Landlady gets a new battery bank

Okay, today’s the day. No more putting it off, Joel. Go get’em.

Somewhere in the desert is a prefab shed with a bunch of six-volt batteries. Those batteries are now Landlady’s property, which means they’re in the wrong place.

Since there are lots of these batteries, I’m going to haul only eight at a time.

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The simplest way to get these first eight out from underfoot is to put them where they belong.

They’re going to replace these eight big heartbreakingly expensive (and backbreakingly heavy) Rolls Surrettes which have reached the end of their lives.

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The first symptom I saw that something was wrong with these, was that they were literally boiling over. The electrolyte is supposed to boil slightly as it charges, but these were boiling so enthusiastically they were spilling battery acid on the floor. The second thing I saw was that the charge controller never went into Float, which meant it seemed to think the batteries were never fully charging.

A little quick work with a voltmeter confirmed that the controller was right about that. Most of these batteries can no longer get to six volts much less hold the level. So they have to go.

Rolls Surrette batteries are very expensive, and Landlady currently only uses her desert house a couple of weekends a month. That might go on for the lifetime of yet another battery bank, so the desirability of a less expensive alternative was being discussed just when an opportunity to buy some lightly-used smaller batteries fell open. Hence, today Uncle Joel schleps batteries.

My first attempt at quick-and-dirty schlepping resulted in something I’d have been embarrassed to explain to Landlady…

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The positive cable going to the inverter was too short for these batteries, and I actually got this far in my improvised solution before I gave it up as too redneck even for me.

So I pulled the whole thing apart again, and we drove to Ian’s cave where there’s a pile of concrete blocks. Then I came back and did it more righter than the first time…

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And now everything is turned back on, and everything works! Yay me. Unlike the Lair’s system, Landlady’s system works on 48 volts so it needs a minimum of eight batteries. That’s the biggest battery bank I ever personally cabled together. Thanks to Neighbor S, the Official Solar Power Technician of Joel’s Gulch, there are now big switches that shut off the input and output and reduce undesired arky-sparky to a minimum of zero. That makes the batteries much less uncomfortable to work with.

It’s entirely possible to cable all Landlady’s new batteries together in a humongously big serial-parallel circuit, and Neighbor S is welcome to do that at some later time if Landlady so desires. I’m not sure how we’d rack them all, but it could be done. But this bank right here is within my comfort level, so this is where I’m leaving it. I’ll go get the rest of them later, because my back is really singing to me at the moment.

About Joel

You shouldn't ask these questions of a paranoid recluse, you know.
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5 Responses to Landlady gets a new battery bank

  1. Malatrope says:

    When you do series-parallel, try to make sure the ages of each string match the other. Alternate newer-older-newer-older-newer-older-newer-older for each string if that’s how the batteries play. Otherwise, your strings will fight each other in discharge, charge, and quietude.

    If you do two strings, one newer-newer-newer-newer-newer-newer-newer-newer, and one with the older ones, the voltages of the strings won’t match and the older one will discharge the newer one. At least, without blocking diodes and other weird shit that isn’t worth the trouble they can cause.

    If you have enough short little cables, of course. FWIW, my Rolls-Surrettes are crapped out, though they still charge mostly to voltage, after ten years. But I measure their decrapitude by how many watt-hours I get out of one that’s charged as much as possible. At 400 amp-hours when new, they are down to about a tenth of that.

  2. Kentucky says:

    Joel, is there any “core charge” or otherwise “trade-in” associated with the Rolls Surrettes?

  3. Malatrope says:

    There wasn’t any “core” charge when I bought mine, from a battery dealer.

  4. Joel says:

    I really don’t know about core charges on those batteries. What they would be would be a factor in whether to sell them to a recycler or store them until the eventual day when she gets more like them, I suppose…

  5. Ben says:

    Just saying: I meekly suggest that you observe those batteries very carefully for a few days to double-ensure that your diagnosis is correct and that the problem isn’t the charge controller. Otherwise, you could wreck more batteries.

To the stake with the heretic!