<html><body><div style="color:#000; background-color:#fff; font-family:arial, helvetica, sans-serif;font-size:12pt"><div style="RIGHT: auto"><SPAN style="RIGHT: auto">I am both interested in the idle power, and the operating efficiency<BR style="RIGHT: auto" class=yui-cursor></SPAN></div>
<div style="RIGHT: auto">This often comes up, but what does it require to allow a DC appliance to wait and simply turn on when when necessary and not waste power when it is off? </div>
<div style="RIGHT: auto">Darryl<VAR id=yui-ie-cursor></VAR><BR style="RIGHT: auto"></div>
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<DIV style="BORDER-BOTTOM: #ccc 1px solid; BORDER-LEFT: #ccc 1px solid; PADDING-BOTTOM: 0px; LINE-HEIGHT: 0; MARGIN: 5px 0px; PADDING-LEFT: 0px; PADDING-RIGHT: 0px; HEIGHT: 0px; FONT-SIZE: 0px; BORDER-TOP: #ccc 1px solid; BORDER-RIGHT: #ccc 1px solid; PADDING-TOP: 0px" class=hr contentEditable=false readonly="true"></DIV><B><SPAN style="FONT-WEIGHT: bold">From:</SPAN></B> Exeltech <exeltech@yahoo.com><BR><B><SPAN style="FONT-WEIGHT: bold">To:</SPAN></B> RE-wrenches <re-wrenches@lists.re-wrenches.org><BR><B><SPAN style="FONT-WEIGHT: bold">Sent:</SPAN></B> Thursday, September 1, 2011 3:30 PM<BR><B><SPAN style="FONT-WEIGHT: bold">Subject:</SPAN></B> Re: [RE-wrenches] unique battery bank design question<BR></FONT><WBR>
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<TD vAlign=top>Hi Jason,<BR><BR>Well designed off-the-shelf converters can achieve 90% efficiency, and as you mention, this will vary a bit depending on the rated output current of the converter vs. the actual load current.<BR><BR>I've designed and built 24V @ 25A to 12V @ 50A converters for my own use that are in the 95% realm.<BR><BR>Your mileage may vary.<BR><BR>Dan<BR><BR><BR>--- On <B>Thu, 9/1/11, Jason Szumlanski <I><Jason@fafcosolar.com></I></B> wrote:<BR>
<BLOCKQUOTE style="BORDER-LEFT: rgb(16,16,255) 2px solid; PADDING-LEFT: 5px; MARGIN-LEFT: 5px"><BR>From: Jason Szumlanski <Jason@fafcosolar.com><BR>Subject: Re: [RE-wrenches] unique battery bank design question<BR>To: "RE-wrenches" <re-wrenches@lists.re-wrenches.org><BR>Date: Thursday, September 1, 2011, 3:07 PM<BR><BR>
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<div class=yiv1839468312MsoNormal><SPAN style="COLOR: rgb(31,73,125); FONT-SIZE: 11pt">Dan,</SPAN></div>
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<div class=yiv1839468312MsoNormal><SPAN style="COLOR: rgb(31,73,125); FONT-SIZE: 11pt">What kind of efficiency level (%) can you get out of a DC-DC supply on a small load, say <5A @ 12V with a 48V->12V converter? Is the efficiency level highly variable depending on load as a percentage of the converter’s maximum capacity, or is it pretty constant?</SPAN></div>
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<div class=yiv1839468312MsoNormal><SPAN style="COLOR: rgb(31,73,125); FONT-SIZE: 11pt">I run into this once in a while, so this piece of information would help me make some better decisions.</SPAN></div>
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<div class=yiv1839468312MsoNormal><SPAN style="COLOR: rgb(31,73,125); FONT-SIZE: 11pt">Thanks,</SPAN></div>
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<div class=yiv1839468312MsoNormal><SPAN style="COLOR: rgb(31,73,125)">Jason Szumlanski</SPAN></div>
<div class=yiv1839468312MsoNormal><SPAN style="COLOR: rgb(31,73,125); FONT-SIZE: 11pt">Fafco Solar</SPAN><SPAN style="COLOR: rgb(31,73,125); FONT-SIZE: 4pt"> </SPAN></div>
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