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<div class="moz-cite-prefix">I thought the relays on the SWs were
sealed, so visible arcing sounds bad. Are you sure its not a
loose connection?<br>
Also on the batteries, anytime I've ever seen someone replace just
a couple of cells in a bank that old, it never ended well. It was
like that gopher stomping game, and you hit one problem, and then
another pops up right after.....<br>
We need some kind of financing program for battery replacements,
so that people can get what they really need: a whole new set.<br>
That very situation, is why I quit doing as many single series
strings: one or two cells fail, and the whole system goes. <br>
In this same situation with 2 strings, you create a single string
of your strongest cells to limp the customer along, until they can
afford to replace the set. As cells go down, you keep pulling in
replacements from the retired string. This would be a great time
to take a few of the best used cells from another aging set on
another system that is getting replaced.<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 11/18/2013 5:01 PM, Allan Sindelar wrote:<br>
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type="cite">
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Wrenches,<br>
A longtime off grid customer with a 1997-era Trace SW4024 and a
Kohler 8.5RMY backup generator (with 1,800 hours over 16 years)
has never had an inverter failure, but requested my assistance
with a recent development. His generator has been set up on
automatic operation using standard Trace voltage, quiet time and
load-start program parameters. When it was called to run, it would
charge to 29.6 V with a one-hour absorption, then shut off. This
has worked well until recently. The automatic operation includes a
cool-down and the modest absorption means that the AC input
current at shutdown is going to be pretty low.<br>
<br>
Recently he called me because his generator was starting more
frequently and running for longer duration. Of course, I
immediately suspected the batteries, which are ten-year old 5000
series Surrette 4KS-25PS cells. Upon checking I found two weak
cells, which would explain the inability of the batteries to reach
full voltage and shut off after absorption. I will be replacing
these two cells, which fortunately are both within the same red
polypropylene case, as our only option, as the homeowner's budget
won't allow replacement of the whole set. As a single string, the
two new cells should play reasonably well with the old cells for a
few more years.<br>
<br>
Because of this, the homeowner had recently shut off the generator
at night using the buttons on the inverter, and when he did this
he saw a spark flash from inside the inverter on the AC end. I was
able to duplicate the flash, which I assume to be the AC2 input
relay. The AC2 In setpoint is set to maximum 35A AC. Until the
failed cells are replaced, I have advised the homeowner to
manually control the generator at the generator, using its AC
output breaker to disconnect the current to the inverter before
the 108V AC default input voltage threshold causes the inverter AC
input relay to unlatch under load. While the SW latches while
unloaded and then ramps up input current, I don't believe that it
can reduce input current to zero before unlatching when shutting
down. <br>
<br>
My guess is that after 15 years of flawless performance, the relay
contacts have pitted enough to cause arcing at disconnect, and if
not addressed, the relay on the AC board will eventually fail. As
AC relay boards these days are likely made out of unobtanium, I'd
rather avoid this failure.<br>
<br>
So my questions, please: <br>
1. Have I likely correctly identified the AC input relay as the
most likely cause of the visible arcing when the generator is
turned off at the inverter?<br>
2. Should manual control be a permanent solution?<br>
3. Any other suggestions for this customer?<br>
<br>
Thank you,<br>
Allan<br>
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<p class="MsoNormal"><b>Allan <span class="SpellE">Sindelar</span></b><br>
<span style="font-size:10.0pt"><a
moz-do-not-send="true"
href="mailto:Allan@positiveenergysolar.com"><u><span
style="color:#000099">Allan@positiveenergysolar.com</span></u></a></span><br>
<span style="font-size:10.0pt">NABCEP Certified PV
Installation Professional<br>
NABCEP Certified Technical Sales Professional<br>
New Mexico EE98J Journeyman Electrician<br>
Founder, <b>Positive Energy, Inc.<o:p></o:p></b></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt">A
Certified B <span class="SpellE">Corporation<sup><span
style="font-size:7.5pt">TM</span></sup></span><br>
<st1:address w:st="on"><st1:street w:st="on">3209
Richards Lane</st1:street><br>
<st1:city w:st="on">Santa Fe</st1:city>, <st1:state
w:st="on">New Mexico</st1:state> <st1:postalcode
w:st="on">87507</st1:postalcode></st1:address><br>
<b>505 424-1112 office 780-2738 cell</b><br>
<a moz-do-not-send="true"
href="http://www.positiveenergysolar.com/"
target="_blank"><u>www.positiveenergysolar.com</u></a><o:p></o:p></span></p>
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