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by sah88 4136 days ago
~30kwh is the national average for daily use. 120 is crazy high unless your blasting an AC or heat all day. At 12 cents a kilowatt hour that's a $438 monthly bill.

Even 30 is pretty damn high. For someone living off grid with a purpose built/renovated structure ~5kwh a day gives you quite a lot to work with.
1 comments
IgorPartola 4136 days ago
True, but you want to be able to handle peak usage too. When 2 kW well pump kicks in, I don't want the lights to dim. AC is 3-5 kW and more to start, and so on.

Yeah, if your goal is to live off the grid to save the planet, that's a different story. Then the only question is how much will your Lithium based battery (mining, manufacturing, transport, recycling) affect the planet vs buying wind power from your local utility. If you want to do a little good and save a little money, putting batteries in your house is not the right thing to do. If you want to be independent of the grid in case of emergencies get a wood stove and a gas (or better diesel) generator. All around, I don't see where whole house battery backup fits into any scenario. I see data centers using these batteries, not residences.

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jacquesm 4136 days ago
I did the shorting current calculation on that battery in the pic elsewhere in this thread. The fuse was there for decorative purposes only, at those currents everything is a fuse, the one Ththing you really have to hope for is that it will douse fast enough and that there will be no air/fuel or H2/O2 mixture nearby. That's the main reason I built this pack into a little building (underground bunker really) of its own near the house but not so near that it would be a problem if it would break down.

The inverters were housed in the second half of that bunker so as far as the house was concerned nothing changed.

The whole system was capable of producing 11KW, two tandem 5.5KW inverters ganged to produce 240 V for well pumps and other large consumers (welder, plasmacutter).

It worked super good but you really had to keep an eye on the charge level when running big tools, the plasmacutter would drain the battery in about an hour.

But running the plasmacutter was the exception, not the rule so most of the time it was just powering a very low level of loads compared to most houses.

I really miss the system, and the farm it sat on.

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sliverstorm 4136 days ago
That's the beauty of lead-acid- it has one of the best (if not THE best) surge currents.

For example, the ~70Ah battery in my truck has a cold cranking amps rating of 700A, or 8.4kW out of just one battery.

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