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<div class="moz-cite-prefix">I think if we started over fresh with
our lead acid battery system designs, we would find we should have
the same Battery management system requirements that you have
mentioned. Those are all problems that plague lead acid as well.<br>
<pre class="moz-signature" cols="72">R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760</pre>
On 9/15/2014 8:08 PM, <a class="moz-txt-link-abbreviated" href="mailto:Jarmo.Venalainen@schneider-electric.com">Jarmo.Venalainen@schneider-electric.com</a>
wrote:<br>
</div>
<blockquote
cite="mid:OF4EFDEBEF.F6D492B1-ON88257D55.000844F2-88257D55.000BC618@US.Schneider-Electric.com"
type="cite"><font face="sans-serif" size="2">Hi:</font>
<br>
<br>
<font face="sans-serif" size="2">We've done some testing and
operation
of Lion battery banks in the 10 kWh range with our inverter
chargers and
so far the most important findings are:</font>
<br>
<br>
<font face="sans-serif" size="2">1. The battery pack must have its
own
battery management system to:</font>
<br>
<font face="sans-serif" size="2">a. regulate the individual cell
voltages
during charge and discharge</font>
<br>
<font face="sans-serif" size="2">b. balance the cell voltages
during
charge and discharge</font>
<br>
<font face="sans-serif" size="2">c. adjust cell charging voltages
due
to temperature variations</font>
<br>
<font face="sans-serif" size="2">d. not provide a continuous float
voltage
to the battery bank</font>
<br>
<font face="sans-serif" size="2">d. provide a built in safety
cutoff
disconnect, which turns off the current if for any reason either
the charge
or discharge current is too high.</font>
<br>
<br>
<font face="sans-serif" size="2">A series string of Lion cells,
without
the battery management system functions above is very likely to
result
in damaged cells or worse. The most likely mechanism which
ultimately
causes damage is individual cell temperature or cell to cell
voltage imbalance.
</font>
<br>
<br>
<font face="sans-serif" size="2">2. The inverter system must be
designed
so that the inverter never draws so much current that the
current limit
circuit in the battery bank is triggered. </font>
<br>
<br>
<font face="sans-serif" size="2">3. It may be necessary to adjust
the
current limit circuit as they typically respond within
milli-seconds and
may be triggered on simple power up as the inverter cap bank
charges up.</font>
<br>
<br>
<font face="sans-serif" size="2">4. When working with Lion, the
inverter/charger
should be configured so that it is a simple current limited
voltage source
when in charge mode. The built in battery management system
should
take care of the required charge cycle operation.</font>
<br>
<br>
<font face="sans-serif" size="2">5. Whether the pack is LiFePO4,
Lion
polymer or other does not appear to be as important as a having
a reputable
brand and more importantly a well designed built in battery
management
system.</font>
<br>
<br>
<font face="sans-serif" size="2">The short version is that lead
acid
cells are amazingly forgiving with regards charging and
discharging voltages,
currents and temperatures. Lion cells on the other hand are
amazingly
sensitive and going out of bounds on any of these can and will
cause irreparable
damage. </font>
<br>
<br>
<font face="sans-serif" size="2">Given the sensitivity, it doesn't
make
sense to take on responsibility for Lion battery management.</font>
<br>
<br>
<font face="sans-serif" size="2">Management of that sensitivity
and responsibility
is best left to the battery bank manufacturer. </font>
<br>
<br>
<font face="sans-serif" size="2">JARMO<br>
</font><font color="#008000" size="3">_____________________________________________________________________________________</font><font
size="3">
<br>
</font><font face="Arial" size="1"><b><br>
Jarmo Venalainen</b> | </font><font color="#008000"
face="Arial" size="1"><b>
Schneider Electric </b></font><font face="Arial" size="1"><b>
| Solar
Business</b> | <b>CANADA</b> | <b>Training &
Development Specialist - Senior</b> <b><br>
Phone:</b> +604-422-2528 | <b>Fax:</b> +604-420-1591 |
<b>Mobile:</b> +604-505-0291 <b><br>
Email:</b> </font><a moz-do-not-send="true"
href="mailto:jarmo.venalainen@schneider-electric.com"><font
color="blue" face="Arial" size="1"><u>jarmo.venalainen@schneider-electric.com</u></font></a><font
face="Arial" size="1">
| <b>Site:</b></font><a moz-do-not-send="true"
href="http://www.sesolar.com/" target="_blank"><font
color="blue" face="Arial" size="1"><u>
www.SEsolar.com</u></font></a><font face="Arial" size="1">
|
<b>Address:</b> 3700 Gilmore Way, Burnaby, BC V5G4M1 <br>
</font><font color="blue" face="Arial" size="1"><u><br>
</u></font><a moz-do-not-send="true"
href="http://%20www.sesolar.com/"><img
src="cid:part3.04080304.02030504@solarray.com"></a><font
face="Arial" size="1"><br>
*** Please consider the environment before printing this e-mail</font><font
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<br>
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<br>
<br>
<br>
<table width="100%">
<tbody>
<tr valign="top">
<td><font color="#5f5f5f" face="sans-serif" size="1">From:</font>
</td>
<td><font face="sans-serif" size="1">"William Miller"
<a class="moz-txt-link-rfc2396E" href="mailto:william@millersolar.com"><william@millersolar.com></a></font>
</td>
</tr>
<tr valign="top">
<td><font color="#5f5f5f" face="sans-serif" size="1">To:</font>
</td>
<td><font face="sans-serif" size="1">"RE-wrenches"
<a class="moz-txt-link-rfc2396E" href="mailto:re-wrenches@lists.re-wrenches.org"><re-wrenches@lists.re-wrenches.org></a>,
</font>
</td>
</tr>
<tr valign="top">
<td><font color="#5f5f5f" face="sans-serif" size="1">Date:</font>
</td>
<td><font face="sans-serif" size="1">09/15/2014 04:27 PM</font>
</td>
</tr>
<tr valign="top">
<td><font color="#5f5f5f" face="sans-serif" size="1">Subject:</font>
</td>
<td><font face="sans-serif" size="1">[RE-wrenches] LiFePo4</font>
</td>
</tr>
<tr valign="top">
<td><font color="#5f5f5f" face="sans-serif" size="1">Sent
by:</font>
</td>
<td><font face="sans-serif" size="1">"RE-wrenches"
<a class="moz-txt-link-rfc2396E" href="mailto:re-wrenches-bounces@lists.re-wrenches.org"><re-wrenches-bounces@lists.re-wrenches.org></a></font></td>
</tr>
</tbody>
</table>
<br>
<hr noshade="noshade">
<br>
<br>
<br>
<font face="Arial" size="3">Wrenches:</font>
<br>
<font face="Arial" size="3"> </font>
<br>
<font face="Arial" size="3">Does anyone have any experience with
Lithium
Ferrous Phosphate cells? What are your experiences? I am
looking
at an installation tomorrow and would like some input.</font>
<br>
<font face="Arial" size="3"> </font>
<br>
<font face="Arial" size="3">Thanks in advance.</font>
<br>
<font face="Arial" size="3"> </font>
<br>
<font face="Arial" size="3">William Miller</font>
<br>
<font face="Arial" size="3"> </font>
<br>
<img src="cid:part5.09060700.09000704@solarray.com" alt="Gradient
Cap_mini"><font face="Arial" size="2"><br>
Lic 773985</font><font color="blue" face="Arial" size="2"><u><br>
</u></font><a moz-do-not-send="true"
href="http://www.millersolar.com/"><font color="blue"
face="Arial" size="2"><u>millersolar.com</u></font></a><font
face="Arial" size="2"><br>
805-438-5600</font>
<br>
<font face="Calibri" size="2"> </font>
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