[RE-wrenches] Fw: Xantrex C-40 Drifting
boB at midnitesolar.com
boB at midnitesolar.com
Thu May 21 12:07:43 PDT 2015
The old 48V SW inverter, designed by the same person (Greg) that designed
the C-40, C-12, C-6 and C-60 only has a 0.4 volt resolution. Does the
C-series
CC's also have this resolution ? Maybe that's why you might see a +-0.2
or 0.3 volt
variation ? Not that big of a deal usually for a 48V battery.
That circuit, like most PWM chargers, regulate the "average" DC battery
voltage so some
peak and valley voltages are going to happen.
boB
On 5/21/2015 9:47 AM, Jarmo.Venalainen at schneider-electric.com wrote:
> Hi:
>
> 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.
>
> What does change a lot is the intensity of the sun and thereby the
> Voc, Vmp, Imp, etc. of the module/array.
>
> 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.
>
> It's an idea. It may be right or wrong. Some trials would be needed
> to prove or disprove it.
>
> 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.venalainen at schneider-electric.com_
> <mailto:jarmo.venalainen at 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: Steve Bell <sbell at morningstarcorp.com>
> To: RE-wrenches <re-wrenches at lists.re-wrenches.org>,
> Date: 05/21/2015 09:25 AM
> Subject: Re: [RE-wrenches] Fw: Xantrex C-40 Drifting
> Sent by: "RE-wrenches" <re-wrenches-bounces at lists.re-wrenches.org>
>
>
> ------------------------------------------------------------------------
>
>
>
> 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.Venalainen at schneider-electric.com_
> <mailto:Jarmo.Venalainen at 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_ <tel:%2B604-422-2528> | *Tech Support:*
> _800-670-0707_ <tel:800-670-0707> | *Mobile:* _+604-505-0291_
> <tel:%2B604-505-0291>*
> Email:* _jarmo.venalainen at schneider-electric.com_
> <mailto:jarmo.venalainen at 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.chamberlin at redwoodalliance.org_
> <mailto:drake.chamberlin at redwoodalliance.org>>
> To: RE-wrenches <_re-wrenches at lists.re-wrenches.org_
> <mailto:re-wrenches at 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-bounces at lists.re-wrenches.org_
> <mailto:re-wrenches-bounces at 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_ <tel:%2B604-422-2528> | *Tech Support:*
> _800-670-0707_ <tel:800-670-0707> | *Mobile:* _+604-505-0291_
> <tel:%2B604-505-0291>*
> Email:* _jarmo.venalainen at schneider-electric.com_
> <mailto:jarmo.venalainen at schneider-electric.com> | *Site:*__
> <http://www.xantrex.com/>_www.Xantrex.com_
> <http://www.xantrex.com/>__ | *Address:* 3700 Gilmore Way, Burnaby,
> BC V5G4M1 _
> _[] <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:Ray Walters <_ray at solarray.com_ <mailto:ray at solarray.com>>
> To:RE-wrenches <_re-wrenches at lists.re-wrenches.org_
> <mailto:re-wrenches at 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-bounces at lists.re-wrenches.org_
> <mailto:re-wrenches-bounces at 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_ <tel:303%20505-8760>
> On 5/19/2015 10:31 AM, _Jarmo.Venalainen at schneider-electric.com_
> <mailto:Jarmo.Venalainen at 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
>
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