If we are attempting to determine its battery usage we should each post the "standby time", "talk time" & "Device usage" hours/mins listed under the Information tab in the power settings. Once we have enough posts we can take the average of all devices and get a more accurate figure in battery usage.

Example (my current power consumption status):
Standby Time: 02H:20M
Talk Time: 00H:00M
Device Usage: 00H:07M
Battery Percentage: 100%

I believe we are going to want the usage details for a battery that has already been used down to a lower charge. Ex: 10-30% charge left.

Now we would have to do this after a complete charge. It's not perfect or an exact measure for the battery consumption but its a start.