I would really like to get my dad an e-cig and I think the KR808D-1 model would be best for him. I know he would want something relatively hassle free, and I know he wouldn't like messing with juice or carts because he is farsighted (can't see close up). So my question is, roughly, how long would the original juice in a cartomizer last? He is about a 3 pack a day smoker so I kind of want to know how many cartomizers he would go through a day without refilling them. I'm not sure I would want to get him this model if he would be going through 2 packs of cartomizers a day. Then again, if I did get it, and he went through too many cartomizers a day, or if he didn't like it...I could always use it...that is a good thing.