<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Alan,<div><br></div><div>See if you can find the locked rotor amps (LRA) for this pump. Design to provide that much current for starting the pump. My guess is about 7-9kW for a 3HP.</div><div><br></div><div>I'm not a fan of multiple parallel strings but you are correct that parallel strings will produce more instantaneous current. However in this case, I don't recommend it. Even with other loads it is not likely you will demand more than 250 amps @ 48Vdc draw on the battery to start the pump. That is not excessive for an AGM battery, especially since it is very short duration. </div><div><br></div><div>If you need more battery capacity, opt for lower voltage batteries instead of paralleling.<br><div>
<span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><br class="Apple-interchange-newline">Larry Crutcher</div><div>Starlight Solar Power Systems</div></div></span></span><div>(928) 342-9103</div><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><u><br></u></div><div><u><br></u></div></div></span></span></span><br class="Apple-interchange-newline">
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<br><div><div>On Feb 15, 2012, at 10:53 AM, Allan Sindelar wrote:</div><br class="Apple-interchange-newline">
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Esteemed fellow Wrenches,<br>
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.<br>
<br clear="all">
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.<br>
<br>
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.<br>
<br>
What's your best guess at the smallest size battery bank that would
reliably start this pump, and how would it best be configured? <br>
<br>
Thank you,<br>
Allan<br>
<br>
<br>
<div class="moz-signature"> <font face="Times New Roman, Times,
serif"><b>Allan Sindelar</b></font><br>
<small><a href="mailto:Allan@positiveenergysolar.com"><font color="#000099" face="Times New Roman, Times, serif"><u>Allan@positiveenergysolar.com</u></font></a></small><font face="Times New Roman, Times, serif"><br>
<span style="font-size: 10pt;">NABCEP Certified Photovoltaic
Installer<br>
NABCEP Certified Technical Sales Professional<br>
New Mexico EE98J Journeyman Electrician<br>
<b>Positive Energy, Inc.</b><br>
3201 Calle Marie<br>
Santa Fe, New Mexico 87507<br>
<b>505 424-1112</b><br>
<a href="http://www.positiveenergysolar.com/" target="_blank"><u>www.positiveenergysolar.com</u></a></span></font>
</div>
<br>
<br>
<br>
</div>
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