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<div class="moz-cite-prefix">OK, a bit more:<br>
The line diagram I was referencing was dated 5/1/2010. A later
diagram from a Powerpoint given at last year's NABCEP CE
conference shows a "MagNet" AC diversion controller. It allows AC
diversion loads and three-stage charging. No mention of temp comp.<br>
<br>
Magnum needs to weigh in on this.<br>
Allan<br>
<br>
<div class="moz-signature">
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<title></title>
<font face="Times New Roman, Times, serif"><b>Allan Sindelar</b></font><br>
<small><a 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>
Founder and Chief Technology Officer<br>
<b>Positive Energy, Inc.</b><br>
3209 Richards Lane (note new address)<br>
Santa Fe, New Mexico 87507<br>
<b>505 424-1112</b><br>
<a href="http://www.positiveenergysolar.com/"
target="_blank"><u>www.positiveenergysolar.com</u></a><o:p></o:p></span></font>
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On 3/7/2013 3:00 PM, Drake wrote:<br>
</div>
<blockquote
cite="mid:20130307220156.5C9EDFE065@homiemail-a56.g.dreamhost.com"
type="cite">
Hello Wrenches,<br>
<br>
I had an unexpected glitch in AC coupling a Magnum 4024 PAE
inverter. The system utilizes AGM batteries, which (according to
Concorde tech support) have a very strict upper voltage limit.<br>
<br>
The relay used to stop the current input from the direct grid tie
inverter, when battery voltage is high, is controlled by a
Morningstar
Relay Driver. The relay driver is set to shut off the charge at
28.8 volts.<br>
<br>
The charger on the Magnum is set to charge the batteries to 28.6
volts. <br>
<br>
The plan was to be able to charge batteries from the Magnum
without
tripping the AC connection between the grid tie inverter to the
grid. The Magnum should charge to 28.6 volts, 0.2 volts below the
relay driver's programmed trigger point. <br>
<br>
There is one catch to using this approach. The Magnum inverter has
a
remote temperature sensor in the battery bank. The relay driver is
not
temperature corrected. Therefore, when the batteries are cold, the
charging voltage goes up in the Magnum. This higher voltage trips
the relay controlled by the driver, and disconnects the grid tie
inverter
from the grid. <br>
<br>
I've played with the voltage set points, but the charge voltage on
the
Magnum would be too low for good battery maintenance. If these
were
liquid electrolyte batteries, I'd crank up the voltage on the
relay
driver. Since they are AGM batteries, it doesn't seem like a good
idea to do that. <br>
<br>
The work around for this at present is to;
<ul>
<li>Charge batteries at night in the winter
</li>
<li>No problem is expected in the summer
</li>
</ul>
The batteries are in an insulated box in a shed connected to the
house. The inside of the battery box has a screened hole that is
supposed
to allow heated air into the box. This vent doesn't keep the
batteries warm enough to prevent the problem. <br>
<br>
Is there a temperature sensitive, voltage controlled relay or
diver
available? Has anyone used a temperature bulb with the relay
driver
in a way that could solve this problem? Has anyone else come up
against
this issue, and if so, what was your solution?<br>
<br>
Thanks,<br>
<br>
Drake <br>
<br>
<br>
<a moz-do-not-send="true" name="_MailAutoSig"></a>Drake Chamberlin<br>
<i>Athens Electric LLC<br>
OH License 44810<br>
CO License 3773<br>
NABCEP Certified Solar PV Installer<br>
740-448-7328<br>
</i><a moz-do-not-send="true" href="http://athens-electric.com/">http://athens-electric.com/</a>
<br>
<br>
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