Model Rocket Engines

I just got back into model rocketry. My current goal is to shoot a rocket to a mile high. My only problem is that the igniters need 12 volts and 3 amps to start these composite motors. I don't have an extra car battery lying around for this purpose. Does anyone have a suggestion on how I can get that kind of current/voltage to the igniter?

Just take your car to the launch site, and hook up cables to the battery. Have long enough cables that you are able to launch some distance from your car, though.