What I have: A 300 watt clamp light.

What I need: A cheap way to power the light on piers around the Seattle area.

I'm trying to fish for the squid the proper way, which means using a light to penetrate the surface of the water and attract more of those little guys. The issue is this; I've been having problems finding information on how to power a clamp light with a regular two prong ac chord. I see people with batteries but you obviously can't just hook an ac chord up to the +- inputs on the car/marine battery. A power inverter would work but apparently it would drain the battery in under 2 hours (not nearly enough time to catch a lot of squid).

Any information on night fishing lighting for relatively cheap would be greatly appreciated. I'm looking for something cheap and effective, piers are bright but generally not bright enough to really attract the schools.

Thanks,
Colin