Many people love the EPDCC on the e-power, but you might need a little more power than that battery and regulated switch can provide. You have a VV box, why not get an ego-510 adapter and use that EPDCC on the mod? I run them at 4.3-4.5v and they hit great that way.
I had one but it got stuck in a EMDCC and i couldn't get it out . gotta re up.