What battery make and model do you have? The eGo class
batteries can be regulated 3.3 V, 3.7 V. I'm not sure if there are any that are unregulated. In any case, with either 3.3 or 3.7, as bruiser said you can use LR. They are typically rated at 1.8 ohms +-0.2. If they are less than about 1.5 ohms they will mess up your
batteries. Getting a VV battery like the Twist or Spinner will eliminate the need for LR because you can just turn up the volts instead of lowering the ohms.
Best of luck with it!