Hello Wrenches, 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. I don't know if this is a component of the problem, but thought I would mention it.
Best Regards, Steve Bell On Wed, May 20, 2015 at 7:34 PM, <jarmo.venalai...@schneider-electric.com> wrote: > Hi: > > 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. > > 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. > > 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. > > JARMO > > > > _____________________________________________________________________________________ > > * Jarmo Venalainen* | * Schneider Electric ** | Xantrex Brand* | > *CANADA* | *Sales Application Engineer* > * Phone:* +604-422-2528 | *Tech Support:* 800-670-0707 | *Mobile:* > +604-505-0291 > * Email:* *jarmo.venalai...@schneider-electric.com* > <jarmo.venalai...@schneider-electric.com> | *Site:** www.Xantrex.com* > <http://www.xantrex.com/> | *Address:* 3700 Gilmore Way, Burnaby, BC > V5G4M1 > <http://www.xantrexrebate.com/> <http://www.xantrex.com/> > <https://www.facebook.com/Xantrex> <https://twitter.com/Xantrex> > <https://twitter.com/Xantrex> > > > *** Please consider the environment before printing this e-mail > > > > From: Drake <drake.chamber...@redwoodalliance.org> To: RE-wrenches < > re-wrenches@lists.re-wrenches.org>, Date: 05/20/2015 11:11 AM Subject: Re: > [RE-wrenches] Fw: Xantrex C-40 Drifting Sent by: "RE-wrenches" < > re-wrenches-boun...@lists.re-wrenches.org> > ------------------------------ > > > > The modules are Sunwise 22 V, 40 W modules. The model number of the > modules is 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? > > 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. > > Would a very short pulse of high voltage be a problem of a VRLA battery? > Could any significant gassing take place? > > Thanks, > > Drake > > > > At 06:04 PM 5/19/2015, you wrote: > Hi: > > 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. > > JARMO > > _____________________________________________________________________________________ > > * Jarmo Venalainen* | *Schneider Electric ** | Xantrex Brand* | > *CANADA* | *Sales Application Engineer* > * Phone:* +604-422-2528 | *Tech Support:* 800-670-0707 | *Mobile:* > +604-505-0291 > * Email:* *jarmo.venalai...@schneider-electric.com* > <jarmo.venalai...@schneider-electric.com> | *Site:* > <http://www.xantrex.com/>*www.Xantrex.com* <http://www.xantrex.com/> | > *Address:* 3700 Gilmore Way, Burnaby, BC V5G4M1 > [image: []] <http://www.xantrex.com/> [image: []] > <https://www.facebook.com/Xantrex>[image: []] > <https://twitter.com/Xantrex>[image: []] <https://twitter.com/Xantrex> > > > *** Please consider the environment before printing this e-mail > > > > From: Ray Walters <r...@solarray.com> > To: RE-wrenches <re-wrenches@lists.re-wrenches.org>, > Date: 05/19/2015 11:00 AM > Subject: Re: [RE-wrenches] Fw: Xantrex C-40 Drifting > Sent by: "RE-wrenches" <re-wrenches-boun...@lists.re-wrenches.org> > > > > > Hi Jarmo; > > 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. > 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? > > Thanks, > R.Ray Walters > CTO, Solarray, Inc > Nabcep Certified PV Installer, > Licensed Master Electrician > Solar Design Engineer > 303 505-8760 > On 5/19/2015 10:31 AM, *jarmo.venalai...@schneider-electric.com* > <jarmo.venalai...@schneider-electric.com> wrote: > Hi: > > 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. > > 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 > > > ______________________________________________________________________ > This email has been scanned by the Symantec Email Security.cloud service. > ______________________________________________________________________ > _______________________________________________ > List sponsored by Redwood Alliance > > List Address: RE-wrenches@lists.re-wrenches.org > > Change listserver email address & settings: > *http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org* > <http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org> > > List-Archive: > *http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html* > <http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html> > > List rules & etiquette: > *www.re-wrenches.org/etiquette.htm* > <http://www.re-wrenches.org/etiquette.htm> > > Check out or update participant bios: > *www.members.re-wrenches.org* <http://www.members.re-wrenches.htm> > > > > > > _______________________________________________ > List sponsored by Redwood Alliance > > List Address: RE-wrenches@lists.re-wrenches.org > > Change listserver email address & settings: > *http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org* > <http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org> > > List-Archive: > *http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html* > <http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html> > > List rules & etiquette: > *www.re-wrenches.org/etiquette.htm* > <http://www.re-wrenches.org/etiquette.htm> > > Check out or update participant bios: > *www.members.re-wrenches.org* <http://www.members.re-wrenches.org/> > > ______________________________________________________________________ > This email has been scanned by the Symantec Email Security.cloud service. > ______________________________________________________________________ > _______________________________________________ > List sponsored by Redwood Alliance > > List Address: RE-wrenches@lists.re-wrenches.org > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > www.members.re-wrenches.org > > > > > _______________________________________________ > List sponsored by Redwood Alliance > > List Address: RE-wrenches@lists.re-wrenches.org > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > www.members.re-wrenches.org > > >
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