[RE-wrenches] Design Question re Battery Bank Sizing

[Comet Systems]

You need to know the Locked Rotor Amps (LRA) and the pump class for the
pump, there are calculators on the web that can help you size an inverter
for that application.

On Wed, Feb 15, 2012 at 1:53 PM, Allan Sindelar <
allan at positiveenergysolar.com> wrote:

> **
> Esteemed fellow Wrenches,
> We need to size a battery bank for a GTWB just for starting a well pump.
> The well is on its own meter, so as long as the battery voltage does not
> crash when the pump starts there will be plenty of capacity left over for
> minimal loads.  We'll be using sealed batteries, most likely Concorde
> SunXtenders. According to theSunXtender Technical Manual, Concordes can
> handle up to a C/0.2 charge rate (500A for a 100Ah battery), but there is
> no discussion of maximum discharge rates or voltage drop due to large surge
> loads.
>
> The pump is 3HP and is conventional 3-wire, not soft-start. The well is
> 940ft. and the depth to water is unknown. It pumps into a pressure tank,
> not open discharge. Customers are not interested in replacing the pump, but
> might be talked into adding a soft start Franklin controller, although at
> this preliminary design stage we're not certain one is available for this
> particular model. The inverter would be a Radian, so system voltage is 48V.
>
> I would think that configuration would make a difference, as well as size.
> Using 12V batteries in series/parallel would minimize interconnect and
> terminal resistance. I think that it would also allow multiple paths for
> discharge current, reducing the voltage dip.
>
> What's your best guess at the smallest size battery bank that would
> reliably start this pump, and how would it best be configured?
>
> Thank you,
> Allan
>
>
>  *Allan Sindelar*
> *Allan at positiveenergysolar.com* <Allan at positiveenergysolar.com>
> NABCEP Certified Photovoltaic Installer
> NABCEP Certified Technical Sales Professional
> New Mexico EE98J Journeyman Electrician
> *Positive Energy, Inc.*
> 3201 Calle Marie
> Santa Fe, New Mexico 87507
> *505 424-1112*
> *www.positiveenergysolar.com* <http://www.positiveenergysolar.com/>
>
>
>
>
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-- 
Chris Mason
President, Comet Systems Ltd
masonc at cometsystems.co
www.cometsystems.co
Cell: 264.235.5670
Int: +1305.767.2094
Skype: netconcepts
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