Today's Message Index:
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1. 08:56 AM - Re: Aerovoltz and Starter Draw (was Z-17 Schematic) (Robert L. Nuckolls, III)
2. 10:14 AM - Battery choice (Dj Merrill)
3. 10:57 AM - Re: Battery choice (Charlie England)
4. 11:05 AM - Re: Battery choice (Robert L. Nuckolls, III)
5. 11:11 AM - Re: Battery choice (Jeff Luckey)
6. 06:19 PM - Re: Battery choice (Dj Merrill)
Message 1
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| Subject: | Re: Aerovoltz and Starter Draw (was Z-17 Schematic) |
At 07:45 PM 5/21/2014, you wrote:
><mrcc1234@sbcglobal.net>In
>
>The Aerovoltz is in the mail as they say and I can report the
>details as soon as I get it.
>You probably spell out how to build the cap check curves in your
>book so I will look into that.
Actually the task is a bit more complicated. I did a report
on a 'leading technology' battery
http://tinyurl.com/qe6yy6c
to explore its performance numbers. Turns out to
be a pretty good 100AH battery for an RV or
some such . . .
http://tinyurl.com/nf47dgk
. . . but demonstrates 0.0063 ohms
internal resistance. A 24-volt incarnation of
this same battery would give us about 38AH at the
1-hour rate in an airplane . . . but would
have 0.024 ohms internal resistance! It wouldn't
crank its way out of a wet paper sack.
Gathering this class of data takes some test
equipment. If you would volunteer your battery
to receive about 4 charge-recharge cycles in accordance
with manufacturer's recommendations for the
test, I'd be pleased to gather and publish the
data to the OBAM aviation community.
>Good to know that 4awg should be sufficient at least that saves a
>little weight. I was having trouble figuring out how much current to
>assume was being drawn during a cold start to base the wire size calc on.
Inrush can be higher but a 200A average cranking
effort is about right . . . and by "cold" we mean
below freezing when you probably wouldn't want
to go flying anyhow. As I recall, cabin heat in
that airplane is . . . shall we say . . . marginal?
Bob . . .
Message 2
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I'm trying to decide on a battery. Many people are using the Odyssey
PC680 with good results. It is a somewhat expensive battery:
http://www.apexbattery.com/odyssey-pc680-marine-battery-marine-batteries-odyssey-marine-batteries.html?utm_source=googlepepla&utm_medium=adwords&id=18283950120&gclid=CIaiifviv74CFXRo7AodqxYANA
In our UPS units we use a UB12180 battery (or equivalent), which is 1/3
the cost of the PC680 and has better specs:
http://www.apexbattery.com/abiomed-bvs-5000-biventricular-support-battery-sealed-lead-acid-batteries-abiomed-batteries.html
Are there any reasons why I should not be using this battery in my
aircraft?
My battery is mounted in the tail section, and it is not exposed to the
direct heat and vibration of the engine compartment, if that makes any
difference.
-Dj
--
Dj Merrill - N1JOV - VP EAA Chapter 87
Sportsman 2+2 Builder #7118 N421DJ - http://deej.net/sportsman/
Glastar Flyer N866RH - http://deej.net/glastar/
Message 3
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| Subject: | Re: Battery choice |
On 5/22/2014 12:13 PM, Dj Merrill wrote:
>
> I'm trying to decide on a battery. Many people are using the Odyssey
> PC680 with good results. It is a somewhat expensive battery:
>
> http://www.apexbattery.com/odyssey-pc680-marine-battery-marine-batteries-odyssey-marine-batteries.html?utm_source=googlepepla&utm_medium=adwords&id=18283950120&gclid=CIaiifviv74CFXRo7AodqxYANA
>
> In our UPS units we use a UB12180 battery (or equivalent), which is 1/3
> the cost of the PC680 and has better specs:
>
> http://www.apexbattery.com/abiomed-bvs-5000-biventricular-support-battery-sealed-lead-acid-batteries-abiomed-batteries.html
>
> Are there any reasons why I should not be using this battery in my
> aircraft?
>
> My battery is mounted in the tail section, and it is not exposed to the
> direct heat and vibration of the engine compartment, if that makes any
> difference.
>
> -Dj
>
I did some digging a few years ago, & it seems that UPS and
wheelchair/scooter batteries' chemistry is tweaked a bit differently
from starting batteries. They are intended to be discharged somewhat
slower, with deeper discharge (think 'marine' battery), but struggle a
bit to deliver high short term bursts of energy, like you need to start
a big engine. The easy way to spot the difference (if you can get full
specs) is to compare the internal resistance numbers. For starting,
lower is better. Another, less reliable way is to just look at the
terminals. Many UPS batteries have terminals that are much too small to
handle 200+ amps. I've been using 'brand-x' batteries in my planes for
many years, & my experience is that some of the 18 AH rated batteries
like the one you linked might struggle just a bit with a higher
compression a/c engine, but you can usually buy a 20AH or 22AH model
from the same series with almost identical case size, & it will provide
almost enough 'grunt' to taxi the plane with the starter. :-) Price is
still much lower than the Odyssey. Model number will be something like
'12200' or '12220' instead of 12180 (the 18 indicated the AH rating).
Most on-line battery sales operations now sell 'brand x'
motorcycle/watercraft/etc starting batteries that are drop-in
replacements for the Odyssey; that's the easiest way to get a suitable
substitute at a lower price.
FWIW,
Charlie
Message 4
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| Subject: | Re: Battery choice |
In our UPS units we use a UB12180 battery (or equivalent), which is 1/3
the cost of the PC680 and has better specs:
http://www.apexbattery.com/abiomed-bvs-5000-biventricular-support-battery-sealed-lead-acid-batteries-abiomed-batteries.html
Are there any reasons why I should not be using this battery in my aircraft?
None that I can think of . . . without a doubt
the freshly installed battery will perform
satisfactorily. The 18 Ah battery and form-factor
have proven adequate to a huge segment
of OBAM aircraft. The question that nobody can
answer is cost of ownership for this battery.
Figure sale price + shipping + maintenance costs
for the less expensive battery. Is it likely that
the more expensive battery will have a lower cost
per flight hour than 3x the cheaper one? Probably
not. 2x the cheaper one? Again, probably not. But
that assertion is not supported with any data for
either robustness + your working environment +
possibly replacing the battery after cap-checks
show it to be unsuitable for further flight.
The risks are low. Try the less expensive battery
and keep notes. Without having hard numbers on
relative performance to stack against numbers for
how YOU need to use the battery, nobody has the
tools to either recommend or discourage the
experiment.
Let us know what you decide and what you find out
in a year or so. Got a load tester? You might want
to own one of these things.
http://tinyurl.com/3gnnwrt
This modern incarnation of 1930's technology is to
batteries as a hammer is to nails.
Bob . . .
Message 5
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| Subject: | Re: Battery choice |
DJ,=0A=0AI wonder if those stats for the cheaper battery are a little "opti
mistic"?=0A=0A=0A-Jeff=0A=0A=0A________________________________=0A From: Dj
Merrill <deej@deej.net>=0ATo: aeroelectric-list@matronics.com =0ASent: Thu
rsday, May 22, 2014 10:13 AM=0ASubject: AeroElectric-List: Battery choice
t>=0A=0A--- I'm trying to decide on a battery.- Many people are usi
ng the Odyssey=0APC680 with good results.- It is a somewhat expensive bat
tery:=0A=0Ahttp://www.apexbattery.com/odyssey-pc680-marine-battery-marine-b
atteries-odyssey-marine-batteries.html?utm_source=googlepepla&utm_medium
=adwords&id=18283950120&gclid=CIaiifviv74CFXRo7AodqxYANA=0A=0A--
- In our UPS units we use a UB12180 battery (or equivalent), which is 1/3
=0Athe cost of the PC680 and has better specs:=0A=0Ahttp://www.apexbattery.
com/abiomed-bvs-5000-biventricular-support-battery-sealed-lead-acid-batteri
es-abiomed-batteries.html=0A=0A--- Are there any reasons why I should
not be using this battery in my=0Aaircraft?=0A=0A--- My battery is m
ounted in the tail section, and it is not exposed to the=0Adirect heat and
vibration of the engine compartment, if that makes any=0Adifference.=0A=0A-
Dj=0A=0A-- =0ADj Merrill - N1JOV - VP EAA Chapter 87=0ASportsman 2+2 Builde
r #7118 N421DJ - http://deej.net/sportsman/=0AGlastar Flyer N866RH - http:/
=
Message 6
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| Subject: | Re: Battery choice |
On 5/22/2014 1:56 PM, Charlie England wrote:
> but you can usually buy a 20AH or 22AH model from the same series with
> almost identical case size, & it will provide almost enough 'grunt' to
> taxi the plane with the starter. :-) Price is still much lower than
> the Odyssey. Model number will be something like '12200' or '12220'
> instead of 12180 (the 18 indicated the AH rating).
Charlie,
Good advice, thanks!
$44 including shipping from Amazon for the UB12220 battery, 12v 22Ah in
the same form factor.
A plus is that it is 9 lbs lighter than the 25 Ah battery it will be
replacing (a B and C model BC110-1).
Bob,
I will report back to the list as to how it performs. I have a low
compression 150hp Lycoming O-320 with a light weight starter, so it
should hopefully turn it over with no difficulty.
-Dj
--
Dj Merrill - N1JOV - VP EAA Chapter 87
Sportsman 2+2 Builder #7118 N421DJ - http://deej.net/sportsman/
Glastar Flyer N866RH - http://deej.net/glastar/
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