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Comment by phreenet | Hacker News Reader

Powering a house for days is a very broad statement. Does this include things are that electrified such as a central air conditioner and/or heat pump? Electric water heater? Electric clothes dryer? Maybe the last two would be considered a luxury in an emergency situation but I've lost power for 3+ days twice in the past two years during a major snow/ice storm. It's brutal not having a heat source and if you live in a hot climate I'm sure it's equally brutal in the summer.

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The assumption is apparently[0] 30 kWh/day counting as "full usage," giving 3 days of runtime. Rationing that can give you up to 10 days, implying 9 kWh/day.

I have a full electric house in central Texas, and my daily usage in the summer is around 2000 kWh, so I could get about 1.5 days of power if I did nothing to ration it. If you have a gas water heater, stove, dryer, etc. it'll obviously stretch out.

[0] https://www.thedrive.com/tech/40695/the-electric-ford-f-150-...

EDIT: s/daily/monthly

What are you using (and how large is your house) that draws 2000kWh a day? This is an amazing amount of power draw. The average monthly draw for a house is under 1000kWh.

Just guessing, but based on context, I think they meant their daily usage results in 2000kWh per month.

Correct, added an edit.

2000kWh a day? Our apartment houses family of 4 and we spend 2400 kWh a year (incl. electric stove)

The extended range version has a 131 kWh battery, the average American household uses ~900 kWh per month. So yes, it could power your heating or cooling for days in addition to everything else. A big home central air system will pull 5 kW and won’t run 100% of the time.

kWh is power over time. When planning a power backup solution you have to account for spike loads, building code inspectors will insist on it. For an average central air conditioning system the outdoor refrigerant compressor has a locked rotor starting amp requirement of ~80A (typically). According to Ford the max amp feed back to your home from the truck is 80A. Building code will let you hook up your outdoor unit only in that case, the inside air handler will not be allowed because (assuming internal is 15A) you would be asking for 95A. You will most likely require either load shed devices or a transfer switch which will most likely not include your whole home or your AC/HeatPump. At least by building code.

In America anyway, you size based on FLA, not LRA. NEC Article 430[0].

My heat pump's compressor has a nameplate LRA of 134 A, and a FLA of 26.4 A. The breaker is 50 A.

[0] https://www.ecmag.com/section/codes-standards/motors-motor-c...

I don't believe electrical codes have anything to say at all about the sizing of emergency generators.

That's a good point. It really depends on usage, though it's not unfair to just use the average when writing an article. And by that standard, 'a few days' is probably fair.

During the winter, that kind of battery capacity could power us for a couple weeks. Everything other than the furnace blower is natural gas. During the summer, ... well, fortunately we don't need air conditioning here to survive (one-off 117F events notwithstanding).

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