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<font size="3" face="Lucida Grande">Hi Hugh & Wrenches,</font> </p>
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<font size="3" face="Lucida Grande">Regarding the charge voltages you sited, you've got the gist.</font> </p>
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<font size="3" face="Lucida Grande">As battery temperature drops, you need to increase the charge voltage to properly charge and, conversely, as temperatures rise, voltage needs to be decreased to reduce the risk of overcharging.</font> </p>
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<font size="3" face="Lucida Grande">I believe the range we site to accommodate for temperature is (in C);</font> </p>
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<font size="3" face="Lucida Grande">0-16C: 2.5VPC</font> </p>
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<font size="3" face="Lucida Grande">17-27C: 2.4VPC</font> </p>
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<font size="3" face="Lucida Grande">28-40C: 2.36VPC</font> </p>
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<font size="3" face="Lucida Grande">These are your max bulk / absorb voltage settings.</font> </p>
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<font size="3" face="Lucida Grande">Regarding a low voltage disconnect, there is a significant difference between on load and at rest voltages at 50% SOC.</font> </p>
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<font size="3" face="Lucida Grande">Below is a table of a cell being discharged at a known constant load (C/20) over time at 25C;</font> </p>
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<font size="3" face="Lucida Grande">SOC VPC</font> </p>
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<font size="3" face="Lucida Grande">100% 2.1</font> </p>
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<font size="3" face="Lucida Grande">75% 2.01</font> </p>
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<font size="3" face="Lucida Grande">50% 1.93</font> </p>
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<font size="3" face="Lucida Grande">25% 1.84</font> </p>
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<font size="3" face="Lucida Grande">0% 1.75</font> </p>
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<font size="3" face="Lucida Grande">Please note, this is for a cell(s) under constant load and at 25C. If the load increased, you would see lower voltages more quickly, Moreover, once the load is removed, resting voltages will increase dramatically, i.e. 1.75VPC on load will equal ~1.95VPC at rest. If you were using 2.0VPC (on load) as your cut off, you would only have been able to discharge ~25% - which does not include capacity reduction due to temps <25C.......and I know they are lower than that here!</font> </p>
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<font size="3" face="Lucida Grande">Hope this is of some assistance.</font> </p>
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<font size="3" face="Lucida Grande">Regards,</font> </p>
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<font size="3" face="Lucida Grande">Jamie</font> </p>
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<font size="3" face="Lucida Grande"><font face="Lucida Grande" STYLE="font-size: 12pt"><br>James Surrette<BR><BR>Surrette Battery Co. Ltd<BR>1 Station Rd.<BR>Springhill, NS, CAN<BR>B0M 1X0<BR><BR>Direct: 902.597.4027<BR>Fax: 902.597.8447<BR><BR><BR><br><br></font>>>> Hugh <hugh@scoraigwind.co.uk> 1/13/2010 2:26 PM >>></font> </p>
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<font size="3" face="Lucida Grande">Hi wrenches,</font> </p>
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<font size="3" face="Lucida Grande">I have been selling and using a few sets of Rolls 4000 series S530</font> </p>
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<font size="3" face="Lucida Grande">batteries lately.</font> </p>
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<font size="3" face="Lucida Grande">I have downloaded the Solar Battery manual from </font><i><u><a href="http://www.rollsbattery.com"><font face="Lucida Grande" size="3" color="#0000ff">www.rollsbattery.com</font></a></u></i><font size="3" face="Lucida Grande"></font> </p>
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<font size="3" face="Lucida Grande">It's very interesting. At 17 degrees C you need to charge at 14.4</font> </p>
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<font size="3" face="Lucida Grande">volts. At 16 degrees it's 15 volts. Hmm, Ok I get the idea. I am</font> </p>
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<font size="3" face="Lucida Grande">certainly learning to compensate my temperatures this winter.</font> </p>
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<font size="3" face="Lucida Grande">I did a search in the document for the word 'discharge'. I am</font> </p>
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<font size="3" face="Lucida Grande">cutting off at just below nominal voltage and starting my generator.</font> </p>
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<font size="3" face="Lucida Grande">I do not get much capacity. A customer has suggested that a lot of</font> </p>
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<font size="3" face="Lucida Grande">the discharge capacity is to be had at 11.5 volts (he has a 12v</font> </p>
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<font size="3" face="Lucida Grande">system obviously). Hmm. Sounds a bit harsh. But what voltage</font> </p>
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<font size="3" face="Lucida Grande">should I be considering to be 50% discharged, and time to start the</font> </p>
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<font size="3" face="Lucida Grande">genny? And in a hard frost, the same voltage?</font> </p>
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<font size="3" face="Lucida Grande">No mention of discharge in the solar battery manual. Any ideas anyone?</font> </p>
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<font size="3" face="Lucida Grande">Please don't tell me to buy an amphour meter (or worse still to sell</font> </p>
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<font size="3" face="Lucida Grande">them). Those things are way too confusing to calibrate. I can tell</font> </p>
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<font size="3" face="Lucida Grande">you that I am not getting many amphours out of my batteries in these</font> </p>
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<font size="3" face="Lucida Grande">low temperatures before the voltage per cell drops below 2.</font> </p>
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<font size="3" face="Lucida Grande">What do I tell my customers about the end-of-discharge voltage for</font> </p>
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<font size="3" face="Lucida Grande">sustainable cycling of their Rolls batteries? And is it temp</font> </p>
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<font size="3" face="Lucida Grande">compensated?</font> </p>
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<font size="3" face="Lucida Grande">thanks</font> </p>
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<font size="3" face="Lucida Grande">--</font> </p>
<p style="margin-top: 0; margin-bottom: 0">
<font size="3" face="Lucida Grande">Hugh Piggott</font> </p>
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<font size="3" face="Lucida Grande">Scoraig Wind Electric</font> </p>
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<font size="3" face="Lucida Grande">Scotland</font> </p>
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<u><i><a href="http://www.scoraigwind.co.uk"><font face="Lucida Grande" size="3" color="#0000ff">http://www.scoraigwind.co.uk</font></a></i></u><font size="3" face="Lucida Grande"></font> </p>
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