Subject: A mystery to me..... [RE-wrenches]

[Steve Willey, Backwoods Solar]

One clue might be that battery voltage dropping from 54 to 27 sounds
unusual.
I have seen circuits with unusual unexpected surges, like a freezer that
draws far more than the usual surge if the breaker is switched off and back
on while it is running, because compression pre-load has no time to bleed
off before the re-start.  In my own home I was confounded on what load could
possibly do that when doing a like test and hit the freezer circuit. I would
go see what, besides the known pump, is on the other breaker with the surge
problem.

Still, battery dipping that far down in voltage will certainly shut off the
inverter.  I would check to see exactly what cells or cables are allowing
that much drop (unless the battery is really undersized).  A couple of
normal surge loads that the generator or inverter can handle, coupled with a
high resistance battery cable or cell might explain why no inverter you
tried could handle it and the generator could.

Steve Willey,
Backwoods Solar Electric Systems
steve at backwoodssolar.com
Date: Sat, 18 Oct 2003 17:19:28 -0400
From: penobscotsolar at midmaine.com
Subject: A mystery to me.....



Hello all,
   I'm having no success in troubleshooting a system we installed almost two
years ago that is three hours travel time each way. It has operated
flawlessly since installation. We have had no lightning in the area for
months.
   The system is an SW4048-PP with 24 Surrette KS-25 batteries. It was
originally set up for generator only use (against my recommendations) but
they quickly added a 1.2 KW array within the year. We aded an Outback MX-60
to the system this last July.
   I arrived at the site with replacement inverter in hand. We started up
the original inverter with manual bypass breakers both off. It ran fine,
starting up and going into search after 20 seconds or so. Setting it to ON,
again, it ran fine. We turned off the main in the house and threw the
inverter breaker in the bypass and it continued to run fine. We turned off
all the breakers in the main panel and turned the main on and it ran fine.
We threw the first breaker and it continued to run fine. We turned off the
first breaker and continued in this manner until we threw a breaker (
labeled track lighting) and I saw the battery voltage suddenly drop from
54.4 volts to 27.2. The inverter shut down with no error reading and without
any breaker tripping anywhere. We shut off this breaker and turned the
inverter back on. It ran fine.
    We continued on and found 2 breakers which powered sub-panels both had
the same effect. One sub powered a Grundfos 1/3 hp SQ-O series 110 VAC
submersible, among other things (mostly lights in the room where the sub
panel is). It seemed as though certain loads were dragging the inverter
down.
    To shorten this story, we replaced the inverter and voila! the same
problem!!!!!
    When they power the house with the generator through the manual bypass
switch everything runs fine. The system has separate structure ground (for
the array) and system ground (the electrical systems ground)
     WHAT AM I MISSING???
Daryl
Penobscot Solar Design

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