p0rtia
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# Posted: 12 Jun 2011 19:50
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So I got back to my camp this spring and prepared to re-hook-up my solar, which involves, among other things, picking up my 6 6-volt golf-cart batteries from my tenant, who has kept them in his shed over the winter. Whatever amount of charging he did prior to May is neither here nor there. In May, it took him like a week apiece to charge four of the batts, while two would not charge at all. He relates that the charger indicator never moved at the 2 amp trickle charge, and, if he tried the 6 amp quick charge, he got an immediate fault alert.
I took the four batts that were presumably charged up to their summer home--a nice shed behind my 3 100 Watt 12 volt panels. I hooked them up in series parallel, and let nature take it's course. What happened was a series of alrams from my 1000 Watt inverter, alternating with "normal" voltage readings anywhere from 12.7 down to 12.2 (reading at night--during the day, the voltage stayed high). That inverter apparently then died completely (I have since tested it and it is fine, so I conclude that it actually shut down due to low voltage). I hooked up my back-up 1000 watt inverter, which alternated between "normal" readings and low batter alerts. I took the two batts that were oldest (and had taken the longest to charge) off the system, and with the two new batts, the system worked fine. I then set about getting a hydrometer, directed by our stalwart contributor, MtnDon. That took three weeks.
Anyway, the hydrometer is great and easy to use. As by this time I had concluded that my batter were sulfated (my word of the year), I expected to find a low specific gravity. Much to my delight, I discovered that the s.p. was fine (slightly higher than the 1.28 they're supposed to be, which I assume is off-set by the fact that the temperature was somewhat lower than it was supposed to be (around 70). But I'm assuming here. I am not sure how long to leave the hydrometer in the batt cell to get an accurate temperature reading.
As I had been charging the two problematic batts for a couple of days, I merrily hooked all four batts together again (they all had a full charge), and turned on the juice. All well until I went to turn off the inverter/shut down the system that night, and found a dreadful 11.6 volts registering on the inverter. Yikes!
I unplugged the system and check the specific gravity again. It was fine. Okay....
At this point I employed lateral thinking, and wondered if my cables and lugs were clean and getting top-notch contacts. Today I cleaned every lug, and the batt terminals, and hooked everything up again, and again everything looks fine. Can't wait to see what awaits me when I go up to turn off the inverter tonight.
Note that my panels and the battery shed and inverter are 100 feet from the cabin (the nearest source of anything close to southern exposure all-day sun). I have no idea if I'm bleeding electricity over this distance. I am at the maximum distance for the gauge wire I am using. I get a small voltage loss at the cabin, but use a regulator to boost it up to 120, and have never had a problem at the user end.
My questions are, aside from what the heck is going on, are--could there be a short somewhere? Some other flaw? If the s.p. is okay, are the batts okay? And if they're okay, why did they take so long to charge this spring? Should I use some sort of goo on the terminals to get a prime connection?
More after I check the system tonight. Actually, I only have the two older batts hooked up at the moment. If they pass muster, I'll try with the four batts again (after I get them all charged).
Running this home-made solar system has been an education. It took me four years to realize the importance of having enough panels to service the cabin, and to think of the batteries as an emergency back-up, rather something I can such dry every other day. I've learned enough to know that I am just getting started.
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p0rtia
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# Posted: 13 Jun 2011 08:38
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Thanks, guys. The thing is, both my mains charger (a Schumacher) and my solar charge controller, said that the batteries were charged. I understand that a solar charge controller is not going to provide a consistent amperage, but I don't think that counts as not "real" does it?
Yes, I've read about not mixing new and old batts, but I figured a lot of that had to do with the health of the batteries -- and the "old" ones are two years older, but lightly used. If that turns out to be the problem, I will consider it another less on learned--that's all I'm really doing here, trying to figure out how to maintain the batts in the long term.
BTW, when I went up last night, the batts were fine.
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