I have 2 mini Vivi Novas and 2 3.5ml Vivi Novas. I notice that when I vape the mini for a while, its out of juice before I finish my cup of tea. When I have the full tank though, that thing lasts forever. Whats the deal with this? Its only 1ml difference but the time difference is intense. Do the smaller ones retain heat better or something, giving more vape per hit? Am I crazy?