of the battery?
Obviously, the more expensive the battery, the more likely
it is that acquiring and using test equipment becomes
attractive. Richard didn't describe his own operating
requirements for load and endurance but it seems likely
that he might use the battery for another year. Assuming
he tests in another year and then discards the battery,
his cost of ownership is ($acquisition$) + 2x($test$)
divided by 2.
Nobody is in a position to make any really useful recommendations
for battery replacement without having a lot of data about
how you expect your battery to perform and knowing
what your $time$ is worth when expended on the task
of battery maintenance.
Bob . . .
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