can i use a deep cycle marine battery in my blazer? i donnt really understand how the deep cycle batries work. right now somethimes when i have my brights on and i try to roll up the windows there is a major shortage on battery juce. everything starts dimming and brightens as the alternator turns over. i have to shut off the lights in order to put the windows up. the alternator seems new too, its much shinier thatn the rest of the engine bay.