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<DIV><FONT size=2 face=Arial>I forgot to include the reference for PV
battery charging without a charge controller. It is 'Solar Photovoltaic
Applications Seminar: Design, Installation and Operation of Small, Stand-Alone
Photovoltaic Power Systems,' July 1980, 351 pages, DOE/CS/32522-T1</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>"Direct electrical connection of the array to the
battery system without regulation is advisable only when the peak output current
of the array is less than 5% of the charge capacity of the batteries (amp-hour
rating) in the system (charge equals current x time)." </FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>This document is one of the first
comprehensive PV system design books and well worth reading. I
could not find it for free on the internet. Jim Fortenberry at Jet
Propulsion Laboratory gave me his copy in 1986 when the Reagan
Administration stopped the JPL solar program and Block V testing the
same year UL 1703 was published.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Joel Davidson</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
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style="BORDER-LEFT: #000000 2px solid; PADDING-LEFT: 5px; PADDING-RIGHT: 0px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="FONT: 10pt arial; BACKGROUND: #e4e4e4; font-color: black"><B>From:</B>
<A title=bob-o@electronconnection.com
href="mailto:bob-o@electronconnection.com">Bob-O Schultze</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> Sunday, March 28, 2010 9:18
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> [RE-wrenches] NABCEP Exam was:
PV excellent battery charger</DIV>
<DIV><BR></DIV>Folks,
<DIV>While none of us obviously has access to the wording of the specific
question itself, I can assure you that there are no "tricky" or non-sensical
questions on ANY of the NABCEP exams. Our Subject Matter Experts (SMEs) who
come up with the questions AND the answers aren't a bunch of nerds in a
university somewhere, they are us; working wrenches like ourselves. All the
questions and answered are submitted to a round table discussion of the SMEs
to be accepted, modified to be made clearer, or thrown out. At the same time,
they are reviewed by a professional testing expert for clarity, readability,
and correct usage of the language. Of the four answer choices, there are
almost always two which are dead wrong, one which could be arrived at if you
didn't follow all the steps of the question or didn't exactly know the
material, and the correct answer. If you think all that is easy to do, try it
sometime.</DIV>
<DIV>After the test is taken, the testing expert analyses the raw data and the
SMEs review any items which seem questionable. For example, if most of the
test takers INCLUDING those who did very well on the test otherwise missed a
certain question, they take a hard look at it to see if there is ambiguity or
if it can be interpreted differently from the way it was intended. It does
happen that in spite of all the work put into developing the question, it is
flawed in some way. When that happens, the question is discarded and all the
test takers in that round get credit for it.</DIV>
<DIV>As to putting together a study guide, that's even harder. Remember that
it's a "Guide", not a book like the NEC wherein lie all the answers to the
questions. The Entry Level test is not a snap by any means, but it is basic in
nature to our field and there are no questions on it that an installer would
have to face, IE, anything to do with the NEC. The Installer Certification
test is difficult, as it should be. Unless you know our trade inside and out
PLUS have done some study in the areas which you don't do at all or very often
(we all have those), you will have difficulty in achieving a passing score. I
know many good Wrenches who missed it at least the first time. Some of those
just say, "Screw it, I don't need this shit". Others have challenged
themselves to hit the books again and brush up on the areas they found out
(from taking the test the first time) where they were weak and nailed it on
the next round. Everyone I've ever talked to, including myself, has said that
they are a better craftsperson for having taken and passed the test.</DIV>
<DIV>Bob-O</DIV>
<DIV><BR></DIV>
<DIV><BR></DIV>
<DIV>
<DIV>
<DIV>On Mar 27, 2010, at 8:02 PM, Darryl Thayer wrote:</DIV><BR
class=Apple-interchange-newline>
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<TR>
<TD vAlign=top>I have never seen the exam but I have been told several
of the questions are nonsense. Just like the study guide,
and from what I hear there are questions of
similar nature on the installers exam. Something is wrong
with the test generation. <BR>Darryl<BR><BR>--- On <B>Sat,
3/27/10, Warren Lauzon <I><<A
href="mailto:windsun@wind-sun.com">windsun@wind-sun.com</A>></I></B>
wrote:<BR>
<BLOCKQUOTE
style="Z-INDEX: auto; POSITION: static; BORDER-LEFT: rgb(16,16,255) 2px solid; PADDING-LEFT: 5px; MARGIN-LEFT: 5px"><BR>From:
Warren Lauzon <<A
href="mailto:windsun@wind-sun.com">windsun@wind-sun.com</A>><BR>Subject:
Re: [RE-wrenches] PV excellent battery charger<BR>To: "RE-wrenches"
<<A
href="mailto:re-wrenches@lists.re-wrenches.org">re-wrenches@lists.re-wrenches.org</A>><BR>Date:
Saturday, March 27, 2010, 10:55 AM<BR><BR>
<DIV id=yiv759174826>
<STYLE></STYLE>
<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/"
rel=nofollow
target=_blank>http://www.wind-sun.com/ForumVB/</A><BR>..................................................................................................</DIV>
<BLOCKQUOTE
style="Z-INDEX: auto; POSITION: static; BORDER-LEFT: rgb(0,0,0) 2px solid; PADDING-LEFT: 5px; PADDING-RIGHT: 0px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px">
<DIV
style="FONT: 10pt arial; font-size-adjust: none; font-stretch: normal">-----
Original Message ----- </DIV>
<DIV
style="FONT: 10pt arial; BACKGROUND: rgb(228,228,228) 0% 50%; font-size-adjust: none; font-stretch: normal; -moz-background-clip: -moz-initial; -moz-background-origin: -moz-initial; -moz-background-inline-policy: -moz-initial"><B>From:</B>
<A title=drake.chamberlin@redwoodalliance.org
href="x-msg://27/mc/compose?to=drake.chamberlin@redwoodalliance.org"
rel=nofollow target=_blank
ymailto="mailto:drake.chamberlin@redwoodalliance.org">Drake
Chamberlin</A> </DIV>
<DIV
style="FONT: 10pt arial; font-size-adjust: none; font-stretch: normal"><B>To:</B>
<A title=re-wrenches@lists.re-wrenches.org
href="x-msg://27/mc/compose?to=re-wrenches@lists.re-wrenches.org"
rel=nofollow target=_blank
ymailto="mailto:re-wrenches@lists.re-wrenches.org">RE-wrenches</A>
</DIV>
<DIV
style="FONT: 10pt arial; font-size-adjust: none; font-stretch: normal"><B>Sent:</B>
Saturday, March 27, 2010 9:28 AM</DIV>
<DIV
style="FONT: 10pt arial; font-size-adjust: none; font-stretch: normal"><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>
<P><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>
<DIV><BR class=webkit-block-placeholder></DIV>
<HR>
<DIV><BR
class=webkit-block-placeholder></DIV>_____________</BLOCKQUOTE></DIV></BLOCKQUOTE></TD></TR></TBODY></TABLE></DIV><BR></DIV>
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