I had that too.Mine too. And its even more impressive that it keeps increasing day by day.
Here, I copied it from the Battery report generated by powercfg
Yes, my SP3 now has 44 Wh battery!
Try to beat that! lol
Mine is the i3/64 by the way. Im curious to see if the i5 and i7 model had larger battery, since they stated that all models should have similar battery life.
I have the i5, so it has the same battery.