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William,<br>
<br>
I'll try to add a little to Allan's and <font size="3">Ronald Parades'
comments. Nearly every battery manufacturer specifies a maximum 80%
depth of discharge (DOD); that corresponds to about 10.5 volts for a
nominal 12-volt battery. Notice how close that is to the default
setting used by many inverter manufacturers for starting the generator
right away. For deep-cycle batteries, a cycle life in the low hundreds
should be expected for a battery that is routinely discharged to 80%
DOD. <br>
<br>
Designing for a lower DOD will result in longer battery life. I've got
a table from Ronald that shows the L16RE battery life expectancy is
about 7 years for a 25% daily DOD. Since that is their warranty target,
it seems like they should specify a 25% daily average DOD in the
battery instructions. <br>
<br>
If charging primarily with a generator, 50% DOD before starting the
generator is good compromise (but the generator shouldn't have to start
every day, every other day maybe). Fuel economy really falls off the
chart while charging above 90% SOC. So if you are starting a generator
at 75% and charging to 100% it'll use a lot more fuel that using the
generator to charge from 50% to 80% or 85%. Trouble is that routinely
charging to only 85% SOC will lead to sulfation problems. That can
shorten the battery life too.<br>
<br>
Kent Osterberg<br>
Blue Mountain Solar, Inc.<br>
<br>
</font><br>
<br>
Allan Sindelar wrote:
<blockquote cite="mid:4D8D08ED.9060709@positiveenergysolar.com"
type="cite">
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William,<br>
I use 80%, as the intent is that this is maximum, not typical. It's
directly used to calculate the battery capacity on the spreadsheet. 50%
is more of a target occasional DoD, but it's not a maximum.<br>
<br>
In the sunny Southwest where Windy and I are planted, that's pretty
safe, as multiple days without sun happen, but not frequently. It may
be less so in Atascadero.<br>
Allan<br>
<br>
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<title></title>
<font face="Times New Roman, Times, serif"><b>Allan Sindelar</b></font><br>
<small><a moz-do-not-send="true"
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 moz-do-not-send="true" href="http://www.positiveenergysolar.com/"
target="_blank"><u>www.positiveenergysolar.com</u></a><o:p></o:p></span></font>
<p class="MsoNormal" style="margin-right: 722.25pt;"><span
style="font-size: 10pt;"><font
face="Times New Roman, Times,
serif"><st1:place w:st="on"><st1:city
w:st="on"></st1:city><st1:state w:st="on"></st1:state><st1:postalcode
w:st="on"></st1:postalcode></st1:place></font><b style=""><br>
</b></span></p>
<span style="font-size: 10pt;"><br>
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<br>
On 3/25/2011 1:48 PM, William Miller wrote:
<blockquote
cite="mid:6.0.1.1.2.20110325124537.02e15fd8@millersolar.com"
type="cite"> <font size="3">Friends:<br>
<br>
I am using a modified version of the Dankoff load chart (with credit
given) to calculate off-grid loads. There is a section where you enter
the maximum depth of discharge (DOD) for a battery bank. It is my
understanding that the maximum DOD for a lead acid battery bank is 50%.<br>
<br>
Is this correct in concept?<br>
<br>
Is this a correct value to enter in this cell?<br>
<br>
Thanks,<br>
<br>
William Miller<br>
<br>
PS: I called Ronald Parades at Trojan before this e-mail was sent and
here is what he said: He recommends 20%-30% DOD. Any greater DOD
results in shorter battery life. He noted that in many approaches a
design criteria of multi-day autonomy which is rarely or never used
actually calculates into the final AH result as a virtual decrease in
DOD.<br>
<br>
Wm<br>
<br>
<x-sigsep></x-sigsep></font>
<p> <font size="3">Miller Solar<br>
Voice :805-438-5600<br>
email: <a moz-do-not-send="true" class="moz-txt-link-abbreviated"
href="mailto:william@millersolar.com">william@millersolar.com</a><br>
<a moz-do-not-send="true" href="http://millersolar.com/"
eudora="autourl">http://millersolar.com<br>
</a>License No. C-10-773985<br>
</font></p>
</blockquote>
<br>
</blockquote>
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