If anybody want to take the touch on this here is my script explained as best as i can.

The script is divided in to 6 segments, this is to simulate the dual LOG scale of the battery voltage vs capacity.
Download the zip in post #3 if it is easier to follow.

1 segment:
if voltage is greater then 4050mV then battery % = 85 + (mV - 4050) / 12

2 segment:
if voltage is greater then 3900mV and less then 4050mV then battery % = 70 + (mV - 3900) / 10

3 segment:
if voltage is greater then 3800mV and less then 3900mV then battery % = 50 + (mV - 3800) / 5

4 segment:
if voltage is greater then 3660mV and less then 3800mV then battery % = 15 + (mV - 3660) / 4

5 segment:
if voltage is greater then 3600mV and less then 3660mV then battery % = 5 + (mV - 3600) / 6

6 segment:
if voltage is less then 3600mV then battery % = (mV - 3300) / 60


INFO: 4050mV = 4.050V

I'm a bit strapped for time lately, so if anybody want to upgrade the battery widget in question here's the recipe.