Today's Message Index:
----------------------
1. 05:58 AM - Z-22 relay question (Mdharfst@cs.com)
2. 07:32 AM - Re: Batteries in series and parallel (Mark & Lisa)
3. 07:34 AM - Re: Batteries in series and parallel (Mark & Lisa)
4. 09:26 AM - Re: Batteries in series and parallel (Jerry Grimmonpre)
5. 11:32 AM - Re: Batteries in series and parallel (Robert L. Nuckolls, III)
6. 11:35 AM - Re: Batteries in series and parallel (Eric M. Jones)
7. 09:37 PM - Re: Batteries in series and parallel (Robert L. Nuckolls, III)
Message 1
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| Subject: | Z-22 relay question |
--> AeroElectric-List message posted by: Mdharfst@cs.com
Listers
I have a problem I need advice on. My electrical system is from an older version
of Bob's drawings but fits the current Z-11 drawing pretty closely with a Z-22
substitution for the way I wire the starter run on relay. I need to replace
the S704-1 relay which has gone bad. Can I use a standard starter contactor
in place of the smaller lighter relay? It seems that the wiring logic should
be the same regardless of whether the smaller or larger relay is used.
Thanks in advance.
Michael Harfst N9TZ 165 Hrs
Message 2
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| Subject: | Re: Batteries in series and parallel |
--> AeroElectric-List message posted by: "Mark & Lisa" <marknlisa@hometel.com>
Bob,
Thanks for the info, I was pretty sure I'd heard of such a setup before,
just don't know exactly how to arrange it.
Mark & Lisa Sletten
Legacy FG N828LM
http://www.legacyfgbuilder.com
--> AeroElectric-List message posted by: BobsV35B@aol.com
Good Morning Mark,
For What It Is Worth, back when I was flying LaBelle Caravelle, there
was a
big handle immediately to my left and just below the side cockpit
window which
switched the batteries from the parallel mode into a series
arrangement to
provide sufficient power to start the engines.
Message 3
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| Subject: | Re: Batteries in series and parallel |
--> AeroElectric-List message posted by: "Mark & Lisa" <marknlisa@hometel.com>
Dj,
I'd considered this approach, but if I'm forced to have two batteries I'd
like to use both of them for inflight duties in lieu of the second
engine-driven power source (see my original post). If I don't have both
batteries available I'd need two alternators AND two batteries; up goes the
weight and complexity. Thanks for the idea tho...
Regards,
Mark & Lisa Sletten
Legacy FG N828LM
http://www.legacyfgbuilder.com
--> AeroElectric-List message posted by: Dj Merrill
<deej@thayer.dartmouth.edu>
Just a random thought - if you do not mind dedicating
one battery for just the starter, you could have just a single
battery in-line with your starter contactor (or whatever device
you choose to do this function), so when you engage the contactor,
you get the 12v from the "regular" battery and feed it in
series with the "starter" battery for 28v. Everything else
only gets the 12v from the "regular" battery.
Message 4
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| Subject: | Re: Batteries in series and parallel |
--> AeroElectric-List message posted by: "Jerry Grimmonpre" <jerry@mc.net>
Hi Mark ...
Just wanted to relate to you what my Ford tractor mechanic did to modify my
tractor and this mod was acceptable practice.
The mod involved changing out the 6Volt generator, battery, and light bulbs
for 12V alternator, battery, and light bulbs. The 6V starter was left as is
... 6V. The gas engine started "right now" with a very fast spin from the
starter, as one could imagine. There was no down side to this mod. The
tractor was used for 20 years in this configuration and never had a starter
problem. I'm not advocating anyone put a high value airplane starter into
this environment ... just a data point.
Jerry Grimmonpre
Message 5
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| Subject: | Re: Batteries in series and parallel |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 11:24 AM 6/25/2005 -0500, you wrote:
>--> AeroElectric-List message posted by: "Jerry Grimmonpre" <jerry@mc.net>
>
>Hi Mark ...
>Just wanted to relate to you what my Ford tractor mechanic did to modify my
>tractor and this mod was acceptable practice.
>
>The mod involved changing out the 6Volt generator, battery, and light bulbs
>for 12V alternator, battery, and light bulbs. The 6V starter was left as is
>... 6V. The gas engine started "right now" with a very fast spin from the
>starter, as one could imagine. There was no down side to this mod. The
>tractor was used for 20 years in this configuration and never had a starter
>problem. I'm not advocating anyone put a high value airplane starter into
>this environment ... just a data point.
This was a common approach taken by some hot-rodders in my
school days during the transition from 6->12 and gen->alt
hardware. High compression 6v engines were often "bumped up"
to 8v systems by purchasing the right 4-cell battery and
tightening the spring on the voltage regulator control
relay. This "fixed" a weak starter problem on high-compression
engines. Later, many builders left their 6v starters in place
after converting the rest of the vehicle to 12v. I did such
an upgrade for a friend of mine on a '38 Merc Convertable.
We installed a 60A alternator on a flat-head v8 and even
put an aftermarket, under-dash a/c in the car. He took a
number of prizes at local shows for his finished project.
The car did just fine with the original 6v starter installed.
Starter motors of the era were series wound and VERY tolerant
of increased operating voltage.
Bob . . .
Message 6
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| Subject: | Re: Batteries in series and parallel |
--> AeroElectric-List message posted by: "Eric M. Jones" <emjones@charter.net>
--> AeroElectric-List message posted by: "Mark & Lisa"
<marknlisa@hometel.com>
>a) Power a 24V starter from a pair of 12V batteries, or.......
Mark,
Here a schematic to do the job in the standard series-parallel way:
http://www.periheliondesign.com/downloads/12-24V_System.pdf
However, if it were my bird I would question the idea that Deltahawk can't
do the job at 12V. Here's why--
The voltage of a starting system in not as important as the system's ability
to delivery current to the starter. This is also a function of the
resistance of the battery and connections, etc. An Ultracapacitor in
parallel with the battery and close to the starter motor is now often used
to start diesel engines. These go for $20/Farad (12V) and the cost is in
freefall. I'd try one of these on the Deltahawk.
Regards,
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge MA 01550-2705
Phone (508) 764-2072
Email: emjones@charter.net
"Every act of conscious learning requires the willingness to suffer an
injury to one's self-esteem...."
-Thomas Szasz
Message 7
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| Subject: | Re: Batteries in series and parallel |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 09:33 AM 6/25/2005 -0500, you wrote:
>--> AeroElectric-List message posted by: "Mark & Lisa" <marknlisa@hometel.com>
>
>Dj,
>
>I'd considered this approach, but if I'm forced to have two batteries I'd
>like to use both of them for inflight duties in lieu of the second
>engine-driven power source (see my original post). If I don't have both
>batteries available I'd need two alternators AND two batteries; up goes the
>weight and complexity. Thanks for the idea tho...
>
>Regards,
What you're asking for has been done on several aircraft
in the past . . . but it needs to be accomplished with
careful attention to the potential for shorting batteries
with VERY hard faults when the system is dependent on
relay transition times for avoiding faults. Further,
the batteries should be fitted with ANL limiters such
that (1) opening a limiter doesn't take BOTH batteries off
line and (2) things come to an orderly conclusion in case
of a stuck contactor. Relay timing issues can be washed
out my design. I'll offer the following suggestion:
http://www.aeroelectric.com/PPS/Engine/Starter/24V_Starter_14V_System.pdf
Bob . . .
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