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<DIV>Jeff,</DIV>
<DIV>My experience with LED lighting is limited, but in the systems I have done
I included a DC-DC voltage regulator as the voltage range was +/- 10%. Had no
issues with manufacturer (since gone out of business - ouch). The
system has worked fine for going on 6 years.</DIV>
<DIV> </DIV>
<DIV>Holt E. Kelly<BR>Holtek Fireplace & Solar Products<BR>500 Jewell
Dr.<BR>Waco TX. 76712<BR>254-751-9111<BR><A
href="http://www.holteksolar.com">www.holteksolar.com</A><BR></DIV>
<BLOCKQUOTE
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=jryago@dtisolar.com href="mailto:jryago@dtisolar.com">Jeff Yago</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=conradg@cape.com
href="mailto:conradg@cape.com">conradg@cape.com</A> ; <A
title=re-wrenches@lists.re-wrenches.org
href="mailto:re-wrenches@lists.re-wrenches.org">'RE-wrenches'</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Friday, December 16, 2011 12:24
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [RE-wrenches] DC power for
LED lighting</DIV>
<DIV><BR></DIV>
<DIV class=WordSection1>
<P class=MsoNormal><SPAN
style="FONT-SIZE: 11pt; COLOR: #1f497d; FONT-FAMILY: 'Calibri','sans-serif'">I
have a local sign company that asked is to provide a solar lighting system for
a double sided sign they were building for a large retirement community
entrance. We have provided many solar lighting systems just like this
over the years and sent them several examples. All our systems have been
turn-key in that we provided the 12 VDC ground mounted LED flood lights with
the separately pole mounted solar module(S) and battery/controller
box. We “assumed” when we told them our system includes the LED
lights that they understood that we were providing the lighting.
<o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-SIZE: 11pt; COLOR: #1f497d; FONT-FAMILY: 'Calibri','sans-serif'"><o:p> </o:p></SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-SIZE: 11pt; COLOR: #1f497d; FONT-FAMILY: 'Calibri','sans-serif'">Unfortunately,
when we arrived on the site to install the solar system, they said they did
not need our LED lights, they wanted us to power the LED lights inside the
sign. We opened up the signs and found two 120 VAC electronic LED power
supplies. Each was clearly labeled as providing a maximum of 5 amps at
12 VDC output, and each powered a separate string of about 150 tiny plastic
“blocks” and each block contained 2 small LED lamps. We
immediately advised the client that the solar system was designed to
power our two 12 VDC flood lights and we would have to totally tear out
what we had just installed and go to a much larger system that included an
inverter, larger array, 120 VAC timing device, and replace the 2 conductor DC
underground wiring with 3-conductor AC wire and all this would
really increase $$$.<o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-SIZE: 11pt; COLOR: #1f497d; FONT-FAMILY: 'Calibri','sans-serif'"><o:p> </o:p></SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-SIZE: 11pt; COLOR: #1f497d; FONT-FAMILY: 'Calibri','sans-serif'">I
said as an alternative, why can’t we just cut out the two electronic120 VAC
input LED drivers since we are providing well regulated 12 VDC power
direct from the GEL battery. He checked with their LED lamp
supplier and they said they strongly disagree and will void warranty.
Since we are talking about almost 300 total LED devices my client is afraid to
give us the OK, even though we did run them overnight and everything worked
just fine. As I recall, an LED needs something in the circuit to
limit the amp current, not the voltage flowing through it, or it will
just get brighter and brighter and then fail. However, I thought almost
all strings of separate LED lights already had some kind of regulator built
into each light block otherwise those near the end of the string would be less
bright than those near the power source. Is this
correct??<o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-SIZE: 11pt; COLOR: #1f497d; FONT-FAMILY: 'Calibri','sans-serif'"><o:p> </o:p></SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-SIZE: 11pt; COLOR: #1f497d; FONT-FAMILY: 'Calibri','sans-serif'">Finally,
if strings of LEDs require some kind of voltage or current regulator, I can’t
believe they all have to run on 120 VAC as indicated by this LED manufacturer
who offers no alternative. Any LED experts out there that
can point me to some type of DC-to-DC converter or current regulator
that can replace these 120VAC LED drivers?<o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-SIZE: 11pt; COLOR: #1f497d; FONT-FAMILY: 'Calibri','sans-serif'"><o:p> </o:p></SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-SIZE: 11pt; COLOR: #1f497d; FONT-FAMILY: 'Calibri','sans-serif'">Thanks,<o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-SIZE: 11pt; COLOR: #1f497d; FONT-FAMILY: 'Calibri','sans-serif'"><o:p> </o:p></SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-SIZE: 11pt; COLOR: #1f497d; FONT-FAMILY: 'Calibri','sans-serif'">Jeff
Yago<o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-SIZE: 11pt; COLOR: #1f497d; FONT-FAMILY: 'Calibri','sans-serif'"><o:p> </o:p></SPAN></P></DIV>
<P>
<HR>
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