Do you know the ohms resistance of the atomizer? (you unscrew it from the base and there's a number like 1.5 or 2.0 on it.)
Typically to get good vapor, your voltage input from the battery has to be at least 2 numbers higher than the amount of ohms on your atomizer. E.g. if the atty is 1.5 ohms you should be vaping at 3.5-3.8 volts, (4 is pushing it). If your atty is 2 ohms you should use anywhere between 4 and 4.4 volts.