Back up Generators for houses?

All good answers, except it can be done for $5000. Quality deep cycle batteries cost about $150 each, and can supply over 1000 watts briefly. 20 at 6 volts each will power a 20 kw peak rated inverter, so they can run your central heat pump or your clothes dryer. For the clothes dryer start it on air only and switch quickly to heat. That will reduce the starting surge. You probably can not run both at once, so you need to time share, but with either running you can turn on a bunch of other stuff, but not more than one more heating or cooling device. If the utility is back on in a few minutes, you can stop running down your batteries and start recharging them. For more reserve watts and more watt hours, you need to think 3 or 4 fork lift batteries = expensive and about 1/4 ton each. Possibly Tesla motors will sell you a replacement battery for the Tesla roadster for about $25,000. That will out perform 4 fork lift batteries = 50,000 watt hours, but it weighs almost 1000 pounds. Neil

Generators run on gasoline or diesel. There just isn't enough energy in a lead acid battery to run a house. You would need a bank of batteries and an inverter to convert the DC to AC,and some way to recharge the batteries. The cost would be prohibitive. Most backup generators run on gasoline and will power some of the appliances in a house. Don't expect to use an electric dryer, stove, washing machine or dishwasher. You might be able to run a TV, refrigerator, lights, a computer, and a radio.

No, there are none that run on battery. The most reliable are those that run off of natural gas and are hooked up to the cities natural gas line. When the power goes out on your house, these have a relay that automatically starts them and puts them on line without your help, within 30 seconds of losing power.

There is not enough energy in a typical battery to power a house. A typical AA battery can have up to 2.60 Wh (watt-hours) of energy, not even enough for a regular light bulb for more than a few minutes. A light bulb can be either 40 or 60 watts, meaning in one hour using 40 or 60 Wh. You would need several to power a single regular light bulb for an hour, you would need a LOT for an entire house.

For the kind of load and running time you'd need for a house back-up system,

the batteries would cost more than the house.

There are fueled residential sized engine/generators that will run on your

natural gas or propane supply rather than gasoline though.

Batteries are good to provide backup power to your computer for an hour or two, but for the whole house you need a gas powered generator.

Batteries hold too little energy.

your 30 L tank holds about 1000 MJ or 300 kW-hours

A large auto battery holds about 1 kW-hour

So you would need 300 batteries to hold the same energy.

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The short answer for a whole house is NO.

A single lightbulb maybe but throw in a fridge and you're done

if there is another source of electricity company will close