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Dave,<br>
My response is only part of the answer, but may help with your
system setup. Both the SB50 and the FM60 have the ability to limit
the absorption time, although by different methods. This may serve
as a key setting to reduce gassing and water use when the homeowners
are away.<br>
<br>
With the SB50, you can adjust the float transition current to a
allow the switch the batteries from acceptance (Blue Sky's term for
absorption) into float sooner. The default recommendation is 2% of
battery capacity per the manual; perhaps 3% would allow it to
transition sooner. The FM60 has a setting to allow transition to
float at a set current - that is, as long as the voltage is at the
bulk/absorption setpoint (suggesting that the batteries are nearly
full), rather than staying in absorption for the entire timed
absorption period, if the current necessary to maintain absorption
voltage drops below this threshold (of typically around 2% of
battery capacity, or about 44 amps in your case) the controller will
go into float. My understanding is that this is specifically to
reduce daily absorption time when batteries are lightly cycled, as
in this case.<br>
<br>
What I don't know is how these two very different controllers
(digital vs. analog, among other differences) will work as a team
together. Other Wrenches may have more experience. My idea is to set
the FTC on the SB50 high so that it will transition first, allowing
the FM80 to regulate final transition. Maybe instead set the SB50 to
a slightly lower bulk/acceptance setpoint voltage, so that the SB50
drops out a bit sooner and the FM80 completes the daily charge.<br>
Allan<br>
<br>
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<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>
<b>Positive Energy, Inc.</b><br>
3201 Calle Marie<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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<br>
On 8/2/2011 3:49 PM, Dave Palumbo wrote:
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<p class="MsoNormal">Our go to guy at Trojan, Ron Parades, is
evidently gone. That’s what they said at his old phone
extension at Trojan. I left a message for tech support there
and have not heard back as of yet.<o:p></o:p></p>
<p class="MsoNormal"><span style="font-size: 8pt;"><o:p> </o:p></span></p>
<p class="MsoNormal">Is there another Trojan Tech person to
specifically ask for now? And is there one on this list
helping out as Ron did previously?<o:p></o:p></p>
<p class="MsoNormal"><span style="font-size: 8pt;"><o:p> </o:p></span></p>
<p class="MsoNormal">I have a question on the Trojan RE Series
charging voltage settings. I know the specific gravity is
lower on this series and the bulk charge voltage is
correspondingly lower than the old L-16’s.<o:p></o:p></p>
<p class="MsoNormal"><span style="font-size: 8pt;"><o:p> </o:p></span></p>
<p class="MsoNormal">I have an off grid system for a remote home
where the client is only there from June through October. He
has 1,560 Watts of solar and a new battery bank rated at 2,220
AH at 12 volts (12 L-16 RE-2V batteries). <o:p></o:p></p>
<p class="MsoNormal">That is a charge rate in the C/20 range.
The homeowner uses the system reasonable hard when they are
there but during the winter the load is only 15AH per day for
a low voltage security system.<o:p></o:p></p>
<p class="MsoNormal"><span style="font-size: 8pt;"><o:p> </o:p></span></p>
<p class="MsoNormal">He has previously serviced his Rolls
CH-375’s (1,400AH with 450 Watts of PV on that system, about a
C/33 rate) in October before leaving for 7 months and has not
had a problem with the battery electrolyte boiling off too
much over that time period. He got 10 years out of the Rolls
batteries using it in this way. The charge voltage for that
system was 14.6 through a Solar Boost 50.<o:p></o:p></p>
<p class="MsoNormal"><span style="font-size: 8pt;"><o:p> </o:p></span></p>
<p class="MsoNormal">The new system will have 1,110 Watts
charging through a Out Back FM 80 alongside the original array
on the Solar Boost for the total of 1,560 Watts of PV.<o:p></o:p></p>
<p class="MsoNormal"><span style="font-size: 8pt;"><o:p> </o:p></span></p>
<p class="MsoNormal">I am thinking of charging at 14.6 Bulk with
a two hour absorption time period in the summer and then
changing it for the 7 month period when the system is lightly
used. <o:p></o:p></p>
<p class="MsoNormal"><span style="font-size: 8pt;"><o:p> </o:p></span></p>
<p class="MsoNormal">My question is, how low should I set the
two charge controllers for winter/spring use to minimize water
consumption? I’m thinking of 14.2 or 14.3 Volts, with a
reduced absorption time of one hour. <o:p></o:p></p>
<p class="MsoNormal">And what should the float voltage setting
be? The batteries are in a basement that is kept at about 55
degrees. There is temperature compensation on the battery
charging.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thank you,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">David Palumbo<o:p></o:p></p>
<p class="MsoNormal">Independent Power LLC <o:p></o:p></p>
<p class="MsoNormal">462 Solar Way Drive<o:p></o:p></p>
<p class="MsoNormal">Hyde Park, VT 05655<b><o:p></o:p></b></p>
<p class="MsoNormal"><b><i><a class="moz-txt-link-abbreviated" href="http://www.independentpowerllc.com">www.independentpowerllc.com</a> <o:p></o:p></i></b></p>
<p class="MsoNormal">NABCEP Certified PV Installer<o:p></o:p></p>
<p class="MsoNormal">Vermont Solar Partner<o:p></o:p></p>
<p class="MsoNormal">23 Years Experience, (802) 888-7194 <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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