Good idea on your part to go the 5 volt route. More flexibility and warmer vapor. But as TomCatt stated, yes, you need a regulator to bring the two 3.0 volt batteries down to 5 volts. 6 volts for most is just too hot whereas 4.5 - 5.0 volts has been widely recognized as the the "sweet spot" for vaping. I would also suggest checking our MadVapes.com. They also have a forum with diagrams. You can also call them and their staff will answer your questions.