<html><head><meta http-equiv="Content-Type" content="text/html charset=windows-1252"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;">Truth is there is likely more than enough capacity in the LFP battery the customer has but the manufacturer built a limit into the “box". The limit of our battery is set to 10C for 30 seconds. WAY more than any inverter can draw with even a small bank.<div><br></div><div>Larry<br>
<br><div><div>On Sep 18, 2014, at 12:26 PM, <a href="mailto:boB@midnitesolar.com">boB@midnitesolar.com</a> wrote:</div><br class="Apple-interchange-newline"><div>
<meta content="text/html; charset=ISO-8859-1" http-equiv="Content-Type">
<div bgcolor="#FFFFFF" text="#000000">
<div class="moz-cite-prefix"><br>
Yes, well of course there are these details.<br>
If the LFP surge is a limitation, but not its amount of overall<br>
energy storage, then you may have to add a very large amount of
LFP storage to overcome that which<br>
could be overkill and cost a lot of extra $.<br>
<br>
It's all a compromise.<br>
<br>
boB<br>
<br>
<br>
On 9/18/2014 10:55 AM, Starlight Solar Power Systems wrote:<br>
</div>
<blockquote cite="mid:13511563-8B62-4F9B-B9CB-3C305296AF37@starlightsolar.com" type="cite">
<meta http-equiv="Content-Type" content="text/html;
charset=ISO-8859-1">
boB,
<div><br>
</div>
<div>When charging a LFP battery, the charge terminates when
absorb voltage is reached unless you have an enormous charger in
which case you will need to terminate based on AH returned. You
would also need to isolate the LA battery to finish charging it.
Plus, LA needs higher voltages than LFP. I don’t think would
solve Williams problem. A better solution would be another
LI-ion bank that is not current limited. Just a 50AH bank could
provide an additional 500amps.</div>
<div><br>
</div>
<div>Larry</div>
<div>
<br>
<div>
<div>On Sep 18, 2014, at 11:09 AM, <a moz-do-not-send="true" href="mailto:boB@midnitesolar.com">boB@midnitesolar.com</a>
wrote:</div>
<br class="Apple-interchange-newline">
<div>
<meta content="text/html; charset=ISO-8859-1" http-equiv="Content-Type">
<div bgcolor="#FFFFFF" text="#000000">
<div class="moz-cite-prefix"><br>
One thing that could possibly be done is to have a
smaller lead acid battery in parallel with the LiFePo
bank<br>
so the LiFePo contains most of the "energy" storage, but
the LA can supply the surges and low impedance<br>
source voltage.<br>
<br>
boB<br>
<br>
<br>
<br>
On 9/18/2014 8:53 AM, Starlight Solar Power Systems
wrote:<br>
</div>
<blockquote cite="mid:2FFB003A-CA9B-4996-B690-53023C53366B@starlightsolar.com" type="cite">
<meta http-equiv="Content-Type" content="text/html;
charset=ISO-8859-1">
William,
<div><br>
</div>
<div>This is one reason I choose to avoid the "black
box" approach to Li-ion batteries for our customers.
There are several companies offering enclosed
battery/controls like the OES. Their approach does not
match well to the off-grid and mobile markets that I
serve. </div>
<div><br>
</div>
<div>Since most LFP batteries can handle 10C for up to
30 seconds (Winston LFP can surge to 20C!) and 2C-3C
continuous discharge, it makes sense to me to design a
protection system that can't utilize that capability.
Our LFMP battery has an external CPU that I can
program. We also use external high current relays for
the protective circuits so the full load of the
inverter can be put to use.</div>
<div><br>
</div>
<div>With a LFP battery bank of 48 volts and 400AH,
somewhat small for off grid, the battery can operate
continuously at 1200 amps or about 60kW output and
surge to 4000 amps/600kW. This obviously is way beyond
the demand capability of the inverter(s). A quick look
at the SI6048 data sheet shows maximum AC current is
11kW for 3 seconds.</div>
<div><br>
</div>
<div>I am glad you noticed the extremely low voltage sag
under load. This feature means lower current which
should translate to longer life for inverters. It also
means starting loads that you can’t with a similar
sized lead acid battery. A 1C load typically has only
0.2 volt sag. For 48 volt systems, this means
maintaining 51.2 volts throughout the full battery
use. In fact, a 1C load will still only have 0.2 volt
drop until about 90% discharged. Simply amazing.</div>
<div><br>
</div>
<div>Larry Crutcher</div>
<div><br>
<br>
<div>
<div>On Sep 17, 2014, at 10:15 PM, William Miller
<<a moz-do-not-send="true" href="mailto:william@millersolar.com">william@millersolar.com</a>>
wrote:</div>
<br class="Apple-interchange-newline">
<div>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<meta name="Generator" content="Microsoft Word 14
(filtered medium)">
<!--[if !mso]><style>v\:* {behavior:url(#default#VML);}
o\:* {behavior:url(#default#VML);}
w\:* {behavior:url(#default#VML);}
.shape {behavior:url(#default#VML);}
</style><![endif]-->
<style><!--
/* Font Definitions */
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:Tahoma;
panose-1:2 11 6 4 3 5 4 4 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Times New Roman","serif";}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
p
{mso-style-priority:99;
mso-margin-top-alt:auto;
margin-right:0in;
mso-margin-bottom-alt:auto;
margin-left:0in;
font-size:12.0pt;
font-family:"Times New Roman","serif";}
tt
{mso-style-priority:99;
font-family:"Courier New";}
p.MsoAcetate, li.MsoAcetate, div.MsoAcetate
{mso-style-priority:99;
mso-style-link:"Balloon Text Char";
margin:0in;
margin-bottom:.0001pt;
font-size:8.0pt;
font-family:"Tahoma","sans-serif";}
span.BalloonTextChar
{mso-style-name:"Balloon Text Char";
mso-style-priority:99;
mso-style-link:"Balloon Text";
font-family:"Tahoma","sans-serif";}
span.EmailStyle22
{mso-style-type:personal;
font-family:"Arial","sans-serif";
color:#1F497D;}
span.EmailStyle23
{mso-style-type:personal-reply;
font-family:"Arial","sans-serif";
color:#1F497D;}
.MsoChpDefault
{mso-style-type:export-only;
font-size:10.0pt;}
@page WordSection1
{size:8.5in 11.0in;
margin:1.0in 1.0in 1.0in 1.0in;}
div.WordSection1
{page:WordSection1;}
/* List Definitions */
@list l0
{mso-list-id:342125673;
mso-list-template-ids:8186644;
mso-list-style-priority:99;
mso-list-style-name:Test;}
@list l0:level1
{mso-level-tab-stop:none;
mso-level-number-position:left;
margin-left:1.0in;
text-indent:-.5in;}
@list l0:level2
{mso-level-number-format:alpha-lower;
mso-level-tab-stop:none;
mso-level-number-position:left;
margin-left:1.5in;
text-indent:-.5in;}
@list l0:level3
{mso-level-number-format:roman-lower;
mso-level-tab-stop:none;
mso-level-number-position:right;
margin-left:2.0in;
text-indent:-.5in;}
@list l0:level4
{mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-.25in;}
@list l0:level5
{mso-level-number-format:alpha-lower;
mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-.25in;}
@list l0:level6
{mso-level-number-format:roman-lower;
mso-level-tab-stop:none;
mso-level-number-position:right;
text-indent:-9.0pt;}
@list l0:level7
{mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-.25in;}
@list l0:level8
{mso-level-number-format:alpha-lower;
mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-.25in;}
@list l0:level9
{mso-level-number-format:roman-lower;
mso-level-tab-stop:none;
mso-level-number-position:right;
text-indent:-9.0pt;}
ol
{margin-bottom:0in;}
ul
{margin-bottom:0in;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
<div link="blue" vlink="purple" lang="EN-US">
<div class="WordSection1"><p class="MsoNormal"><span style="font-family:"Arial","sans-serif";color:#1F497D">Larry:<o:p></o:p></span></p>
<div><span style="font-family:"Arial","sans-serif";color:#1F497D"> </span><br class="webkit-block-placeholder">
</div><p class="MsoNormal"><font face="Arial,
sans-serif"><font color="#1f497d">…</font><font color="#1f497d" size="3">...</font></font><span style="color: rgb(31, 73, 125);
font-family: Arial, sans-serif; font-size:
12pt;">The internal battery management
system will allow them to disconnect under
surge loads, just when you need your
batteries to stay connected. I will be
conversing with the manufacturer to learn
more about them.</span></p>
<div><span style="font-family:"Arial","sans-serif";color:#1F497D"> </span><br class="webkit-block-placeholder">
</div><p class="MsoNormal"><span style="font-family:"Arial","sans-serif";color:#1F497D">William<o:p></o:p></span></p>
<div><span style="font-family:"Arial","sans-serif";color:#1F497D"> </span><br class="webkit-block-placeholder">
</div>
<div><br></div></div></div></div></div></div></blockquote></div></div></div></div></blockquote></div></div></div></div></body></html>