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<p><font size=2 face=Arial><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Here
is what I am thinking of doing: I want to remove the string of batteries with
the bad cell completely from the system. That gives me an increase in my bulk
charge current for the remaining strings and reduces the number of parallel
strings. I also want 4 times a year to adjust the charge parameters to match
the seasonal condition including tacking on as much absorption time as
feasible.</span></font><o:p></o:p></p>
<p><font size=2 face=Arial><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>So
what to do with all those extra batteries? Can I cut them all out into the
individual cells, drain the acid and keep them in storage, available to replace
bad cells in the future?</span></font><o:p></o:p></p>
<p class=MsoNormal><font size=4 color=black face=Calibri><span
style='font-size:14.0pt;font-family:"Calibri","sans-serif";color:black'>Mark,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=4 color=black face=Calibri><span
style='font-size:14.0pt;font-family:"Calibri","sans-serif";color:black'>Do not
remove and drain the cells, they will be ruined soon if you do. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=4 color=black face=Calibri><span
style='font-size:14.0pt;font-family:"Calibri","sans-serif";color:black'>How
about replacing the bad cell with a new one? This is done all the time on the
forklift industry. It will extend the life of the bank and keep the battery
size the same as originally planned.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=4 color=black face=Calibri><span
style='font-size:14.0pt;font-family:"Calibri","sans-serif";color:black'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=4 color=black face=Calibri><span
style='font-size:14.0pt;font-family:"Calibri","sans-serif";color:black'>I would
move the absorb setting to as long as you can on the generator and on the charge
controllers also.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=4 color=black face=Calibri><span
style='font-size:14.0pt;font-family:"Calibri","sans-serif";color:black'>I
assume these cells are welded together with lead straps. Drill them off and weld
In another cell. All done, back to normal…<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=4 color=black face=Calibri><span
style='font-size:14.0pt;font-family:"Calibri","sans-serif";color:black'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=4 color=black face=Calibri><span
style='font-size:14.0pt;font-family:"Calibri","sans-serif";color:black'>Bob
Ellison <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=4 color=black face=Calibri><span
style='font-size:14.0pt;font-family:"Calibri","sans-serif";color:black'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=4 color=black face=Calibri><span
style='font-size:14.0pt;font-family:"Calibri","sans-serif";color:black'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:"Tahoma","sans-serif";font-weight:bold'>From:</span></font></b><font
size=2 face=Tahoma><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>
re-wrenches-bounces@lists.re-wrenches.org
[mailto:re-wrenches-bounces@lists.re-wrenches.org] <b><span style='font-weight:
bold'>On Behalf Of </span></b>Mark Frye<br>
<b><span style='font-weight:bold'>Sent:</span></b> Monday, June 21, 2010 11:21
PM<br>
<b><span style='font-weight:bold'>To:</span></b> 'RE-wrenches'<br>
<b><span style='font-weight:bold'>Subject:</span></b> [RE-wrenches] For Big
Bank Off Grid System Connoisseurs<o:p></o:p></span></font></p>
</div>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
<p><font size=2 face=Arial><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Here
are details of a system I am working with:</span></font> <o:p></o:p></p>
<p><font size=2 face=Arial><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>2
hours south of Sacramento CA and west into the coast range for 5 miles and 30
minutes on a rough dirt road is an improvement. The improvement consists of a
large main house, 2 separate guest cabins, and a four car garage, all built out
of logs from British Columbia. Out back and up the hill is a power house.
There is a well with bad water and a satellite telephone, no PG&E. Most of
the time no one is around, but a few times a year, folks show up and have a
party.</span></font><o:p></o:p></p>
<p><font size=2 face=Arial><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>This
off-grid power system consists of 16 - Enersys 1690 AH @ 20 hour HUP 12V
forklift batteries. The batteries are arranged in 4 strings of 4 batteries
each.</span></font><o:p></o:p></p>
<p><font size=2 face=Arial><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>There
are 10 - Outback VFX3648 inverters in a 2 phase stack.</span></font> <o:p></o:p></p>
<p><font size=2 face=Arial><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>There
is a Kohler REGZ 30 KVA propane powered generator.</span></font> <o:p></o:p></p>
<p><font size=2 face=Arial><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Also
included is about 5 KW worth of Astropower 120 modules plugged into 2 MX60s.</span></font>
<o:p></o:p></p>
<p><font size=2 face=Arial><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>A
Trimetric TM-2020 watches the charge flowing in and out of the battery bank.</span></font>
<o:p></o:p></p>
<p><font size=2 face=Arial><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>The
system has run without interruption or major problem for 6 years. However,
recently we have had our first major service on the generator, our first smoked
inverter, and we have a dead cell in one of the batteries.</span></font><o:p></o:p></p>
<p><font size=2 face=Arial><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Besides
the occasionally high demand use events, the stand by conditions run along two
seasonal veins: In summer the main demand besides the usual refrigerator and
alarm system is pumping and treating irrigation water; In the winter heating
systems run to keep the buildings warm.</span></font><o:p></o:p></p>
<p><font size=2 face=Arial><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>The
contribution of the PV is secondary. On a recent visit the 2 MX's generated
about 30KWH of energy in a day. However, this significant contribution to the
system is generally not sufficient to completely offset the summer standby
loads and the generator will run according to it's AGS setting about once every
2 - 3 weeks. In the winter the generator runs more often.</span></font><o:p></o:p></p>
<p><font size=2 face=Arial><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>I
have the AGS running on Volt Start and it appears that the generator will run
after somewhere between 2000 and 3000 Ah have been removed from the bank. Once
started the charge settings are bulk to 60V, absorb for 12 minutes and
shut-off. In the winter the chargers can run at almost their full power and
deliver about 360 A during the bulk phase. In the summer the chargers fold back
significantly due to heat in the power house. This folded-back charge rate is
what has dictated the charge regime. Not wanting to run the generator at reduce
capacity for extended lengths of time means getting the voltage up through the
bulk phase as best as possible in the summer and then bailing on the absorption
phase. This has been the one-size-fits-all setting that has been running all
year round for 6 years.</span></font><o:p></o:p></p>
<p><font size=2 face=Arial><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Recently
I checked the specific gravity of the batteries at the end of the normal charge
cycle and got 1260 in most cells. Interestingly enough I then put in an
additional 1200 Ah and the sp didn't budge.</span></font><o:p></o:p></p>
<p><font size=2 face=Arial><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>My
sense is that the bank, on average, has been getting charging up to about
80-85% of full and then discharging to about 50-55% of full.</span></font><o:p></o:p></p>
<p><font size=2 face=Arial><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>So
there you have it. Perhaps a lamentable state of affairs, but the state of
affairs none the less.</span></font> <o:p></o:p></p>
<p><font size=2 face=Arial><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>I
know there are many many possibilities for this system. The owner would prefer
to manage on-going maintenance costs as opposed to making significant capital
expenditures on major system reconfigurations.</span></font><o:p></o:p></p>
<p><font size=2 face=Arial><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Here
is what I am thinking of doing: I want to remove the string of batteries with
the bad cell completely from the system. That gives me an increase in my bulk
charge current for the remaining strings and reduces the number of parallel
strings. I also want 4 times a year to adjust the charge parameters to match
the seasonal condition including tacking on as much absorption time as
feasible.</span></font><o:p></o:p></p>
<p><font size=2 face=Arial><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>So
what to do with all those extra batteries? Can I cut them all out into the
individual cells, drain the acid and keep them in storage, available to replace
bad cells in the future?</span></font><o:p></o:p></p>
<p><font size=2 face=Arial><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Any
advice?</span></font> <br>
<font face=Arial><span style='font-family:"Arial","sans-serif"'> </span></font>
<br>
<font size=2 face=Arial><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Mark
Frye</span></font> <br>
<font size=2 face=Arial><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Berkeley
Solar Electric Systems</span></font> <br>
<font size=2 face=Arial><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>303
Redbud Way</span></font> <br>
<font size=2 face=Arial><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Nevada
City, CA 95959</span></font> <br>
<font size=2 face=Arial><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>(530)
401-8024</span></font> <br>
<a href="http://www.berkeleysolar.com"><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:"Arial","sans-serif"'>www.berkeleysolar.com</span></font></a><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'> </span></font>
<o:p></o:p></p>
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