That is strange because I have both a BP and a vv woodvil. I can get a full day use out of each of them. I only shut them down when I go to bed for the night or putting them in my pocket or purse.
Are you keeping them in sets and rotating the tops and bottoms with each use? Are you letting them rest before charging them and before you re-use them?
How many ml. of e-juice are you going through? I use about 3ml. a day six uses 6ml a day, I thank everybody uses there PV differently.