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<DIV><FONT size=2 face=Calibri>To be honest, I don't think the question makes
any sense. There are several "right" answers, but no good ones. I hope that is
not the extent of the battery questions on that exam.</FONT></DIV>
<DIV><FONT size=2 face=Calibri></FONT> </DIV>
<DIV>..................................................................................................<BR>Northern
Arizona Wind & Sun - Electricity From The Sun Since 1979<BR>Solar Discussion
Forum: <A
href="http://www.wind-sun.com/ForumVB/">http://www.wind-sun.com/ForumVB/</A><BR>..................................................................................................</DIV>
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<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="FONT: 10pt arial; BACKGROUND: #e4e4e4; font-color: black"><B>From:</B>
<A title=drake.chamberlin@redwoodalliance.org
href="mailto:drake.chamberlin@redwoodalliance.org">Drake Chamberlin</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <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> Saturday, March 27, 2010 9:28
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [RE-wrenches] PV excellent
battery charger</DIV>
<DIV><BR></DIV>Hi Dave, <BR><BR>At 10:44 AM 3/26/2010, you wrote:<BR>
<BLOCKQUOTE class=cite cite="" type="cite">Is the answer here (at least the
one that NABCEP intends) just that the VMP of a "12V module" is higher than
the voltage of a 12V battery? With the higher voltage it will charge the
battery with its corresponding current based on the I-V curve. The objective
reads "Explain why PV modules make excellent battery chargers based on their
I-V characteristics</BLOCKQUOTE><BR><BR>This may be the answer they
want. The "Objectives" deals with the 5 key points on the IV curve, Vmp,
Imp, Voc, Isc and Pmp. >From a study of the curve, the obvious
"excellent" load is one that takes power from Pmp, which direct battery
charging doesn't do. When I draw the curve, the Vmp of the module is
above the resulting voltage on the curve. <BR><BR>What you say about the
power loss not being released as heat in the batteries, just not
produced, makes sense to me. I've never seen any real documentation
about what happens to the power not gained in a non MPPT battery charging
system. <BR><BR>We can definitely agree that "excellent battery charger" is an
exaggeration. <BR><BR>Thanks,<BR><BR>Drake <BR><BR><X-SIGSEP>
<P></X-SIGSEP><FONT color=#0000ff>Drake Chamberlin<BR>Athens Electric<BR>OH
License 44810<BR>CO License 3773<BR>NABCEP </FONT><FONT color=#0000ff
size=1>TM </FONT><FONT color=#0000ff>Certified PV Installer <BR>Office -
740-448-7328<BR>Mobile - 740-856-9648 </FONT>
<P>
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