<table cellspacing="0" cellpadding="0" border="0" ><tr><td valign="top" style="font: inherit;">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: 2px solid rgb(16, 16, 255); margin-left: 5px; padding-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><div id="yiv259713687"><style><!--
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--></style><div class="yiv259713687WordSection1"><p class="yiv259713687MsoNormal"><span style="font-size: 11pt; font-family: "sans-serif"; color: rgb(31, 73, 125);">Dan,</span></p><p class="yiv259713687MsoNormal"><span style="font-size: 11pt; font-family: "sans-serif"; color: rgb(31, 73, 125);"> </span></p><p class="yiv259713687MsoNormal"><span style="font-size: 11pt; font-family: "sans-serif"; color: rgb(31, 73, 125);">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></p><p class="yiv259713687MsoNormal"><span style="font-size: 11pt; font-family: "sans-serif"; color: rgb(31, 73, 125);"> </span></p><p class="yiv259713687MsoNormal"><span style="font-size: 11pt; font-family:
"sans-serif"; color: rgb(31, 73, 125);">I run into this once in a while, so this piece of information would help me make some better decisions.</span></p><p class="yiv259713687MsoNormal"><span style="font-size: 11pt; font-family: "sans-serif"; color: rgb(31, 73, 125);"> </span></p><p class="yiv259713687MsoNormal"><span style="font-size: 11pt; font-family: "sans-serif"; color: rgb(31, 73, 125);">Thanks,</span></p><p class="yiv259713687MsoNormal"><span style="font-size: 11pt; font-family: "sans-serif"; color: rgb(31, 73, 125);"> </span></p><p class="yiv259713687MsoNormal"><span style="font-family: "sans-serif"; color: rgb(31, 73, 125);">Jason Szumlanski</span></p><p class="yiv259713687MsoNormal"><span style="font-size: 11pt; font-family: "sans-serif"; color: rgb(31, 73, 125);">Fafco Solar</span><span style="font-size: 4pt; font-family: "sans-serif"; color: rgb(31, 73,
125);"> </span></p><p class="yiv259713687MsoNormal"><span style="font-size: 11pt; font-family: "sans-serif"; color: rgb(31, 73, 125);"><br> </span></p><p class="yiv259713687MsoNormal"><span style="font-size: 11pt; font-family: "sans-serif"; color: rgb(31, 73, 125);"> </span></p></div></div><div class="plainMail"><br></div></blockquote></td></tr></table>