[rootusrootus]

Yeah we did a similar thing. Same situation, spouse and I both work from home, and we got hit by a multiple day power outage due to a rare severe ice storm. So now I have an EV and a transfer switch so I can go for a week without power, and I have a Starlink upstream connection in standby mode that can be activated in minutes.

Of course that means we’ll not have another ice storm in my lifetime. My neighbors should thank me.

[VTimofeenko]

We had a 5 day outage last year, got a generator at the tail end of the windy season and made exact same jokes.

A year later another atmospheric river hit and we had a 4 hour outage. No more jokes.

Make sure to run that generator once every few months with some load to keep it happy.

[rootusrootus]

Well, it's an EV with a big inverter, not a generator, but I get your point. And I do periodically fire it up and run the house on it for a little while, just to exercise the connection and maintain my familiarity with it in case I need to use it late at night in the dark with an ice storm breaking all the trees around us.

[VTimofeenko]

Oh, I see! Genuinely curious -- what kind of EV has a battery to power a house for a week?

> maintain my familiarity with it in case I need to use it late at night in the dark with an ice storm breaking all the trees around us.

That's the way to do it. I usually did my trial runs during the day with light readily available but underestimated how much I needed to see what I am doing. Now there's a grounding plug and a flashlight in the "oh shit kit".

[Nextgrid]

> what kind of EV has a battery to power a house for a week?

Assuming their heating, cooking and hot water is gas, a house doesn't actually consume that much. With a 50kWh battery you can draw just under 300W continuously for a week. I'd expect the average house to draw ~200W with lighting and a few electronics, with a lean towards the evenings for the lighting.

[VTimofeenko]

On paper the numbers look right, but a week off _50kWh_ EV battery feels off.

What follows is back of the napkin calculations, so please treat it as such and correct me if I am wrong.

1. Inverters are not 100% efficient. Let's assume 90%

2. Let's also assume that the user does not want to draw battery to 0 to not become stranded or have to do the "Honda generator in the trunk" trick. Extra 10%?

3. 300W continuous sounds a bit low even with gas appliances. Things like the fridge and furnace blower have spiky loads that push the daily average. Let's add 100W to the average load? I might be being too generous here, but I used 300W, not the 200W lower bound.

4. Vehicle side might need some consumption. If powering off the battery, it would probably need to cool the battery or keep some smarts on to make sure it does not drain or overheat? Genuinely not sure how to estimate this, let's neglect it for now.

Math is (50kw - 10%(inverter loss) - 10%(reserve)) / 0.4 = 100 (hours), ~ 4 days.

The above calculations assume a sane configuration (proper bidirectional wire, not suicide cord into 12v outlet). Quick skim of search for cars with bidirectional charging support for home shows batteries between ~40kWh(Leaf) to 250 kWh (Hummer).

So looks like one should be looking for ~80kWh battery, which actually most of the cars in the list have.

Again, very back of the napkin, would probably wanna add 20% margin of error.

[Nextgrid]

Actually yes one thing I didn't consider in my calculation is the fridge (mostly because it's a spiky load that rarely comes on and I based it off my own apartment's instantaneous consumption at the time which was ~100W since the fridge compressor wasn't running).

Indeed with the fridge it pushes it a bit. But to address some of your other points:

> it would probably need to cool the battery

I'd expect if you're in a storm then you probably don't need any cooling - not to mention a 300W load is nothing for an EV battery compared to actually moving the vehicle. I'd expect some computers in the vehicle to be alive but that should be a ~10-20W draw.

On the other hand, my calculation assumes ~300W continuous. I expect the consumption to lean into the evenings due to the extra lighting, and drop off during other times.

But yes 80kWh might very well be what the OP has; I intentionally picked 50kWh as the lowest option I found on a "<major ev brand> battery kwh" search.

[mlrtime]

I just asked my wife the other day: "Does it feel like we're having less power outages now that we got the generator?" :)

[kiddico]

Thanks for taking one for the team.

[mlrtime]

Same! Texas?