<div dir="ltr">Hello Wrenches,<div><br></div><div>I have been following this C-40 drifting thread. From my personal experience the C-40 always had about a 0.2 to 0.4 volt drift since the early days (1994-95). This was on a 48-volt system, so the drift might be less at lower battery voltages. The drift was not a simple mis-calibration; one day 0.3 volt high, another day 0.4 volts low.</div><div>I don't know if this is a component of the problem, but thought I would mention it.</div><div><br></div><div>Best Regards,</div><div><br></div><div>Steve Bell</div><div> <br><div><br></div><div><br></div></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Wed, May 20, 2015 at 7:34 PM, <span dir="ltr"><<a href="mailto:Jarmo.Venalainen@schneider-electric.com" target="_blank">Jarmo.Venalainen@schneider-electric.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><font size="2" face="sans-serif">Hi:</font>
<br>
<br><font size="2" face="sans-serif">My thought is that the mechanism by
which the battery voltage slowly rises under the influence of a solar module
connected through a C40 type PWM controller is due to the fact that the
PWM type controllers don't regulate voltage but rather connect the full
output voltage of the module/array to the battery on a pulse width limited
basis.</font>
<br>
<br><font size="2" face="sans-serif">Seems that those high voltage pulses,
brief as they may be thanks to the PWM, are still none the less able to
slowly raise the resting terminal voltage of at least some types of AGM
batteries.</font>
<br>
<br><font size="2" face="sans-serif">I don't know enough about batteries
to know if that is a problem or not. Perhaps its perfectly normal
as almost any new lead acid battery will retain a higher than normal measurable
"ghost voltage" just after it has been fully charged.</font>
<br><span class="">
<br><font size="2" face="sans-serif">JARMO</font>
<br>
<br><font size="2" face="sans-serif"><br>
</font><font size="3" color="#008000">_____________________________________________________________________________________</font><font size="3">
<br>
</font><font size="1" face="Arial"><b><br>
Jarmo Venalainen</b> | </font><font size="1" color="#008000" face="Arial"><b>
Schneider Electric </b></font><font size="1" face="Arial"><b> | Xantrex
Brand</b> | <b>CANADA</b> | <b>Sales Application
Engineer</b> <b><br>
Phone:</b> <a href="tel:%2B604-422-2528" value="+6044222528" target="_blank">+604-422-2528</a> | <b>Tech Support:</b> <a href="tel:800-670-0707" value="+18006700707" target="_blank">800-670-0707</a>
| <b>Mobile:</b> <a href="tel:%2B604-505-0291" value="+6045050291" target="_blank">+604-505-0291</a> <b><br>
Email:</b> </font><a href="mailto:jarmo.venalainen@schneider-electric.com" target="_blank"><font size="1" color="blue" face="Arial"><u>jarmo.venalainen@schneider-electric.com</u></font></a><font size="1" face="Arial">
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<b>Address:</b> 3700 Gilmore Way, Burnaby, BC V5G4M1 <br>
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<td><font size="1" color="#5f5f5f" face="sans-serif">From:</font>
</td><td><font size="1" face="sans-serif">Drake <<a href="mailto:drake.chamberlin@redwoodalliance.org" target="_blank">drake.chamberlin@redwoodalliance.org</a>></font>
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<td><font size="1" color="#5f5f5f" face="sans-serif">To:</font>
</td><td><font size="1" face="sans-serif">RE-wrenches <<a href="mailto:re-wrenches@lists.re-wrenches.org" target="_blank">re-wrenches@lists.re-wrenches.org</a>>,
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<td><font size="1" color="#5f5f5f" face="sans-serif">Date:</font>
</td><td><font size="1" face="sans-serif">05/20/2015 11:11 AM</font>
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<td><font size="1" color="#5f5f5f" face="sans-serif">Subject:</font>
</td><td><font size="1" face="sans-serif">Re: [RE-wrenches] Fw: Xantrex
C-40 Drifting</font>
</td></tr><tr valign="top">
<td><font size="1" color="#5f5f5f" face="sans-serif">Sent by:</font>
</td><td><font size="1" face="sans-serif">"RE-wrenches" <<a href="mailto:re-wrenches-bounces@lists.re-wrenches.org" target="_blank">re-wrenches-bounces@lists.re-wrenches.org</a>></font></td></tr></tbody></table>
<br>
<hr noshade><div class="HOEnZb"><div class="h5">
<br>
<br>
<br><font size="3">The modules are Sunwise 22 V, 40 W modules. The
model number of the modules is </font><font size="2">SW-S40P SWT. The
are wired in series for a 24 V nominal system. That would be an mppt
voltage of 44 V on a system that directs batteries to absorb at 29.4 volts.
I'm not sure what the NOCT voltage would be, but it would seem like it
would be an ok fit? <br>
</font><font size="3"><br>
I think you are on the right track with the MPPT charging graph. The CC
likely allows pulses of full charge to hit when the batteries are at their
maximum set point voltage. <br>
<br>
Would a very short pulse of high voltage be a problem of a VRLA battery?
Could any significant gassing take place? <br>
<br>
Thanks,<br>
<br>
Drake <br>
<br>
<br>
<br>
At 06:04 PM 5/19/2015, you wrote:</font>
<br><font size="2">Hi:</font><font size="3"> <br>
</font><font size="2"><br>
We haven't changed anything the in C40. The essence of my idea was
that perhaps the "trouble" systems are the ones which have much
higher module Voc versus battery Vfloat.</font><font size="3"> <br>
</font><font size="2"><br>
JARMO</font><font size="3" color="#008000"><br>
_____________________________________________________________________________________</font><font size="3">
</font><font size="1"><b><br>
<br>
Jarmo Venalainen</b> | </font><font size="1" color="#008000"><b>Schneider
Electric </b></font><font size="1"><b> | Xantrex Brand</b> |
<b>CANADA</b> | <b>Sales Application Engineer</b> <b><br>
Phone:</b> <a href="tel:%2B604-422-2528" value="+6044222528" target="_blank">+604-422-2528</a> | <b>Tech Support:</b> <a href="tel:800-670-0707" value="+18006700707" target="_blank">800-670-0707</a>
| <b>Mobile:</b> <a href="tel:%2B604-505-0291" value="+6045050291" target="_blank">+604-505-0291</a> <b><br>
Email:</b> </font><a href="mailto:jarmo.venalainen@schneider-electric.com" target="_blank"><font size="1" color="blue"><u>jarmo.venalainen@schneider-electric.com</u></font></a><font size="1">
| <b>Site:</b></font><a href="http://www.xantrex.com/" target="_blank"><font size="3" color="blue"><u>
</u></font></a><a href="http://www.xantrex.com/" target="_blank"><font size="1" color="blue"><u>www.Xantrex.com</u></font></a><font size="1" color="blue"><u>
</u></font><font size="1"> | <b>Address:</b> 3700 Gilmore Way,
Burnaby, BC V5G4M1 </font><font size="3" color="blue"><u><br>
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From:</font><font size="3"> </font><font size="1">Ray Walters <<a href="mailto:ray@solarray.com" target="_blank">ray@solarray.com</a>></font><font size="3">
</font><font size="1" color="#5f5f5f"><br>
To:</font><font size="3"> </font><font size="1">RE-wrenches <<a href="mailto:re-wrenches@lists.re-wrenches.org" target="_blank">re-wrenches@lists.re-wrenches.org</a>>,
</font><font size="1" color="#5f5f5f"><br>
Date:</font><font size="3"> </font><font size="1">05/19/2015 11:00 AM</font><font size="3">
</font><font size="1" color="#5f5f5f"><br>
Subject:</font><font size="3"> </font><font size="1">Re: [RE-wrenches] Fw:
Xantrex C-40 Drifting</font><font size="3"> </font><font size="1" color="#5f5f5f"><br>
Sent by:</font><font size="3"> </font><font size="1">"RE-wrenches"
<<a href="mailto:re-wrenches-bounces@lists.re-wrenches.org" target="_blank">re-wrenches-bounces@lists.re-wrenches.org</a>></font><font size="3"> <br>
<br>
<br>
<br>
<br>
Hi Jarmo;<br>
<br>
Early solar systems actually tried to use the principle of matching array
Vmpp to battery voltage in lieu of charge controllers. The
biggest issue is that when it is is hot the module voltage can drop below
the battery voltage needed, and when its cold the voltage will still be
too high. Batteries were either over charged or never reached full
charge depending on the conditions.<br>
I've used the C40 successfully for decades, so I'm wondering if the circuitry
changed recently, or if different tolerance components were substituted
that may be causing the drift?<br>
<br>
Thanks, </font><tt><font size="3"><br>
R.Ray Walters<br>
CTO, Solarray, Inc<br>
Nabcep Certified PV Installer, <br>
Licensed Master Electrician<br>
Solar Design Engineer<br>
<a href="tel:303%20505-8760" value="+13035058760" target="_blank">303 505-8760</a></font></tt><font size="3"> <br>
On 5/19/2015 10:31 AM, </font><a href="mailto:Jarmo.Venalainen@schneider-electric.com" target="_blank"><font size="3" color="blue"><u>Jarmo.Venalainen@schneider-electric.com</u></font></a><font size="3" color="blue">
</font><font size="3">wrote: </font><font size="2"><br>
Hi:</font><font size="3"> </font><font size="2"><br>
<br>
I didn't know that there were systems out there where a PWM charge controller
such as the C-40 was producing an unhealthy, high battery voltage. Since
there are, I may have a possible explanation.</font><font size="3"> </font><font size="2"><br>
<br>
The C-series and other PWM type charge controllers operate by PWM whereby
they very very quickly connect/disconnect the solar module to the battery
bank. The amount of time which the module is connected to the array
is the PWM on-period. These controllers do not have the ability to
"smooth out" the output voltage. All they can do is apply
the full module voltage OR not a</font><font size="3"> <br>
<br>
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