Off-grid power management on a frigid morning…

Okay, so it was definitely going to get cold last night. It’s been overcast the past two days, snowed on and off and never got above freezing all yesterday, and overnight the sky cleared. We’re at 6000 feet: it’s gonna get cold.

And it did, too, without setting any records…

But what I was most concerned about was the batteries, which at twilight yesterday were doing this…

That’s not good at all. It’s time for emergency power conservation mode. I went out to the powershed and shut the inverter right off.

When I first wired the cabin in 2010 I had no 12-volt lighting or appliances at all. I’m sure such things existed but I only knew about them in an automotive context and auto 12-volt lighting works great in the cabin of a car or truck and nowhere else. That meant that if my inverter wasn’t on, nothing was on. Time to break out the kerosene lamps and/or just go to bed.

Things started changing a lot in winter 2014 when Big Brother sent me a kit with some rudimentary 12-volt household lighting. That worked really well, and the concept was proven in summer 2015 when a lightning strike fried my scrounged RV inverter. I couldn’t charge a cellphone, but I still had lights. So in 2017 when I built the bedroom addition, all the lighting was 12-volt and so was the ceiling fan. At the same time, LED bulbs with standard connections became affordable, and that was a whole separate revolution in power management for a penniless hermit with a (very) small off-grid system.

The reason this matters is that sometimes in winter my power situation can get low enough that usually insignificant power drains, like the parasitic draw from the inverter, become a no longer acceptable issue.

I hadn’t gone a night without the inverter for quite a while, and I was kind of curious to see how it was going to trip me up. I tried to make a cup of tea and was forcibly reminded that my new stove…

…couldn’t light a fire without wall current, but that was no thing. I’ve got five different ways to start a fire in the main cabin alone. I didn’t hit any serious snags till this morning while trying to compose this very post. But in the morning I did get a mild surprise…

The indicated voltage, with the batteries completely at rest, was even higher than it had been last night. These batteries are only about 2 and a half years old, but it’s still nice to know they’re in good operating condition. 🙂

My laptop’s battery was fully charged, and my internet connection is through my iPhone, so I anticipated no problem posting this entry without recourse to the inverter. But I forgot something very important…

I’m down in a desert hollow, a long way away from and not in line of sight with any cellphone tower, which means that without artificial assistance my internet connection is, well, problematic. Suddenly trying to upload large blocks of data might work, or it might do what it did this morning. Text, maybe. Photos, no. Not only no. Hell no.

Two years ago Big Brother sent me my signal booster, and things changed abruptly – changed so much that I’ve gotten spoiled. Casually thought I was going to just load a bunch of jpegs without any trouble at all. Ha! So I got my pants pulled down before the coffee kicked in. And then I went out in the cold and turned the inverter back on.

Happily there’s not a cloud in the sky at the moment, so I expect the problem to start correcting itself as soon as the ice melts off the solar panels.

About Joel

You shouldn't ask these questions of a paranoid recluse, you know.
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16 Responses to Off-grid power management on a frigid morning…

  1. Stefan v. says:

    If you’re adventurous you could find the internal power requirements of the booster and rig a DC supply from your batteries and bypass the internal AC/DC converter, probably a switching type. The circuit board likely has 5V, so it could be as easy as getting a 12V car cig lighter/USB converter and some wires and doing some easy soldering. What specs are in the user manual?

  2. Joel says:

    If I’m turning off the inverter, chances are I don’t really care what all’s happening on the internet for the rest of the evening. 🙂

  3. Robert says:

    I’m still flabbergasted that your GAS stove needs electricity to make flames. My mother’s gas stove uses an electric igniter, but without electricity it will ignite just fine with a match.

  4. jed says:

    If you look up that Weboost thingy, you’ll see that the power comes from a 5VDC wall wart. Hard to read the image, but I used a screen magnifier, and I think that’s it. Joel could, if he felt so inclined, post the spec from the plug side of that thing, just to confirm, and also include the amperage. A 5VDC from nominal 12VDC supply should be a simple thing to find, and it likely just needs a typical 2.1mm (inside) barrel connector on the end, wired with the correct polarity. If the amperage needed isn’t too high, there are USB power from 12VDC converters, and then it’s a matter of a USB to barrel-plug cable. Actually, the new USB power specs are pretty beefy.

  5. Klaus says:

    I’m curious like Robert above what exactly is it about that particular stove that the burners can’t be lit with a match when the power is out?

  6. B says:

    The burners on top can be lit, it is the oven that needs 120VAC to operate. Gas valve and igniter.

  7. Joel says:

    Robert, I was unclear. It’s only the igniters that require wall current, the gas valves are just gas valves. The stovetop spews gas just fine but I needed a more low tech way to ignite it.

  8. Robert says:

    Joel@839: Ah. Thank you. I is unconfused now on that aspect. However…
    B: My mom’s gas oven has a pilot light and no need of ac to operate. Needing 120vac to operate a gas valve is… possibly more complex than needed..

  9. Robert says:

    “a more low tech way to ignite it.” A flint striker thingy would work well without the disadvantages of matches.

  10. Spud says:

    Or you could just dig the Honda out, and give it some exercise time. In fact it would probably be good to do once in awhile anyway.

  11. Mark Matis says:

    Electronic lighters will also ignite those burners even after those lighters run out of fuel! The piezo-electric sparky thing does not require any external electrical power to make the spark! I use an old empty one to light my barbecue grill regularly.

    By the way, did the rest of the stump socks show up?

  12. Joel says:

    Mark, the next visit is due in a week.

  13. B says:

    Robert: Your mom’s stove is obviously old. Stoves made in the past 20 or 30 years use a gas operated valve and an igniter to start the gas flame in the oven. I too like the older pilot light and mechanical gas valve systems, but the industry has moved away from that. Evne gettingparts for such older units is getting difficult.

  14. jeff says:

    Hey Joel, apologize if you already discussed the possibility though have you considered getting an old electric car EV and using the battery pack? Supposedly they have a lot of life left though not enough to run a car. Europe and Japan have done some work about repurposing ex EV batteries. NREL spent some money writing about it. Not sure what came of any of it.

  15. Joel says:

    jeff, there is an increasing number of videos from people who are working on that very thing. Battery trays from defunct EVs may come to be a great source of power for off-grid homesteads in the near future. Everything I’ve seen about it so far, though, suggests that, quote, “it’s not that easy.” There are compatibility issues with existing charge controllers and inverters.

  16. You have to do some extensive repurposing with EV battery packs. I know that a Toyota Camry Hybrid’s battery is 260v at some hellish amount of amps. It would have to be broken down into it’s component “sub-batteries” and those rejiggered into a group(s) of batteries that are 12, 24 or 48 volts, or at least very close to those numbers. Anything higher drives the expense up to the point that it’s as cheap to buy new LiFePo batteries.

    A friend of mine had this notion that old fork lift batteries might be a possible solution. I don’t know enough about those to opine on the subject.

To the stake with the heretic!