<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=ISO-8859-1">
</head>
<body text="#000000" bgcolor="#FFFFFF">
Wrenches,<br>
Eden, our main off grid field tech, came across a situation about
which I want to ask the group for advice, please.<br>
<br>
The system: existing old/funky off grid 12V residential system, done
by others over many years; this was our first visit. Owner out of
state, currently rented, owner's complaint is that the old Heart
2800 EMS inverter is shutting down at times. Six four year old
Concorde SunXtender PVX-3050Ts, so 900 rated amp-hours in three
strings at 12V. Approximately 830 watts of a hodgepodge of older
modules, but well below rated output at present, though no obvious
failures. Trace C60 charge controller. Our assessment after a site
visit is that the batteries have been chronically undercharged and
are showing signs of premature sulfation.<br>
<br>
With AGM batteries such as these, we have been encouraged (by
Midnite tech support and others) to set really long absorption times
- we have some systems with six-hour absorptions. The logic is that
theese batteries can tolerate - indeed thrive on - staying at
absorption voltage of 14.2 - 14.4 V (for 12 V nominal) indefinitely,
and given the fickle nature of off grid PV charging, this maximizes
the likelihood of their getting full most days. This logic makes
total sense to me.<br>
<br>
Most modern MPPT charge controllers have a programmable absorption
time, and some have a done amps (a.k.a. float transition current),
to allow them to transition to float if the charge current necessary
to maintain absorption voltage drops below a set threshold
(typically 1-3% of battery capacity). The C60 has neither, but
rather has a nonadjustable two-hour timed absorption. This brings
the question: is there any good reason that the float voltage on the
C60 should not be set to the same voltage as the bulk/absorption
voltage, such that they never drop into float? When sufficient input
is available to get the batteries full, they are just allowed to
stay in absorption mode indefinitely, slowly getting the energy
necessary to reach 100%.<br>
<br>
We have installed many Concorde AGM batteries, but never with an old
C-series controller. This idea seems wacky, but the more I think
about it, the more I can't see any problem with it. What do the rest
of you advise?<br>
Thanks, Allan<br>
<br>
<div class="moz-signature">-- <br>
<meta http-equiv="Content-Type" content="text/html;
charset=ISO-8859-1">
<meta name="ProgId" content="Word.Document">
<meta name="Generator" content="Microsoft Word 11">
<meta name="Originator" content="Microsoft Word 11">
<link rel="File-List" href="SignatureNew_files/filelist.xml">
<!--[if gte mso 9]><xml>
<o:DocumentProperties>
<o:Author>pe</o:Author>
<o:Template>Normal</o:Template>
<o:LastAuthor>pe</o:LastAuthor>
<o:Revision>5</o:Revision>
<o:TotalTime>1</o:TotalTime>
<o:Created>2013-06-07T19:15:00Z</o:Created>
<o:LastSaved>2013-06-10T19:03:00Z</o:LastSaved>
<o:Pages>1</o:Pages>
<o:Words>73</o:Words>
<o:Characters>420</o:Characters>
<o:Company>pe</o:Company>
<o:Lines>3</o:Lines>
<o:Paragraphs>1</o:Paragraphs>
<o:CharactersWithSpaces>492</o:CharactersWithSpaces>
<o:Version>11.9999</o:Version>
</o:DocumentProperties>
</xml><![endif]--><!--[if gte mso 9]><xml>
<w:WordDocument>
<w:SpellingState>Clean</w:SpellingState>
<w:GrammarState>Clean</w:GrammarState>
<w:ValidateAgainstSchemas/>
<w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid>
<w:IgnoreMixedContent>false</w:IgnoreMixedContent>
<w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText>
<w:Compatibility>
<w:UseFELayout/>
</w:Compatibility>
<w:BrowserLevel>MicrosoftInternetExplorer4</w:BrowserLevel>
</w:WordDocument>
</xml><![endif]--><!--[if gte mso 9]><xml>
<w:LatentStyles DefLockedState="false" LatentStyleCount="156">
</w:LatentStyles>
</xml><![endif]-->
<style>
<!--
/* Font Definitions */
@font-face
{font-family:"MS Mincho";
panose-1:2 2 6 9 4 2 5 8 3 4;
mso-font-alt:"\FF2D\FF33 \660E\671D";
mso-font-charset:128;
mso-generic-font-family:modern;
mso-font-pitch:fixed;
mso-font-signature:-1610612033 1757936891 16 0 131231 0;}
@font-face
{font-family:"\@MS Mincho";
panose-1:2 2 6 9 4 2 5 8 3 4;
mso-font-charset:128;
mso-generic-font-family:modern;
mso-font-pitch:fixed;
mso-font-signature:-1610612033 1757936891 16 0 131231 0;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{mso-style-parent:"";
margin:0in;
margin-bottom:.0001pt;
mso-pagination:widow-orphan;
font-size:12.0pt;
font-family:"Times New Roman";
mso-fareast-font-family:"MS Mincho";
color:black;}
a:link, span.MsoHyperlink
{color:blue;}
a:visited, span.MsoHyperlinkFollowed
{color:blue;}
span.SpellE
{mso-style-name:"";
mso-spl-e:yes;}
@page Section1
{size:8.5in 11.0in;
margin:1.0in 1.25in 1.0in 1.25in;
mso-header-margin:.5in;
mso-footer-margin:.5in;
mso-paper-source:0;}
div.Section1
{page:Section1;}
-->
</style><!--[if gte mso 10]>
<style>
/* Style Definitions */
table.MsoNormalTable
{mso-style-name:"Table Normal";
mso-tstyle-rowband-size:0;
mso-tstyle-colband-size:0;
mso-style-noshow:yes;
mso-style-parent:"";
mso-padding-alt:0in 5.4pt 0in 5.4pt;
mso-para-margin:0in;
mso-para-margin-bottom:.0001pt;
mso-pagination:widow-orphan;
font-size:10.0pt;
font-family:"Times New Roman";
mso-fareast-font-family:"Times New Roman";
mso-ansi-language:#0400;
mso-fareast-language:#0400;
mso-bidi-language:#0400;}
</style>
<![endif]--><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="4098"/>
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1"/>
</o:shapelayout></xml><![endif]-->
<div class="Section1">
<p class="MsoNormal"><b>Allan <span class="SpellE">Sindelar</span></b><br>
<span style="font-size:10.0pt"><a
href="mailto:Allan@positiveenergysolar.com"><u><span
style="color:#000099">Allan@positiveenergysolar.com</span></u></a></span><br>
<span style="font-size:10.0pt">NABCEP Certified PV
Installation Professional <br>
NABCEP Certified Technical Sales Professional<br>
New Mexico EE98J Journeyman Electrician<br>
Founder and Chief Technology Officer<br>
<b>Positive Energy, Inc.</b>, a Certified B <span
class="SpellE">Corporation<sup><span
style="font-size:7.5pt">TM</span></sup></span><br>
3209 Richards Lane<br>
Santa Fe, New Mexico 87507<br>
<b>505 424-1112 office 780-2738 cell</b><br>
<a href="http://www.positiveenergysolar.com/"
target="_blank"><u>www.positiveenergysolar.com</u></a><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt"><span
style="mso-spacerun:yes"> </span></span></p>
</div>
</div>
</body>
</html>