[RE-wrenches] Small Wh and large LRA

[Darryl Thayer]

I agree with Warren, the batterys have a big job to do here,   If you have a 48 volt system the batteries will have to supply about 180 amps, this is a large surge and your need to be large or fast the AGM are good for surge, flooded would have to be larger (AH) to handle the same surge.  
 
The inverter system could be one of several I have done a similar system on a 120 amp surge,  I used Outback, and when the big motor was called, I used two relays, when the call for pump the first relay closed and energized the extra Outbacks, then the second relay wihch was a time delay closed to energize the load.  When the load had stabilized the extra outbacks would turn off.  For your situation I would recomend two Outbacks,  The master slave, on energy save, turn on usually is not fast enough and the surge will kick out the first inverter.      
 

 

--- On Thu, 3/18/10, Warren Lauzon <windsun at wind-sun.com> wrote:


From: Warren Lauzon <windsun at wind-sun.com>
Subject: Re: [RE-wrenches] Small Wh and large LRA
To: "RE-wrenches" <re-wrenches at lists.re-wrenches.org>
Date: Thursday, March 18, 2010, 5:41 AM



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The kicker is the large startup, so you may need to use batteries with low internal resistance, such as the Concorde AGM's. You will also have to make sure your cables are good for the max current to avoid any voltage drop which would cause a low voltage shutdown.
 
Aside from that, just go with around 200-250 AH of battery storage (assuming 12 volts). A pair of golf car size batteries would probably work if they are something like Crown or Trojan.
 
..................................................................................................
Northern Arizona Wind & Sun - Electricity From The Sun Since 1979
Solar Discussion Forum: http://www.wind-sun.com/ForumVB/
..................................................................................................

----- Original Message ----- 
From: Mark Dickson 
To: 'RE-wrenches' 
Sent: Wednesday, March 17, 2010 2:56 PM
Subject: [RE-wrenches] Small Wh and large LRA



Hello Wrenches, 
I’ve been asked to design a battery based PV system for a load that has a high start up surge of about 62A @ 115V.  The thing is, once it is running it will only run for ~10 minutes per day at 11A.  So the daily loads are very low.  How do I size a battery bank large enough to handle the large start-up surge, yet reasonable enough to cover the modest daily load?  Is there a rule-of-thumb for this?
 

Best regards,
 
Mark Dickson,
NABCEP Certified Solar PV Installer ™
Oasis Montana Inc.



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