There were (are) several versions of the basic DNA-30D. Some have a minimum voltage of 4,0 V. Some others 3,5 V, this happens according to the several specifications floating around, dates of manufacturing, and so on. My guess is that there is some limited capability of going under battery voltage, but very limited, as if it were a fixed pre-stabilizerf voltage step to that precise voltage (Evolv technicians know better, of course). DNA-20D / 30D were (are) not designed to a full step-down capabilitiy, I suppose because the 'less-than-7W' atomizers class was considered in the verge of extintion....
Well, it wasn't, and the newer incarnations (DNA-40D and Innokin SVD 2.0, and the next DNA-25D) would be (are) able to a truly step-down, even down to 1 W (in the temperature controlled, wacked up in the start of each puff DNA-40D).
If you add the uncontrolled crowd of cloned chips (Cloupor, Kangside, and all that jazz...) the picture gets definitevely blurred. They effectively clone the aspect and behaviour (well, more or less) of the original ones, but also have disparate limitations on resistances and limiting voltages...and some clones have even something funnier: they 'rattle-snake' when you set power with a final voltage outcome below 4,0 V.......!
The rattle-snaking curse......always haunting us even in the brighter days.....