A few weeks ago (almost 2 yrs to the day I purchased SP3), when on batt, my SP3 only lasted about 30 min. Upon further investigation, I discovered that my batt efficiency had deteriorated to the point that it could only hold 30% of its total charge. Since my SP3 was my daily driver at the office it was primarily docked (95%) of the time and undocked for meetings etc. I have discovered that leaving your device connected to AC does in fact degrade the batt. So, I would like to ask the group, "How do you get through your day, when the SP3/4 is docked? And what effect has/have you noticed on your batt efficiency?" p.s. I have replaced my SP3 w/SP4 and I'm not looking to repeat the same batt issues.