Today's Message Index:
----------------------
1. 03:21 AM - Sharing photos on the Aeroelectric List (Bob Lee)
2. 06:19 AM - Re: landing lights (Eric M. Jones)
3. 08:55 AM - Charging of back-up battery (Stig Holm)
4. 10:09 AM - Re: Automobile lights (James Foerster)
5. 10:25 AM - Re: Charging of back-up battery (Charlie & Tupper England)
6. 10:42 AM - Relay for Crowbar protection (Paul McAllister)
7. 10:47 AM - Re: Charging of back-up battery (Robert L. Nuckolls, III)
8. 11:26 AM - Re: Charging of back-up battery (James Foerster)
9. 12:51 PM - Re: Re: Automobile lights (Richard E. Tasker)
10. 03:15 PM - Re: Relay for Crowbar protection (Robert L. Nuckolls, III)
11. 03:32 PM - Re: Charging of back-up battery (Robert L. Nuckolls, III)
Message 1
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| Subject: | Sharing photos on the Aeroelectric List |
--> AeroElectric-List message posted by: "Bob Lee" <bob@flyboybob.com>
'OC' Baker wrote
"I have no electronic picture capability".
You don't need any these days OC. Just ask for a CD when you get your film
developed. All of the film developing machines are electronic to allow the
operator to adjust the color. At the shop I go to it's only $2 for my wife
to get CDs from her film. She still likes her point-n-shoot. I have heard
of some places charging as much as $5 but it's still a good deal if you
consider postage and packaging and duplicate printing charges to make
additional copies to send to others.
Regards,
Bob Lee
______________________________
N52BL KR2 Suwanee, GA 30024
91% done only 51% to go!
Phone/Fax: 770/844-7501
mailto:bob@flyboybob.com
http://flyboybob.com
Message 2
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| Subject: | Re: landing lights |
--> AeroElectric-List message posted by: "Eric M. Jones" <emjones@charter.net>
I have a fuzzy magazine photo of a late 1930's twin-engine German bomber with what
appear to be landing lights in the propeller spinners. This looks like a whacky
idea but heck--in aviation there are lots of whacky ideas! Consider-- (assuming
these even WERE lights) that these were unlikely to be sealed beams, just
spun and polished aluminum reflectors with (I'm speculating) axial filament
lamps powered by the same power scheme as the electrically de-iced props, (and
maybe electric blade pitch). Now that wouldn't be so whacky...eh?
Regards,
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge MA 01550-2705
Phone (508) 764-2072
Email: emjones@charter.net
"When dealing with the enemy, it helps if he thinks you're a little bit crazy."
--Gen. Curtis LeMay
Message 3
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| Subject: | Charging of back-up battery |
--> AeroElectric-List message posted by: "Stig Holm" <stig.holm@telia.com>
I'm building an RV6 with an O-320 which I have decided to equip with dual electronic
ignition (Lightspeed). For redundancy I=B4m installing a backup battery
which is normally off-line (both systems fed by the main electric system) but
continously charged from the main system through a diode (Aeroelectric). This
is per the plans as suggested by mr. Klaus Savier.
The main system battery is a Odyssey which means that voltage of the main system
should be around 14.2 volts. The back-up battery should normally have about
13.8 volts which also is what it will get because of the .3 - .4 volts drop over
the diode.
My problem is that the backup battery (sealed 2.2 Ah lead-acid battery normally
found as back-up battery in alarm systems) has a max charging current of .66
amps and if the voltage of this battery for some reason has dropped substancially
below 13.8 volts, the charging current from the main system will easily damage
the backup battery. I will therefore need some sort of charging limiter
to maximize the charging current to .66 amps.
How do I accomplish this?
Regards
Stig Holm
Message 4
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| Subject: | Re: Automobile lights |
--> AeroElectric-List message posted by: "James Foerster" <jmfpublic@attbi.com>
<A caveat on HID lamps . . . we installed on the AGATE Bonanza
at RAC a couple of years ago. It was the Lopresti kit I believe.
Really nice for night ops . . . however . . . because its color
temperature is so much higher that incandescent lamps, it's
practically invisible against daylight blue sky. Not nearly
so practical for daytime collision avoidance as lamps with
filaments in them.>
Bob, thanks for this useful observation. Saves me money, and directs me to a system
that could use the wig-wag system. The little MR-11 or even MR-16 lamps
are cheap, bright, available with a glass cover in some models, and available
surplus, so you can experiment cheaply. It is easy to fabricate a holder out
of sheet aluminum.
here is a source http://www.allelectronics.com/cgi-bin/category.cgi?category320150&typestore They have sockets in the same catalog.
Jim Foerster
Message 5
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| Subject: | Re: Charging of back-up battery |
--> AeroElectric-List message posted by: Charlie & Tupper England <cengland@netdoor.com>
Stig Holm wrote:
>--> AeroElectric-List message posted by: "Stig Holm" <stig.holm@telia.com>
>
>I'm building an RV6 with an O-320 which I have decided to equip with dual electronic
ignition (Lightspeed). For redundancy I=B4m installing a backup battery
which is normally off-line (both systems fed by the main electric system) but
continously charged from the main system through a diode (Aeroelectric). This
is per the plans as suggested by mr. Klaus Savier.
>
>The main system battery is a Odyssey which means that voltage of the main system
should be around 14.2 volts. The back-up battery should normally have about
13.8 volts which also is what it will get because of the .3 - .4 volts drop over
the diode.
>
>My problem is that the backup battery (sealed 2.2 Ah lead-acid battery normally
found as back-up battery in alarm systems) has a max charging current of .66
amps and if the voltage of this battery for some reason has dropped substancially
below 13.8 volts, the charging current from the main system will easily
damage the backup battery. I will therefore need some sort of charging limiter
to maximize the charging current to .66 amps.
>How do I accomplish this?
> Regards
>Stig Holm
>
If you are handy with a soldering iron, you might look at
http://www.st.com/stonline/books/pdf/docs/1318.pdf
Scroll about 2/3 of the way down to figure 27.
Lots of variations on this type of device are available; this was the
1st one I hit by typing 'constant current regulator' into Google.
Current regulators can even be built using 3-terminal voltage regulators
(~$1 each) if my memory isn't playing tricks on me.
A plug-N-play device is likely to be rather expensive, but rolling your
own shouldn't be more than $20 worst case.
Charlie
Message 6
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| Subject: | Relay for Crowbar protection |
--> AeroElectric-List message posted by: "Paul McAllister" <paul.mcallister@qia.net>
Hi Bob,
I am looking for a recommendation for a relay. I have a Rotax 912S which has a
permanent magnet alternator with a (claimed) peak output of 25 amps.
To use your OVP module I will need a relay, will the S704-1 do the job or will
it be a bit small? Are permanent magnet alternator likely to generate over voltage
situations?. The reason I ask is that the introduction of a relay will
be an additional failure point.
Thanks, Paul
Message 7
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| Subject: | Re: Charging of back-up battery |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 05:55 PM 6/21/2003 +0200, you wrote:
>--> AeroElectric-List message posted by: "Stig Holm" <stig.holm@telia.com>
>
>I'm building an RV6 with an O-320 which I have decided to equip with dual
>electronic ignition (Lightspeed). For redundancy I=B4m installing a backup
>battery which is normally off-line (both systems fed by the main electric
>system) but continously charged from the main system through a diode
>(Aeroelectric). This is per the plans as suggested by mr. Klaus Savier.
>
>The main system battery is a Odyssey which means that voltage of the main
>system should be around 14.2 volts. The back-up battery should normally
>have about 13.8 volts which also is what it will get because of the .3 -
>.4 volts drop over the diode.
>
>My problem is that the backup battery (sealed 2.2 Ah lead-acid battery
>normally found as back-up battery in alarm systems) has a max charging
>current of .66 amps and if the voltage of this battery for some reason has
>dropped substancially below 13.8 volts, the charging current from the main
>system will easily damage the backup battery. I will therefore need some
>sort of charging limiter to maximize the charging current to .66 amps.
>How do I accomplish this?
> Regards
>Stig Holm
What kind of batteries are you installing in your airplane?
The probability of a sustained charging current above .66A
for a small, backup battery is low. If it's an RG battery
totally unloaded while the airplane is parked, frequency
and duration of charging events that exceed .66A are small
and short.
I prefer a "hard" connection as opposed to diodes . . .
If you have active notification of low voltage, there's
no reason you can't simply parallel a standby battery
with the main battery to provide redundant power sources
as described in appendix A of the 'Connection
downloadable at
http://www.aeroelectric.com/articles/Rev10/z10.pdf
and described in Figure 17-6 of
http://www.aeroelectric.com/articles/Rev9/ch17-9.pdf
If you're considering a main battery like those
installed in most OBAM aircraft (24 a.h. flooded)
then you might reconsider a pair of 17 a.h. RG
batteries wired like figure 17-6, connected in parallel
for all normal operations but with provisions for
isolating the two batteries during alternator-out
operations. You can even automate this functionality
with an Aux Battery Management system like that
described at:
http://www.aeroelectric.com/articles/lvwarn/LVWarn-ABMM.html
and
http://www.aeroelectric.com/articles/lvwarn/9021-620.pdf
or offered assembled and tested at
http://www.aeroelectric.com/Catalog/AEC/9005/9005.html
and wired per instructions which you can peek at
by downloading
http://www.aeroelectric.com/Catalog/AEC/9005/9005-701B.pdf
When you have two, relatively robust batteries, you can
use BOTH for cranking and rotate the main battery into
the aux slot every annual for replacment of the main battery.
This combination of batteries and battery maintenance philosophy
combined with a well proven alternator like the B&C L-series
or any other NiponDenso product will offer system reliability
that far exceeds anything flying in certified aircraft today.
Bob . . .
Message 8
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| Subject: | Re: Charging of back-up battery |
--> AeroElectric-List message posted by: "James Foerster" <jmfpublic@attbi.com>
Stig Holm wrote:
My problem is that the backup battery (sealed 2.2 Ah lead-acid battery normally
found as back-up battery in alarm systems) has a max charging current of .66
amps and if the voltage of this battery for some reason has dropped substancially
below 13.8 volts, the charging current from the main system will easily damage
the backup battery. I will therefore need some sort of charging limiter
to maximize the charging current to .66 amps.
Stig: if your little battery drops its voltage, it will quickly rise to 13.8 volts
with just a small percent of recharge. To limit the initial surge, a series
resistor should work well. Your minimum voltage for a dead battery is 10
volts, and you will have a maximum of 13.5 with a charge voltage of 14.2 dropped
0.7 in the series silicon diode. RE/I, and if you limit the max current to
0.66 amps, R(13.5-10)/0.667 ohms. However, if it were my plane, I would limit
the max current to something larger, such as the "1/2 hour rate" of 4.4 amps
for a 2.2 amp-hour battery. R0.8 ohms for this. This max current flows only
briefly as the battery voltage will rise to near 13.8 volts. I would worry that
you might not fully recharge this battery due to limited voltage. A Schottky
diode with only 0.3 to 0.4 voltage drop might be better.
You will need to fuse this charge circuit. The 0.8 ohm resistor worst case disipates
15.5 watts, but this might be for only 3 seconds. A 10 watt resistor
should do fine.
See http://www.allelectronics.com/matrix/Power_Resistors.html for a selection with pictures. The 0.75 ohm 10 watt "sand" resistor at 3 for a dollar should do.
Jim Foerster
Message 9
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| Subject: | Re: Automobile lights |
--> AeroElectric-List message posted by: "Richard E. Tasker" <retasker@optonline.net>
I agree. The light you have referenced is a 25 degree spot. If you
want something tighter (12 degrees) Mcmaster-Carr sells a selection of
wattages and angles for $3.33 each. Be aware that the glass covers
reduce the total light output.
Dick Tasker
James Foerster wrote:
>--> AeroElectric-List message posted by: "James Foerster" <jmfpublic@attbi.com>
>
><A caveat on HID lamps . . . we installed on the AGATE Bonanza
> at RAC a couple of years ago. It was the Lopresti kit I believe.
> Really nice for night ops . . . however . . . because its color
> temperature is so much higher that incandescent lamps, it's
> practically invisible against daylight blue sky. Not nearly
> so practical for daytime collision avoidance as lamps with
> filaments in them.>
>
>Bob, thanks for this useful observation. Saves me money, and directs me to a
system that could use the wig-wag system. The little MR-11 or even MR-16 lamps
are cheap, bright, available with a glass cover in some models, and available
surplus, so you can experiment cheaply. It is easy to fabricate a holder out
of sheet aluminum.
>
>here is a source http://www.allelectronics.com/cgi-bin/category.cgi?category320150&typestore They have sockets in the same catalog.
>
>Jim Foerster
>
>
>
>
Message 10
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| Subject: | Re: Relay for Crowbar protection |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 12:39 PM 6/21/2003 -0500, you wrote:
>--> AeroElectric-List message posted by: "Paul McAllister"
><paul.mcallister@qia.net>
>
>Hi Bob,
>
>I am looking for a recommendation for a relay. I have a Rotax 912S which
>has a permanent magnet alternator with a (claimed) peak output of 25 amps.
>
>To use your OVP module I will need a relay, will the S704-1 do the job or
>will it be a bit small? Are permanent magnet alternator likely to
>generate over voltage situations?. The reason I ask is that the
>introduction of a relay will be an additional failure point.
It will be fine. Yes, the relay is an increase in parts count
and a reduction in system reliability. Do you plan to carry and
maintain enough battery to use up fuel aboard battery only?
I think system reliability reduction is a small price to pay
since you're trading a failure that cooks things for a failure
that is passive. There are numerous OTHER things that can
take the alternator off line besides failure of the ov protection
system . . . one would do well to be tolerant of all those failures
too.
Bob . . .
Message 11
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| Subject: | Re: Charging of back-up battery |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
>
>If you are handy with a soldering iron, you might look at
>
>http://www.st.com/stonline/books/pdf/docs/1318.pdf
>
>Scroll about 2/3 of the way down to figure 27.
>
>Lots of variations on this type of device are available; this was the
>1st one I hit by typing 'constant current regulator' into Google.
>Current regulators can even be built using 3-terminal voltage regulators
>(~$1 each) if my memory isn't playing tricks on me.
>
>A plug-N-play device is likely to be rather expensive, but rolling your
>own shouldn't be more than $20 worst case.
. . . check out a characteristic of this device on page
3-12. It's delta-V, input-output, second one up from bottom
of chart. This tells us that the absolute minimum headroom
(read EXCESS voltage) for this device to operate is on the
order of 2.5 volts. To use this device as an active constant-
current source to charge a battery at 13.8 would require a source
voltage of 16.3 or better.
The people who make little batteries will often put
specifications or limits on them intended to improve battery
life. If small RG batteries are used in a BACKUP (read
"shucks aunt Martha, the alternator and main battery are
BOTH crapped . . . now what do I do?") they should be
renewed every year. Small RG batteries are not known for long
service life. I use them in the recovery parachute systems
on Hawker Horizon and Premier . . . they get LOAD tested
every preflight and the flight does not launch without
both batteries testing good. I've had some make it for a
year and some only lasted a few months. The batteries
in the parachute system are hard-connected to ship's
bus via relay contact driven by (you guessed it) a
28v ABMM module.
This is one reason why I favor the dual, 17 a.h. battery
installation with yearly swapout over incorporating
any kind of dinky "standby" battery. If you're REALLY
depending on that battery to bail you out of a bad
situation it is entitled to extra-ordinary maintenance
and operating attention. Better yet, design your system
with more attention to failure tolerance and improved
robustness. For me, robustness comes from having an
aux battery that served it's first year of duty as
the main battery and will be outta here after no
more than 24 months of service.
Bob . . .
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