I have a dear friend who is a couselor and she works all day in her office plus has things to keep her busy at home so she has been after me to get an electric-cigarette for her. She really liked my 5volt mod but I don't think she should start with a homemade mod as if it had trouble she couldn't fix it or get it going. First I said a 510 but she don't have time for all that filling and changing batteries so as I use a kr808d-1 carto on my 510 5volt passthrough most of the time I thought a V4L or a kr808d-1 but how is the batterylife on that? Give me or I should say her some help please. What do you think? Oh and I showed her ECF but she just hasn't had the time.