That got complicated…

Sorry. Life kind of came at me from all sides this week but I think I have a good grip on it now. Could be wrong.

Starting Friday, Ian’s electrical system went completely south. 3 out of four mornings found the inverter shut down with red error lights blazing away in a most accusatory manner. All signs seemed to point to the batteries – which came as no surprise because these batteries are more than 14 years old which is old – but the signs were confusing.

I am not an electrician, nor do I play one on television but I have been poking around with DC solar power for a long time now. Which is why the diagnosis came as kind of an embarrassment. My first thought was to test each cell individually…

…and so I dusted off my ancient digital hydrometer, gave it a new battery, and recorded specific gravity for each cell…

…and that seemed to indicate only one unambiguously bad cell. But that wouldn’t cause all this trouble by itself, I thought. I didn’t want to do anything rash until I had consulted an older, wiser head. I texted Neighbor S and requested a consult at his leisure.


…I got a prematurely empty propane bottle and a BIG whiff of gas at the Secret Lair’s bedroom regulator. This is becoming a common problem – a nearly-new hose suddenly decided to leak like the proverbial sieve.

That was yesterday, and it was cause for anxiety because suddenly I had the makings of a scheduling conflict. That very seldom happens anymore and it always raises my stress levels. I knew that Neighbor L planned to go to town yesterday but that it would be a long trip because she was going to get her hair done. This was not a trip I greatly desired to share – but I really needed a new hose and the alternative was to ride my bike. I’m still healing from a lot of painful joints at the moment and the bike was also not an attractive option.

I elected to tag along with L, worrying all the while that now I would miss my appointment with S which was scheduled for whenever he wanted to. Turns out I needn’t have worried…

I got my hose, L got her hair done, we went home, I fixed the propane leak and re-lit the bedroom heater, and almost on the next beat S texted his readiness to meet me at Ian’s place. So that worked out great.

S took a much simpler approach to diagnosis than I had – he just measured the resting voltage of each battery. By now it was late afternoon and all the batteries should have been fully charged with a reading well over six volts. Of the eight batteries, three were emphatically not doing that.

So rather than one bad cell in one battery I had three underperforming batteries. And that would most certainly cause the problem the system was having.

Okay fine – I now had a plan of action. It’s a 24-volt system which means it needs at least four 6-volt batteries. I had five. Re-wiring was in order, and I hit that early this morning. I confirmed the findings of the previous afternoon with my own voltmeter…

…tore the bank apart and removed the three dying batteries…

…and ran into another problem – this one inside my own head.

I have a sort of problem doing math in my head. Arithmetic is no problem but any math higher than that makes my eyes glaze over. I’m good with words but not with numbers, and for some reason this also extends into visualizing electrical circuits. Eight six-volt batteries can make 24 volts when connected series-parallel. FOUR six-volt batteries can not. I was rushing, because I was due at Neighbor L’s at 10, and I got flustered. Finally – wisely – I called a halt.

Neighbor L’s horses are scheduled to leave home forever on Friday. Yesterday she reminded me of my promise to come over and help her service their horse trailer, which had not moved in at least a couple of years.

Lube up the hitch and get it working, then hitch the trailer to their big pickup and get it moved away from its parking spot, turned around and backed up to the workshop. Fire up their big compressor, air up five tires and pack four sets of bearings. Took about an hour and half. Tobie stayed in the Jeep and was SUCH a good boy. Remember two years ago when I left him in D&L’s Jeep and he tried to eat their parking brake handle? Well, that was puppy Tobie. Adult Tobie is not prone to anxiety issues. He just wants to come along and enjoy the show.

Meanwhile I was able to clear my mind and apply it a bit more sanely to my circuitry puzzle. With four six-volt batteries, to make 24 volts you wire them in series, not series-parallel. A much simpler circuit indeed. So after saying goodbye to L I went straight back to Ian’s and did that.

And now his electrical system is working again, albeit with half the battery capacity. Which will hopefully tide us over while Ian decides what (if anything) he chooses to do about new batteries.

And now to email him the good news…

About Joel

You shouldn't ask these questions of a paranoid recluse, you know.
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9 Responses to That got complicated…

  1. matismf says:

    So what are you doing with the FIFTH good battery?
    What happens if you leave it just sit for a while?

  2. Joel says:

    Right now it’s parked inside the box. If one of the four active ones craps out I can swap them. It will (probably) hold a charge for a good long time, I’ll keep an eye on it.

  3. Anonymous says:

    I thought that Ian’s whole pre-Forgotten Weapons history was that he was a 12v system gearhead. Isn’t he better equipped to determine the problem?

  4. Anonymous says:

    14 years is a LONG time for lead-acid batteries, even when they are cared for. Well done sir.

    That said, Ian may need to consider all 8 in his budget.

  5. John says:

    I would also suggest against mixing new batteries with older ones in a battery bank, especially with ones 14 years old!

    My expectation is that at times when not being charged, the old (weaker) batteries will tend to draw current from the new batteries, shortening the life of the new batteries.

    Interested to see how you get along on the four batteries. Hoping for the best 🙂.

  6. Joel says:

    Actually right now it’s not going well. The four batteries should be able to run the system with the minimal load that’s on it, but the system won’t stay running. I don’t know why, but I’m working on it.

  7. John says:

    I’m going to guess that when there is good sun on the panels (the panels are doing the work) the system works with that minimal load? But, no sun and the system soon shuts down?

    If so, seems the system is working properly but the batteries have only a small fraction of their rated (new) capacity. Classic behavior of old batteries. 😕

    There are no dead cells which is good, but a voltage check can only tell approximately how fully charge the batteries are, NOT their capacity (Amp-Hrs). For that a load tester is helpful. Not need here seems, as looks like batteries can’t long support even a minimal load!

    I’m thinking the demands on the batteries is usually pretty low (Ian not there) so the falling bank capacity went unnoticed. At the Lair you’d notice way sooner that your system had a little less umph!

    All the batteries being same age and in the same connected battery bank, it’s reasonable to expect that they are very nearly all in the same condition. If one is a little weaker its voltage will be a lower than the others and current will flow continuously between them until all are the same. Thus weaker batteries will tend to draw down stronger ones. (A significant issue if dead cells present). Had one or two of the removed batteries had a dead cell maybe cutting the bank size in half would have bought some time.

    Hitting it with the Honda and the charger you can help the panels max charge the 4 (or 8 ! ) battery bank for a bit of life extension? – probably a pain in the ass though!

    Fourteen years is a pretty good run!
    Good Luck!

    (Cost of lithium batteries has come down. Not sure if enough to make sense to Ian though.)

  8. John says:

    Crap – 24 volt system, 12 volt charger – doable but more complicated!

    PLAN B:
    Pick two (or four) of the removed batteries and put them on the honda and charger at the lair and try to do an “equalizing” charge! See if you can up the specific gravity of the weaker cells!

    Believe your charger will supply ~14.8v for ~15min then drop to float volts. But disconnect it for ~ one minute and it resets.

  9. malatrope says:

    Those poor batteries were ready for the trash four years ago. That they valiantly made it this far is a testament to your excellent maintenance. You have to make the case to Ian that he must have a new battery bank. Since he’s rich now, a famous published author, he should be able to afford lithium iron phosphate. The only thing you have to do to them is top-balance them occasionally if they are in series. Or buy a single battery unit of the voltage you need, which will balance the cells on its own.

    I’ve had very good luck with this brand. Here’s what you need in one simple package. Just parallel them if you need more capacity than 200ah.

To the stake with the heretic!