[RE-wrenches] Design Question re Battery Bank Sizing

[Ray Walters]

Hi Allan;

B&B battery, which I've used for years for sealed battery applications 
has excellent charts on discharge rate vs time; just what you need for 
your design.  I've also found them to have stable voltage under very 
heavy loads (electric vehicles) right up until they're fully 
discharged.  I don't really know about the Concordes.

Ray

On 2/15/2012 10:53 AM, Allan Sindelar 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_ <mailto: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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