[Lazy Iguana]

A car battery is not going to work very well or for very long.

To understand why, you need to know about this simple formula.

Watts = volts x amps. This means amps = watts / volts, or volts = watts/amps.

Sp lets say you have a 100 watt heater that uses 120 volts. The draw is only .83 amps.

But what if you want that same power using a 12 volt battery? Lets find out! The load on your 12v battery will be 8.3 amps to produce the same 100 watts the heater needs. That means 10 times more current (amps) is needed to produce the same power (watts) at 12 volts VS 120 volts.

You can think of volts as buckets, amps as the number of buckets, and watts as a tub. Do you need to make more trips to fill that tub if you use a large bucket or a small bucket? 120 volts is a bucket 10 times larger than a 12 volt bucket.

In other words, you will need a very large battery bank and a very large power inverter.

Lets say you want to back up a total of 1000 watts of stuff (heaters, pumps, etc).

1000 = 120 x amps. So if you have a generator you will need only 8.3 amps of power - or a very small gas generator.

If you go with 12v batteries, you need enough batteries to handle a load of 83.3 amps (1000 watts = 12volts x 83.3 amps).

83 amps is a heavy load for a battery. A standard auto battery will be drained rather fast. You will need multiple batteries connected in parallel (positive to positive, negative to negative). And even then, unless the bank is very large (and very heavy) you will quickly run out of power. For a load of 80 amps, you need marine house batteries normally used in cruiser sailboats or cabin cruisers without a generator. Anything with the word "marine" attached to it is expensive.

Oh yea, and for a constant load of 1000 watts you should get a power inverter rated for at least 2,000 watts, because appliances require more power to start up than to run. A 1,000 watt inverter can really only handle 800 watts continuous (more or less).

Now if your needs are simple, you can design a back up using only a battery and an inverter. Lets say you want to have only a 100 watt heater and a power head that consumes lets just say 10 watts. For this a somewhat inexpensive 300 watt inverter would work. Applying the formula we can see the load on the battery is only 9.16 amps. Not too bad - and that heater is only on for brief periods of time so the constant load will only be less than 1 amp.

Now what you can do is hook the inverter up to the battery, plug in the heater and emergency power circulation pump, then connect a battery maintainer to the battery that supplies a constant charge of 12v at 1.5 amps. Set the heater to kick on at a temperature below what you main heater kicks on at. The pump will just run all the time.

If the power quits, everything goes black. The battery however is 100% charged because the charger is supplying all the power the circulation pump needs and still has enough to keep the battery up. So your circulation pump is still on. When the temperature drops - the emergency heater kicks on.

Hopefully, the main power returns before the battery runs out.

Your best bet is to get one of those Honda EU generators. There are three models, the EU1000i, the EU2000i and the EU3000i. I have the EU2000i. It produces 2000 watts at 120 volts - or about 15 amps Same as a standard wall socket. So whatever I can plug into one wall socket without blowing a house fuse I can plug into the generator. It is very quiet - running at 100% it is still quiet. Put it 100 feet away outdoors and you will barely (if at all) hear it. And it only weighs about 40 or 50 pounds, so it is portable.

The EU1000 produces 1000 watts, the EU2000 produces 2000 watts, the EU3000 produces 3000 watts. You can hook two EU2000 together to produce 4000 watts total power.

The i stands for "inverter". The power these generators produce is very clean. The generator creates 12v power and then inverts it to 120v true sine wave power. So it is safe for electronics.

There is a modification for the EU series generators to allow them to run off an external 5 gallon gas tank. The internal tank for the EU2000 is only 1 gallon or so. For extended running, the external tank means less refilling.

A battery backup system like the simple one pump one heater thing listed above will work for times you are at work when the power quits. When you get home, you can crank up the generator.

Generators require regular maintenance. U keep my generator gas tank full (prevents moisture from getting in) and I use Sta-Bil in the gas (same stuff I use in the boat). I also fire the generator up once a month or so and let it run with a hair drier plugged into it for a few minutes - just to keep it all lubricated and to prevent the fuel from going bad and gumming the thing up. At least once a year, or whenever the manual suggests (based on hours of running time) you should change the motor oil in the generator. I change my oil once a year (start of hurricane season so I do not forget) if I do not use it enough in a year to hit the 100 hours (or so, I forgot) that Honda suggests between oil changes.