A battery is a good mod if you have an upgraded stator and high watt lights.
You won't have any dimming and you could just run the lights without the motor which could be cool at night or just to have parking lights.
You could wire in remote control lights, an alarm, lots of possibilities.
I you want to run leds (correctly) a battery is required.
there is a good write up from a member named phragle that has the process to add a battery to your blaster, I have been thinking about doing this in the future, but money and time has prevented me from doing this so far.