Well, I had wondered.

Ever since the electrical system rebuild, my inverter has shut itself down due to low voltage exactly twice – before this morning. Both times were due to profligate behavior on my part following cloudy weather. But the past four days have been gloriously sunny. So if I left my ‘pooter on all afternoon and into the evening until around nine, I saw nothing wrong with that. A few months ago there’d have been nothing wrong with that. The batteries were fully charged yesterday afternoon – as fully charged as they can be, poor things.

And everything would probably still have been all right if I hadn’t fallen asleep in my chair, book in hand, CFL lamp burning, and woke up with a stiff neck after midnight. Even that wouldn’t have caused a problem a few months ago – but that’s not now, and then I compounded the error by switching all my gear on this morning before the sun rose over the top of the ridge, and that was the final straw. The inverter clicked off, and we were done.

The really distressing part was how quickly after sunrise the battery voltage read over 13 volts. It’s a shallow vessel that fills quickly…

But now at least I have a better idea of what my batteries can do in their weakened state. The good news is that we’re past the solstice, so the days will be getting longer from now on. And I already know not to be stupid when it’s cloudy. As long as I don’t overuse the ‘pooter I’m fine until I can replace the batteries, even though that will probably take a while. At least through the winter, every erg of fund-raising will go toward eye surgery even if I read by kerosene lamp.

I’m going to shut it all down now and go do my chicken thing. Later than I should, but it’s still frickin’ cold.

About Joel

You shouldn't ask these questions of a paranoid recluse, you know.
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5 Responses to Tilt

  1. Michael Gilson says:

    I’ve never done this myself. It was told to me by a college instructor who had done it when he was young, and he emphasized how dangerous it was. He had restored a lead acid battery for a VW Beetle by draining the acid, letting it dry, melting the tar holding the top on the body with a torch then removing the top and plates. Then he cleaned the sludge out of the bottom, replaced the top and plates then remelted the tar to seal it again and refilled with fresh acid. He explained that the rising sludge had been shorting out the bottoms of the plates and once it was removed the battery regained a large part of its capacity. He also pointed out all the ways he had risked death doing it (acid burns, steam burns, tar burns, fire and lead poisoning just to name a few) just to save a few bucks. Plus I don’t even know if lead acid batteries are constructed the same way anymore. But the limited information is yours to do with as you see fit.

  2. Roberta X says:

    There may be better ways, Michael.

    Joel: consider adding a mechanical shut-off timer to your want list. It’s a pretty common item, replaces a standard light switch. You could even wire it into an extension cord. Plug the reading lamp into it and set for however long it usually takes you to nod off, plus a few minutes.

  3. Roberta X says:

    …Yikes. Desulphating a lead-acid cell is not for the faint of heart. Srsly not. Worse than I remembered. But you can find info on the web, and you don’t have to take the thing apart.

  4. Joel says:

    Yeah, I do confess I’ve never heard of anybody taking a battery apart to desulfate it. And that wouldn’t actually desulfate the battery anyway: If sludge is forming at the bottom, it must be caused by the plates delaminating or by really severe sulfation. Either way, the plates are toast. Also, that’s scary.

    But in the olden days we actually did have to mix our own battery acid in the shop. Batteries were shipped dry, and came with sealed bags of damn-near-pure sulfuric acid. That was some scary shit. The practice was ending at just about the time I became a professional mechanic, but it wasn’t unknown. “Pour the acid into the water, not the water into the acid.”

  5. Expat says:

    I had the same problem. As you say, they charge almost at once and discharge the same way. Brought the 4 GC batteries back to Cosco for refund and came back with 8 more. The loses from solar system inefficiencies including panels, charge controller, battery bank and inverter really add up.
    The trick in winter seems to be to shut the inverter off when not in use. That and never allow the batteries to get below 50% discharge. That’s hard to judge during the day as the panels put a false voltage reading onto batteries.

To the stake with the heretic!