<font size=2 face="sans-serif">Hi:</font>
<br>
<br><font size=2 face="sans-serif">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>
<br>
<br><font size=2 face="sans-serif">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 apply any module voltage
to the battery. Here are some graphs that show this,</font>
<br>
<br><img src=cid:_1_0C99BE440C99BBE4005ABF7E88257E4A><font size=2 face="sans-serif"> </font>
<br>
<br><font size=2 face="sans-serif">It 's supposed to work out when the
battery absorbs, smooths out and averages the output voltage pulses coming
out of the PWM controller.</font>
<br>
<br><font size=2 face="sans-serif">Except, I'm hearing that, that is not
necessarily true. It sounds like on some systems the batteries will
not average voltage very well over time and indeed experience increasing
and undesirably high terminal voltages over time.</font>
<br>
<br><font size=2 face="sans-serif">If this is the mechanism, I think one
way alleviate or perhaps even eliminate the rising voltage problem is by
matching the module Voc voltage to the desired battery float voltage. For
example, if a 28 VDC float voltage was desired, then the solar module Voc
should be chosen as something slightly above 28 VDC.</font>
<br>
<br><font size=2 face="sans-serif">i.e. I think the trick is to match the
module Voc voltage to the desired battery float voltage. Perhaps
a 32 Voc module for a 28 VDC float voltage. </font>
<br>
<br><font size=2 face="sans-serif">I'm not sure what the right number is,
but if I'm correct about this mechanism, then a 50 Voc module on a 12 VDC
battery, should the kind of system which experiences this overcharging/over
voltage problem.</font>
<br>
<br><font size=2 face="sans-serif">You guys have seen many systems. Maybe
you can comment on whether the systems which have had this trouble are
also ones where the module Voc is much higher than the desired battery
float voltage. Perhaps the "trouble systems" also tend
to have a specific battery chemistry or even particular battery type.</font>
<br>
<br><font size=2 face="sans-serif">JARMO</font>
<br>
<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> +604-422-2528 | <b>Tech Support:</b> 800-670-0707
| <b>Mobile:</b> +604-505-0291 <b><br>
Email:</b> </font><a href="mailto:jarmo.venalainen@schneider-electric.com"><font size=1 color=blue face="Arial"><u>jarmo.venalainen@schneider-electric.com</u></font></a><font size=1 face="Arial">
| <b>Site:</b></font><a href=http://www.xantrex.com/ target=_blank><font size=1 color=blue face="Arial"><u>
www.Xantrex.com</u></font></a><font size=1 face="Arial"> |
<b>Address:</b> 3700 Gilmore Way, Burnaby, BC V5G4M1 <br>
</font>
<table>
<tr>
<td colspan=4><a href=http://www.xantrexrebate.com/ target=_blank><img src=cid:_1_0C9AA38C0C9AA03C005ABF7E88257E4A width=1 height=1></a>
<tr>
<td><a href=http://www.xantrex.com/ target=_blank><img src=cid:_1_0C9AAB240C9AA7A8005ABF7E88257E4A></a>
<td><a href=https://www.facebook.com/Xantrex target=_blank><img src=cid:_1_0C9AB2BC0C9AAF40005ABF7E88257E4A></a>
<td><a href=https://twitter.com/Xantrex target=_blank><img src=cid:_1_0C9ABA540C9AB6D8005ABF7E88257E4A></a>
<td><a href=https://twitter.com/Xantrex target=_blank><img src=cid:_1_0C9AC1EC0C9ABE70005ABF7E88257E4A></a></table>
<br>
<br><font size=1 color=#00a000 face="Arial"><br>
*** Please consider the environment before printing this e-mail</font><font size=3><br>
</font>
<br><font size=1 color=#800080 face="sans-serif">----- Forwarded by Jarmo
Venalainen/Canada/Schneider on 05/18/2015 07:02 PM -----</font>
<br>
<table width=100%>
<tr valign=top>
<td><font size=1 color=#5f5f5f face="sans-serif">From:</font>
<td><font size=1 face="sans-serif">Drake <drake.chamberlin@redwoodalliance.org></font>
<tr valign=top>
<td><font size=1 color=#5f5f5f face="sans-serif">To:</font>
<td><font size=1 face="sans-serif">Jarmo.Venalainen@schneider-electric.com,
</font>
<tr valign=top>
<td><font size=1 color=#5f5f5f face="sans-serif">Date:</font>
<td><font size=1 face="sans-serif">05/18/2015 03:35 PM</font>
<tr valign=top>
<td><font size=1 color=#5f5f5f face="sans-serif">Subject:</font>
<td><font size=1 face="sans-serif">Re: Fw: [RE-wrenches] Xantrex C-40 Drifting</font></table>
<br>
<hr noshade>
<br>
<br>
<br><font size=3>Hi JARMO,<br>
<br>
The battery bank consists of four, 415 AH in a Full River AGM deep cycle
batteries wired in a 24 volt series. The 80 W array is strictly
a maintainer to keep the batteries charged when the
AC coupled system is detached from the direct grid tie
inverters. The only constant loads on the system are about 3 W of power
that keeps the metering awake. The batteries are low self discharge. <br>
<br>
Thanks,<br>
<br>
Drake<br>
<br>
<br>
At 07:47 PM 5/14/2015, you wrote:</font>
<br><font size=2>Hi:</font><font size=3> <br>
</font><font size=2><br>
80W is a really small PV source, so I'm wondering how it can raise the
battery voltage so much.</font><font size=3> <br>
</font><font size=2><br>
What size is the battery?</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> +604-422-2528 | <b>Tech Support:</b> 800-670-0707
| <b>Mobile:</b> +604-505-0291 <b><br>
Email:</b> </font><a href="mailto:jarmo.venalainen@schneider-electric.com"><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/><font size=3 color=blue><u>
</u></font></a><a href=http://www.xantrex.com/><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>
</u></font><a href=http://www.xantrex.com/><img src=cid:_1_0C992F940C991B88005ABF7E88257E4A alt=[]></a><font size=3>
</font><a href=https://www.facebook.com/Xantrex><font size=3 color=blue><u> </u></font><img src=cid:_1_0C9933F80C991B88005ABF7E88257E4A alt=[]></a><a href=https://twitter.com/Xantrex><img src=cid:_1_0C99382C0C991B88005ABF7E88257E4A alt=[]></a><a href=https://twitter.com/Xantrex><img src=cid:_1_0C993C600C991B88005ABF7E88257E4A alt=[]></a><font size=3><br>
</font><font size=1 color=#00a000><br>
<br>
*** Please consider the environment before printing this e-mail</font><font size=3><br>
</font><font size=1 color=#800080><br>
----- Forwarded by Jarmo Venalainen/Canada/Schneider on 05/14/2015 04:45
PM -----</font><font size=3> </font><font size=1 color=#5f5f5f><br>
From:</font><font size=3> </font><font size=1>Drake <drake.chamberlin@redwoodalliance.org></font><font size=3>
</font><font size=1 color=#5f5f5f><br>
To:</font><font size=3> </font><font size=1>re-wrenches@lists.re-wrenches.org,
</font><font size=1 color=#5f5f5f><br>
Date:</font><font size=3> </font><font size=1>05/14/2015 04:30 PM</font><font size=3>
</font><font size=1 color=#5f5f5f><br>
Subject:</font><font size=3> </font><font size=1>[RE-wrenches] 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"
<re-wrenches-bounces@lists.re-wrenches.org></font><font size=3> <br>
<br>
<br>
<br>
<br>
I have a Xantrex C-40 that won't keep its settings. It is important that
it does because it is for a maintainer array (80 W) on an AGM battery bank,
on an AC coupled backup system. Not only could high voltage damage the
batteries, but when the voltage goes over 30 Volts, the AUX relay opens
and the grid tie inverter is isolated from the grid.<br>
<br>
After numerous sessions of reprogramming, Xantrex tech support sent me
a new unit. The problem persisted as before. A new temperature sensor helped,
but the settings still drift. It seems that rebooting the charge controller
helps for a day or so, but then it drifts again.<br>
<br>
The potentiometer settings are way below the calculated setting for 29.4
V, but it still peaks in the high 30s. I check the temperature compensated
voltages on the Outback Mate, and the temp compensated voltage runs high.
<br>
<br>
In a related side issue, the AUX relay of the FX inverters is not based
on temperature compensated voltage, which makes setting AC coupling charge
set points more problematic. <br>
<br>
Has anyone experienced a C-40 CC that drifts in its settings. What would
be a good (inexpensive) charge controller to accurately control 80 W of
PV?<br>
<br>
Thanks,<br>
<br>
Drake <br>
<br>
Drake Chamberlin<i><br>
Athens Electric LLC<br>
OH License 44810<br>
CO License 3773<br>
NABCEP Certified Solar PV <br>
740-448-7328</i></font><font size=3 color=blue><u><br>
</u></font><a href="http://athens-electric.com/"><font size=3 color=blue><u>http://athens-electric.com/</u></font></a><font size=3 color=blue>
</font><font size=3><br>
<br>
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