I have this tractor fog light that I want to use on my bike but I'm having trouble converting it to battery operated. I'm pretty sure it's a 12volt sealed bulb. when I hooked up a 9volt battery it wasn't bright enough, so I hooked up two, then three 9volt batteries but every time it would shine bright for about two minutes then die like it drained the batteries. What am I doing wrong?am I going to need a car battery to get this bulb to stay lit?