Huh, I'd thought the Aspire was VV, but appears not in this link. Any idea what voltage the non VV are, or is there a way to find out in specs? My norm is to use 3.2 pretty much exclusively and only ramp up to 3.7 when a coil nears end of life. I could probably tolerate 3.2 in non vv, particularly if I'm using a better tank/coil system, but would be fearful of it being too little voltage as a permanent setting.
The K2 battery is not VV. It is, however, supposedly, a 4.8 volt fixed voltage battery as stated at the very bottom of this page. However I have tested supposed fixed voltage batteries in the past that were not actually fixed voltage, so YMMV. I'm not saying they are lying (they probably aren't), but many of the fixed voltage batteries I have tested were in fact lies, they were just regular old 4.2v batteries with unregulated voltage (therefore the vape gets weaker as the battery depletes as you vape it).