How do I convert an AC device to run on a battery pack? Answered

Not easily, if you're talking about "classic" incandescent bulbs. Those strings don't have a transformer; they use 110VAC directly from the wall.

If you are using LED light strings, you might be able to do it, depending on what kind of LEDs they are. If the light string has a transformer and rectifier built it (like a wall wart, but small) then you could cut that off and hook the bare leads to a battery holder. Make sure you get the ends oriented correctly (the whole point with diodes is that they only allow current in one direction). You'll need to know the voltage required by the LEDs in order to do this.

I'm pretty ignorant about the whole thing. I'm talking about the regular strings that you would buy like at family dollar or anywhere?

Hmmm....do the bulbs you have unscrew from the string? If so, they're incandescents, and you can't run an incandescent string off AAs -- you could use (several) lantern batteries, or connect a car cigarette-lighter plug to the wires.

If the bulbs are permanently attached to the wires, where you can't remove them at all, then they are LEDs.

They are regular little bulbs with the rectangler plug end with the 2 tiny wires. Little cheap regular Christmas tree lights.

Okay. Unfortunately those pobably aren't LEDs, they are incandescent. You'd need to use large, hefty batteries (like the square lantern batteries) to get any decent light out of them.

Shameless plugging! Only messing but still...

It would work, minus the van. Potable 120v outlet

Yeah but as goodhart says a deepcycle marine battery would do well but so does a 12V truck battery, they're usually in series for the 24v systems found on trucks, these are similar to heavy duty car batteries but have massive cranking current and larger capacities (not a huge difference in capacity). They withstand higher current draw from larger inverters much better than other batteries, granted they're harder to find now that most trucks are being fitted with single 24v batteries. Though you coulld run two twelve volt inverters in parallel and 12v each.

Wouldn't an even deeper cycle marine battery work better ?

Yes, its just that it doesn't have the plug for the inverter (but thats pretty easy to hook up by yourself)

Oh, I just meant that it would have more umph then a normal automobile battery.

Oh, and that's 8 non-rechargeable AAs, e.g., alkaline, carbon-zinc, zinc-air. Most rechargeable AAs (Ni-Cd, Ni-MH) have 1.2V cells, so you would need 10 to produce 12V.