I have an active cellular plan but I haven't used it much. My watch is connected to my phone 95% of the time. The battery life is decent, but not quite as good as my series 1 was. Like I can get a full day out of my series 3. Sometimes I have been able to get a day and a half or two days but it just depends on how much a use the watch. My series 1 however, would last me two days no problem. So I just think it's the LTE that kinda drains the battery a bit.