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Dennis Johnson
Joined: 10 Jan 2006 Posts: 89 Location: N. Calif.
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Posted: Tue Sep 13, 2011 12:30 pm Post subject: Report on New Power Supply |
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A few weeks ago I reported that I had bought this 12 volt power supply:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=250852141183
I wanted it to power my instrument panel while doing navigation data updates, cycling the wing flaps, and other tasks that would otherwise take power from the airplane's battery. I have one that appeared similar to this one that works perfectly.
However, the new one seems pretty close to useless for my needs. If I adjust the output voltage higher than about 12.4 volts DC, the power supply goes into overload and makes a quiet snapping sound about once per second and the output amps go to zero (while it's connected to my airplane's battery).
The literature claims the output voltage is adjustable from 10.8 to 13.2 volts and that the input voltage is from 100 to 264 VAC. However, the one I received is labeled 176 - 264 volts AC. My guess is that since my input is 120 volts, the power supply cannot achieve the stated performance.
I only paid $15 for it, including shipping, so I'm not all that unhappy. I'm sure I'll find a use for it somewhere. I just wanted to pass along that the power supply I received doesn't seem to be suitable for 12 volt airplanes. I could complain to the seller, but when I emailed them to ask how to connect it, since it came without instructions, my emails was never answered and it's now worth my time to fight for $15.
I might look at battery maintainers at Wal Mart instead. Since I'm done building, I don't ground test heavy loads (like raising and lowering the landing gear) that often. A battery maintainer is probably all I need anyway.
Dennis
[quote][b]
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retasker(at)optonline.net Guest
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Posted: Tue Sep 13, 2011 7:10 pm Post subject: Report on New Power Supply |
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Interestingly, if you look closely at the photo on the eBay listing you can see printed on the top of the supply "AC 176-264V". Not that anyone would notice that when bidding...
You should at least give feedback to eBay about this. How many others will purchase this supply just like you did and discover the same thing as you did?
Dick Tasker
Dennis Johnson wrote:
Quote: | A few weeks ago I reported that I had bought this 12 volt power supply:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=250852141183 <http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=250852141183>
I wanted it to power my instrument panel while doing navigation data updates, cycling the wing flaps, and other tasks that would otherwise take power from the airplane's battery. I have one that
appeared similar to this one that works perfectly.
However, the new one seems pretty close to useless for my needs. If I adjust the output voltage higher than about 12.4 volts DC, the power supply goes into overload and makes a quiet snapping sound
about once per second and the output amps go to zero (while it's connected to my airplane's battery).
The literature claims the output voltage is adjustable from 10.8 to 13.2 volts and that the input voltage is from 100 to 264 VAC. However, the one I received is labeled 176 - 264 volts AC. My
guess is that since my input is 120 volts, the power supply cannot achieve the stated performance.
I only paid $15 for it, including shipping, so I'm not all that unhappy. I'm sure I'll find a use for it somewhere. I just wanted to pass along that the power supply I received doesn't seem to be
suitable for 12 volt airplanes. I could complain to the seller, but when I emailed them to ask how to connect it, since it came without instructions, my emails was never answered and it's now worth
my time to fight for $15.
I might look at battery maintainers at Wal Mart instead. Since I'm done building, I don't ground test heavy loads (like raising and lowering the landing gear) that often. A battery maintainer is
probably all I need anyway.
Dennis
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mrspudandcompany(at)veriz Guest
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Posted: Wed Sep 14, 2011 3:47 am Post subject: Report on New Power Supply |
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Interestingly, if you look closely at the photo on the eBay listing you can
see printed on the top of the supply "AC 176-264V". Not that anyone would
notice that when bidding...
Yes, I noticed this when it was posted a couple of weeks ago
and I sent a question to the seller. The answer back was 100 - 264V input.
If you look at their spec sheet on eBay it does say 100 -
264V even though the pic shows 176 - 264V.
If you have 220VAC available in your shop you might try
running it at the higher voltage.
There is a lot of Chinese "junk" out there. You just have
to weigh the risk to the reward.
Roger
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nuckolls.bob(at)aeroelect Guest
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Posted: Wed Sep 14, 2011 5:28 am Post subject: Report on New Power Supply |
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At 03:24 PM 9/13/2011, you wrote:
When shopping for an AC mains power supply to
ground run your project, consider the following:
Ideally, you're wanting to emulated an alternator,
not a battery. A supply rated at 15 volts instead
of 12 volts is likely to be adjustable down to the
14.2 to 14.6 volt range typical of most systems.
Also, go for the biggest supply you can get within
your means. This supply
http://tinyurl.com/43yuvhl
is a 15v, 350 Watt device with a cooling fan. I've
used a number of supplies from this company for other
projects and found them to be of good value.
Finally, consider adding an output isolation diode to
disconnect the supply from the battery when it is not
being powered. I believe this was suggested and illustrated
in the form of a relay or contactor by another AEC_Lister a
some days ago. Either works.
Bob . . .
////
(o o)
===========o00o=(_)=o00o=========
< Go ahead, make my day . . . >
< show me where I'm wrong. >
=================================
[quote][b]
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nuckolls.bob(at)aeroelect Guest
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Posted: Wed Sep 14, 2011 8:04 am Post subject: Report on New Power Supply |
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Quote: | Also, go for the biggest supply you can get within
your means. This supply
http://tinyurl.com/43yuvhl
is a 15v, 350 Watt device with a cooling fan. I've
used a number of supplies from this company for other
projects and found them to be of good value. |
An AE-List member reminded me that these are "switchmode"
power supplies with a not quite zero risk of interference.
These are probably designed and tested to FCC Part 15
performance rules. FCC15 allows the device to be a 'minor'
problem but the user is responsible for discontinuing use
if it interferes with other, protected services.
The OBAM aircraft is not likely to have a problem. The
greatest potential victims are ADF and LORAN which are
essentially extinct. But be aware that some systems
may object to power produced by these devices. The
easy test is to momentarily unplug the power supply
and run battery only to see if the problem goes away.
They're not going to have a conducted emissions problem,
only radiated and that's very low risk.
Bob . . .
////
(o o)
===========o00o=(_)=o00o=========
< Go ahead, make my day . . . >
< show me where I'm wrong. >
=================================
[quote][b]
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skywagon
Joined: 11 Feb 2006 Posts: 184
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Posted: Wed Sep 14, 2011 3:53 pm Post subject: Report on New Power Supply |
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Hi Bob,
Several months ago I too purchased one of these units (or similar) as it seemed like a great method to power up the panel when working on the electrical problems, changes, etc. Rated at 13.5 v., 350W, the first unit I received (they come from China) would not hold voltage when loaded with about 5-6 amps of panel load. It started at about 13.4 v. and dropped to 12.4 when the panel was powered up. I contacted the seller and he said to return it and he would replace it.
I did and about 4 wks later he sent me a replacement. It is functioning in a similar fashion. No load about 13.4 and mild load drops to 12.75. Still Ok for panel work, etc., but, I believe the spec indicate that it should be holding a tighter regulation.
Any thoughts on what maybe going on...?
David
PS: ...voltage measurement being done with a cheap digital DVM and I do not know if the switching power supply would cause errors that I have not considered.....
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nuckolls.bob(at)aeroelect Guest
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Posted: Thu Sep 15, 2011 5:54 am Post subject: Report on New Power Supply |
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At 06:49 PM 9/14/2011, you wrote:
Hi Bob,
Several months ago I too purchased one of these units (or similar) as
it seemed like a great method to power up the panel when working on
the electrical problems, changes, etc. Rated at 13.5 v., 350W, the
first unit I received (they come from China) would not hold voltage
when loaded with about 5-6 amps of panel load. It started at about
13.4 v. and dropped to 12.4 when the panel was powered up. I
contacted the seller and he said to return it and he would replace it.
I did and about 4 wks later he sent me a replacement. It is
functioning in a similar fashion. No load about 13.4 and mild load
drops to 12.75. Still Ok for panel work, etc., but, I believe the
spec indicate that it should be holding a tighter regulation.
Any thoughts on what maybe going on...?
You got me my friend. I've had first-hand contact with
four power supplies from the source I linked. Two are
already out the door, two more are waiting installation in a
project. I just went to the bench and hooked up one
out of the box. It was set for 13.5 zero load. Put
a 1.0 ohm resistor across it (13.5A) and got maybe
0.05 volts drop.
David
PS: ...voltage measurement being done with a cheap digital DVM and I
do not know if the switching power supply would cause errors that I
have not considered.....
I wouldn't think so . . . but there IS a reason for
what you have observed. The mission is to figure out
what it is. Cross checking with another instrument
is a good first step.
Forgive the potential for insult by asking whether you've
accounted for wire drops? The test I just made measured
voltage right at the V+ and V- terminals on the supply.
The 1 ohm resistor was connected to adjacent V+ and
V- terminals.
A tech at HBC built what he thought was a handy
load tester where his power resistor was in a nice
box that plugged onto the front of his multimeter.
The test leads plugged into the front of his load
box. Of course, the meter was making measurements
a the ends of test leads while loaded with significant
current.
Like the 4-wire low-ohms adapter, an accurate
high-loads adapter begs for the same 4-wire
measurement where the instrument and load paths
are not shared. We modified his box to add separate
banana jacks for load and measurement and subsequent
measurements were much more meaningful.
Bob . . .
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nuckolls.bob(at)aeroelect Guest
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Posted: Sat Sep 24, 2011 5:55 pm Post subject: Report on New Power Supply |
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At 06:49 PM 9/14/2011, you wrote:
Quote: | Hi Bob,
Several months ago I too purchased one of these units (or similar) as it seemed like a great method to power up the panel when working on the electrical problems, changes, etc. Rated at 13.5 v., 350W, the first unit I received (they come from China) would not hold voltage when loaded with about 5-6 amps of panel load. It started at about 13.4 v. and dropped to 12.4 when the panel was powered up. <snip> |
Dave, did you run the reasons for your observations
to ground?
Bob . . . [quote][b]
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skywagon
Joined: 11 Feb 2006 Posts: 184
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Posted: Sun Sep 25, 2011 6:45 am Post subject: Report on New Power Supply |
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Bob,
...I am on an extended trip with limited email, etc.
No, I have not run further tests nor tried anything to find the reason for poor regulation on the power supply.
....more later, David
______________________________________________________
On Sat, Sep 24, 2011 at 6:51 PM, Robert L. Nuckolls, III wrote:
At 06:49 PM 9/14/2011, you wrote:
Hi Bob,
Several months ago I too purchased one of these units (or similar) as it seemed like a great method to power up the panel when working on the electrical problems, changes, etc. Rated at 13.5 v., 350W, the first unit I received (they come from China) would not hold voltage when loaded with about 5-6 amps of panel load. It started at about 13.4 v. and dropped to 12.4 when the panel was powered up. <snip>
Dave, did you run the reasons for your observations
to ground?
Bob . . .
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