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<DIV><SPAN class=680222723-03082008><FONT face=Arial color=#0000ff
size=2>Jay,</FONT></SPAN></DIV>
<DIV><SPAN class=680222723-03082008><FONT face=Arial color=#0000ff size=2>You're
right about leaving off the post at the bottom - whoops. It's at the bottom
here.</FONT></SPAN></DIV>
<DIV><SPAN class=680222723-03082008><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=680222723-03082008><FONT face=Arial color=#0000ff size=2>About
voltage drop: I meant only that by running the array at a higher voltage than
the batteries, there could never be sufficient hot-weather and undersized-wire
voltage drop to prevent the array from exceeding the EQ voltage of the
batteries. This is most often a potential problem with 12V systems. I mentioned
it only to eliminate it as a possible cause of this
situation.</FONT></SPAN></DIV>
<DIV><SPAN class=680222723-03082008><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=680222723-03082008><FONT face=Arial color=#0000ff size=2>The
Surrette Tech Bulletin 614 is available for download at <A
href="http://surrette.com/files/BU-RS-614.pdf">http://surrette.com/files/BU-RS-614.pdf</A>.
My understanding is that this bulletin is the direct result of the complaints on
this list about two years ago about Surrette battery performance and life.
</FONT></SPAN></DIV>
<DIV><SPAN class=680222723-03082008><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=680222723-03082008><FONT face=Arial color=#0000ff
size=2>Allan</FONT></SPAN></DIV>
<DIV><SPAN class=680222723-03082008><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV></DIV>
<DIV class=OutlookMessageHeader lang=en-us dir=ltr align=left><FONT face=Tahoma
size=2>-----Original Message-----<BR><B>From:</B> jay peltz
[mailto:jay@asis.com] <BR><B>Sent:</B> Sunday, August 03, 2008 1:41
PM<BR><B>To:</B> Allan Sindelar<BR><B>Subject:</B> Fwd: [RE-wrenches] Surrette
Battery Question<BR><BR></FONT></DIV>HI Allan,
<DIV><FONT face=Arial color=#0000ff size=2></FONT><BR></DIV>
<DIV>You mention about a Surrette tech bull<SPAN
class=680222723-03082008>eti</SPAN>n, I can't seem to find it?<SPAN
class=680222723-03082008> </SPAN>Can you tell me where it might be on their
site?</DIV>
<DIV><BR></DIV>
<DIV>Also I"m curious about you saying that hot modules isn't going to affect
voltage drop.</DIV>
<DIV>Sure it will. If the wire is upsized for the lower voltages from hot
weather, then you've compensated for it, but there is still added voltage
drop.</DIV>
<DIV><BR></DIV>
<DIV>And about the adding new panels to old? I didn't see the link/post at the
bottom?</DIV>
<DIV><SPAN class=680222723-03082008> T</SPAN>hanks,<SPAN
class=680222723-03082008> j</SPAN>ay<SPAN class=680222723-03082008><FONT
face=Arial color=#0000ff size=2> </FONT></SPAN></DIV>
<DIV><SPAN class=680222723-03082008></SPAN> </DIV>
<DIV><SPAN class=680222723-03082008><FONT face=Arial color=#0000ff size=2>OK,
the story,</FONT></SPAN></DIV>
<DIV><SPAN class=680222723-03082008><FONT face=Arial color=#0000ff size=2>This
client had started off-grid in the early nineties with a tight budget. He and
his wife would add modules as they could afford them, usually used. The built a
homemade tracker with a Wattsun SA controller and two linear actuators,
using a DPDT momentary switch to adjust elevation seasonally. Over time the
tracker filled out with eight Arco 16-2000s, nine Carrizo (Arco) M52L 5V
Quad-Lams, two BP 275s, and two old square whatsises with 2" cells from the
seventies. </FONT></SPAN></DIV>
<DIV><SPAN class=680222723-03082008><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=680222723-03082008></SPAN><SPAN class=680222723-03082008><FONT
face=Arial color=#0000ff size=2>Eventually their income increased and their
house and house loads got bigger. </FONT></SPAN><SPAN
class=680222723-03082008><FONT face=Arial color=#0000ff size=2>They
asked us to upgrade their array, which eventually led to the 8 160W
modules I added on a pole-top array. There were several catches,
though:</FONT></SPAN></DIV>
<DIV><SPAN class=680222723-03082008><FONT face=Arial color=#0000ff size=2>1.
They wanted to keep as much as possible of the original "democracy tracker" in
operation;</FONT></SPAN></DIV>
<DIV><SPAN class=680222723-03082008><FONT face=Arial color=#0000ff size=2>2. The
house had grown over the years, and the existing tracker had to be moved 50'
farther away;</FONT></SPAN></DIV>
<DIV><SPAN class=680222723-03082008><FONT face=Arial color=#0000ff size=2>3. The
balance-of-system was still in the original basement, now inaccessible from the
outside, as the house had been expanded bit by bit in all directions.
</FONT></SPAN></DIV>
<DIV><SPAN class=680222723-03082008><FONT face=Arial color=#0000ff size=2>4. The
#2 (or 2/0, I can't recall) USE copper array input wires had been built over and
couldn't be replaced; we had to use them.</FONT></SPAN></DIV>
<DIV><SPAN class=680222723-03082008><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=680222723-03082008><FONT face=Arial color=#0000ff size=2>We
dismantled the tracker and moved the pole (yep, lifted pole, concrete and all
and set it in a new, larger hole with more concrete). We put a 3R j-box where
the old pole had been and trenched to the new locations. After playing with
different calculations, we changed the old tracked array as follows:
</FONT></SPAN></DIV>
<DIV><SPAN class=680222723-03082008><FONT face=Arial color=#0000ff size=2>1. We
added two BP 380s (the closest we could get then to the older 275s) and wired
them as one 48V string;</FONT></SPAN></DIV>
<DIV><SPAN class=680222723-03082008><FONT face=Arial color=#0000ff size=2>2. We
dumped the whatsises, which had low output;</FONT></SPAN></DIV>
<DIV><SPAN class=680222723-03082008><FONT face=Arial color=#0000ff size=2>3. Now
I'm trying to remember: I think I wired the four 16-2000s (originally 2.2A at
12V) in parallel, then wired this set of four in series with the nine Quad-Lams
(think of M52Ls, originally used in the Carrisa Plains utility central power
plant in California from 1984-1989 or so, as similar to 16-2000s but with the 3
rows of cells wired in parallel, to make about 7A at 4 1/2V nominal. That's why
they're called Quad-Lams: it took four in series to charge a 12V battery).
</FONT></SPAN></DIV>
<DIV><SPAN class=680222723-03082008><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=680222723-03082008><FONT face=Arial color=#0000ff size=2>So we
ended up with a 17-module array wired at 48V nominal, tied in with the new 48V
array. What made it so special, other than that it's the only 17-module array I
ever built? When we were all done and it was charging the 24V battery through
the MX60, I alternately turned each array off and let the MX60 find its MPPT
voltage: the two arrays were within one volt of each other. We got it
right, and I have always been especially pleased with that
job.</FONT></SPAN></DIV>
<DIV><SPAN class=680222723-03082008><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=680222723-03082008><FONT face=Arial color=#0000ff size=2>That's
all. </FONT></SPAN></DIV>
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