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<div class="moz-cite-prefix">Brian,<br>
Re:<span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">
Do you know what the daily Ah consumption is, or alternatively
what the daily DOD is on the batteries?:</span> We don't have
that data. The home has an E-Meter, but the programming settings
were far enough off that I wouldn't trust the historic data. Also,
Eden has memorized TriMetric (and more modern datalogging)
operation, but I realize that there are so few E-Meters still in
use that he doesn't know how to extract avg. DOD and other
historic data from one of these relics. The C60 has no DVM, so
there's no input data. This is not uncommon around here, where
people have lived with funky off grid systems since the earliest
days.<br>
<br>
The home has a Frigidaire conventional refrigerator of unknown
vintage and efficiency, so it's safe to assume that the batteries
seldom are full. As a rule of thumb, I generally tell clients that
a kilowatt of array is pretty much the minimum to run an off grid
home with a carefully-selected AC refrigerator (and we neither
recommend Sun Frost or LP refrigerators). <br>
<br>
The array includes a couple of 102W Evergreens, a couple of 100W
Photowatts, a 103W Sharp, and even a set of 5V Carrizo Tri-Lam
SuperGolds (105W estimate when "new"), so it's reasonable to
suspect that age and incompatibility will reduce the output from
48A. The measured input yesterday, which was hot, was 35A in in
late morning, a C/25 rate with nothing on at the time.<br>
<br>
I just spoke with Dave, senior tech support at Concorde. 1) These
four year old batteries are already likely already shot from
chronic undercharge. 2) We could run at bulk all day with this
array and never get them full. 3) The batteries begin to recombine
at around 13.5V, which depending on current causes enough pressure
to cause release of gasses, as the caps are rated at 2.5 psi, so
4) If we tripled the array it would still not fill them, but then
we would want to set float voltage at float range of around
13.1-13.2 V. 5) The C60 with its one-hour absorption is a poor
match, and 6) the whole system should be torn out and replaced. <br>
<br>
In short, we can't solve her problems, but yes, as it is now set
up we could set the float voltage to be the same as the bulk
voltage and still not get the batteries full.<br>
<br>
Thank you,<br>
Allan<br>
<br>
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<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>
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</div>
On 8/1/2013 4:27 PM, Brian Teitelbaum wrote:<br>
</div>
<blockquote
cite="mid:8961DF9D3453CF41A4A5B6E6BECA4C7722CFB8D1C4@VS-SJEXCH01.recsolar.local"
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<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Allan,<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Do
you know what the daily Ah consumption is, or alternatively
what the daily DOD is on the batteries?<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">830W
of PV on a PWM controller should have a peak amperage of
about 48A (830W ÷ 17Vmp = 48.82A). This is only about a C/18
charge rate, which is fairly low but should be workable as
long as solar production keeps up with load demand. Of
course, with old modules you may not see that many amps,
especially in hot weather.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">If
they don’t have an amp-hour meter installed, that should be
an upgrade priority. Every off-grid system should have an
amp-hour meter, especially a rental house.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Without
some DOD battery info it’s hard to tell exactly what’s going
on, but I think that as long as some energy is consumed each
night I don’t see any reason why you couldn’t set the float
voltage the same as the bulk/absorption voltage, at least in
this case. The charging day is limited to hours of sunlight,
and as long as you stay under the gassing voltage it should
be fine. But as Eric Benson noted, the battery manufacturer
should have the final word.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Brian
Teitelbaum<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">AEE
Solar<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<div>
<div style="border:none;border-top:solid #B5C4DF
1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext">From:</span></b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext">
<a class="moz-txt-link-abbreviated" href="mailto:re-wrenches-bounces@lists.re-wrenches.org">re-wrenches-bounces@lists.re-wrenches.org</a>
[<a class="moz-txt-link-freetext" href="mailto:re-wrenches-bounces@lists.re-wrenches.org">mailto:re-wrenches-bounces@lists.re-wrenches.org</a>] <b>On
Behalf Of </b>Allan Sindelar<br>
<b>Sent:</b> Thursday, August 01, 2013 1:20 PM<br>
<b>To:</b> RE-wrenches<br>
<b>Subject:</b> [RE-wrenches] C60 setpoint question<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal" style="margin-bottom:12.0pt">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<o:p></o:p></p>
<div>
<p class="MsoNormal">-- <br>
<br>
<o:p></o:p></p>
<p class="MsoNormal"><b>Allan Sindelar</b><br>
<span style="font-size:10.0pt"><a moz-do-not-send="true"
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 Corporation</span><sup><span
style="font-size:7.5pt">TM</span></sup><span
style="font-size:10.0pt"><br>
3209 Richards Lane<br>
Santa Fe, New Mexico 87507<br>
<b>505 424-1112 office 780-2738 cell</b><br>
<a moz-do-not-send="true"
href="http://www.positiveenergysolar.com/"
target="_blank"><u>www.positiveenergysolar.com</u></a></span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:10.0pt"> </span><o:p></o:p></p>
</div>
</div>
</blockquote>
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