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<br>
The old 48V SW inverter, designed by the same person (Greg) that
designed<br>
the C-40, C-12, C-6 and C-60 only has a 0.4 volt resolution. Does
the C-series<br>
CC's also have this resolution ? Maybe that's why you might see a
+-0.2 or 0.3 volt<br>
variation ? Not that big of a deal usually for a 48V battery.<br>
<br>
That circuit, like most PWM chargers, regulate the "average" DC
battery voltage so some<br>
peak and valley voltages are going to happen. <br>
<br>
boB<br>
<br>
<br>
<br>
On 5/21/2015 9:47 AM, <a class="moz-txt-link-abbreviated" href="mailto:Jarmo.Venalainen@schneider-electric.com">Jarmo.Venalainen@schneider-electric.com</a>
wrote:<br>
</div>
<blockquote
cite="mid:OF12661C89.767472DC-ON88257E4C.005B546F-88257E4C.005C4638@US.Schneider-Electric.com"
type="cite"><font face="sans-serif" size="2">Hi:</font>
<br>
<br>
<font face="sans-serif" size="2">The C40 circuit is a really
simple circuit
made up of a set of resistors, capacitors, op-amps, a time-base
crystal
and PWM. Simple electronic components, so I don't see drift
issues,
except maybe under large temperature changes.</font>
<br>
<br>
<font face="sans-serif" size="2">What does change a lot is the
intensity
of the sun and thereby the Voc, Vmp, Imp, etc. of the
module/array.</font>
<br>
<br>
<font face="sans-serif" size="2">Given that the PWM applies the
varying
"raw" available array voltage/current directly to the battery,
I think that's how the output voltage variation issue arises.</font>
<br>
<br>
<font face="sans-serif" size="2">It's an idea. It may be right
or wrong. Some trials would be needed to prove or disprove it.</font>
<br>
<br>
<font face="sans-serif" size="2">JARMO <br>
</font><font color="#008000" size="3">_____________________________________________________________________________________</font><font
size="3">
<br>
</font><font face="Arial" size="1"><b><br>
Jarmo Venalainen</b> | </font><font color="#008000"
face="Arial" size="1"><b>
Schneider Electric </b></font><font face="Arial" 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>
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<td><font color="#5f5f5f" face="sans-serif" size="1">From:</font>
</td>
<td><font face="sans-serif" size="1">Steve Bell
<a class="moz-txt-link-rfc2396E" href="mailto:sbell@morningstarcorp.com"><sbell@morningstarcorp.com></a></font>
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<td><font color="#5f5f5f" face="sans-serif" size="1">To:</font>
</td>
<td><font face="sans-serif" size="1">RE-wrenches
<a class="moz-txt-link-rfc2396E" href="mailto:re-wrenches@lists.re-wrenches.org"><re-wrenches@lists.re-wrenches.org></a>,
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<td><font color="#5f5f5f" face="sans-serif" size="1">Date:</font>
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<td><font face="sans-serif" size="1">05/21/2015 09:25 AM</font>
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<td><font color="#5f5f5f" face="sans-serif" size="1">Subject:</font>
</td>
<td><font face="sans-serif" size="1">Re: [RE-wrenches] Fw:
Xantrex C-40 Drifting</font>
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<td><font color="#5f5f5f" face="sans-serif" size="1">Sent
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<td><font face="sans-serif" size="1">"RE-wrenches"
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<br>
<br>
<br>
<font size="3">Hello Wrenches,</font>
<br>
<br>
<font size="3">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.</font>
<br>
<font size="3">I don't know if this is a component of the problem,
but
thought I would mention it.</font>
<br>
<br>
<font size="3">Best Regards,</font>
<br>
<br>
<font size="3">Steve Bell</font>
<br>
<font size="3"> </font>
<br>
<br>
<br>
<br>
<font size="3">On Wed, May 20, 2015 at 7:34 PM, <</font><a
moz-do-not-send="true"
href="mailto:Jarmo.Venalainen@schneider-electric.com"
target="_blank"><font color="blue" size="3"><u>Jarmo.Venalainen@schneider-electric.com</u></font></a><font
size="3">>
wrote:</font>
<br>
<font face="sans-serif" size="2">Hi:</font><font size="3"> <br>
</font><font face="sans-serif" size="2"><br>
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><font
size="3"> <br>
</font><font face="sans-serif" size="2"><br>
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><font
size="3"> <br>
</font><font face="sans-serif" size="2"><br>
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><font size="3"> <br>
</font><font face="sans-serif" size="2"><br>
JARMO</font><font size="3"> <br>
</font><font face="sans-serif" size="2"><br>
</font><font color="#008000" size="3"><br>
_____________________________________________________________________________________</font><font
size="3">
</font><font face="Arial" size="1"><b><br>
<br>
Jarmo Venalainen</b> | </font><font color="#008000"
face="Arial" size="1"><b>
Schneider Electric </b></font><font face="Arial" size="1"><b>
| Xantrex
Brand</b> | <b>CANADA</b> | <b>Sales Application
Engineer</b> <b><br>
Phone:</b> </font><a moz-do-not-send="true"
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<td width="13%"><font color="#5f5f5f" face="sans-serif"
size="1">From:</font><font size="3">
</font>
</td>
<td width="86%"><font face="sans-serif" size="1">Drake <</font><a
moz-do-not-send="true"
href="mailto:drake.chamberlin@redwoodalliance.org"
target="_blank"><font color="blue" face="sans-serif"
size="1"><u>drake.chamberlin@redwoodalliance.org</u></font></a><font
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<td><font face="sans-serif" size="1">RE-wrenches <</font><a
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href="mailto:re-wrenches@lists.re-wrenches.org"
target="_blank"><font color="blue" face="sans-serif"
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<td><font color="#5f5f5f" face="sans-serif" size="1">Date:</font><font
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<td><font face="sans-serif" size="1">05/20/2015 11:11 AM</font><font
size="3">
</font>
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<td><font color="#5f5f5f" face="sans-serif" size="1">Subject:</font><font
size="3">
</font>
</td>
<td><font face="sans-serif" size="1">Re: [RE-wrenches] Fw:
Xantrex
C-40 Drifting</font><font size="3"> </font>
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<td><font color="#5f5f5f" face="sans-serif" size="1">Sent
by:</font><font size="3">
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<td><font face="sans-serif" size="1">"RE-wrenches" <</font><a
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target="_blank"><font color="blue" face="sans-serif"
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<font size="3"><br>
</font>
<hr noshade="noshade">
<br>
<font size="3"><br>
<br>
<br>
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? </font><font size="3"><br>
<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><font size="2"><br>
Hi:</font><font size="3"> </font><font size="2"><br>
<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"> </font><font
size="2"><br>
<br>
JARMO</font><font color="#008000" size="3"><br>
_____________________________________________________________________________________</font><font
size="3">
</font><font size="1"><b><br>
<br>
Jarmo Venalainen</b> | </font><font color="#008000" size="1"><b>Schneider
Electric
</b></font><font size="1"><b> | Xantrex Brand</b> |
<b>CANADA</b> | <b>Sales Application Engineer</b> <b><br>
Phone:</b> </font><a moz-do-not-send="true"
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From:</font><font size="3"> </font><font size="1">Ray Walters
<</font><a moz-do-not-send="true"
href="mailto:ray@solarray.com" target="_blank"><font
color="blue" size="1"><u>ray@solarray.com</u></font></a><font
size="1">></font><font size="3">
</font><font color="#5f5f5f" size="1"><br>
To:</font><font size="3"> </font><font size="1">RE-wrenches
<</font><a moz-do-not-send="true"
href="mailto:re-wrenches@lists.re-wrenches.org" target="_blank"><font
color="blue" size="1"><u>re-wrenches@lists.re-wrenches.org</u></font></a><font
size="1">>,
</font><font color="#5f5f5f" size="1"><br>
Date:</font><font size="3"> </font><font size="1">05/19/2015
11:00 AM</font><font size="3">
</font><font color="#5f5f5f" size="1"><br>
Subject:</font><font size="3"> </font><font size="1">Re:
[RE-wrenches] Fw:
Xantrex C-40 Drifting</font><font size="3"> </font><font
color="#5f5f5f" size="1"><br>
Sent by:</font><font size="3"> </font><font size="1">"RE-wrenches"
<</font><a moz-do-not-send="true"
href="mailto:re-wrenches-bounces@lists.re-wrenches.org"
target="_blank"><font color="blue" size="1"><u>re-wrenches-bounces@lists.re-wrenches.org</u></font></a><font
size="1">></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</font></tt><tt><font color="blue"
size="3"><u><br>
</u></font></tt><a moz-do-not-send="true"
href="tel:303%20505-8760" target="_blank"><tt><font color="blue"
size="3"><u>303
505-8760</u></font></tt></a><font size="3"> <br>
On 5/19/2015 10:31 AM, </font><a moz-do-not-send="true"
href="mailto:Jarmo.Venalainen@schneider-electric.com"
target="_blank"><font color="blue" size="3"><u>Jarmo.Venalainen@schneider-electric.com</u></font></a><font
color="blue" size="3">
</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>
</font><br>
</blockquote>
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