V V controller for single 3.7 batt

Just finished making one of the MadVapes vv box mod and just realised it runs 2 14500's...not 2AA's (dumb arse) wrongly assuming that it would boost the volts.
Just to see if I'm getting me head around all this stuff if I want to build a vv that runs off a single 3.7 so do I need something like this ??
or do I need to do a lot more research

DC-DC Converter Buck Boost Module 3-35V to 1.25-30V Step-Up Step-Down Converter

 

That unit will work, BUT with a single battery it wont work very well. I have a few of them and tried with a single cell. Battery life was not good on higher than input voltage. Better with stacked batteries for sure and then it works well. If Stoney catches this he will be better with the tech side of it?