How to calculate total current, power, energy consumption from device?
No, your method is incorrect.

What you need to do is figure out the average current that is being drawn. By that I mean log the current that is being drawn over a certain period of time and find the average. 

You can then calculate roughly how long your battery is going to last by taking your mAh and dividing it by the average mA drawn.

I think OP is slightly confused over current consumption. Let us use an example:

A 9V battery, with a capacity of 600mAh is powering an LED with a series resistor. The total current in the circuit is 10mA. The average current is taken every 1 minute for 10 minutes. Each time it is 10mA. This means the total current is still 10mA. It does not add up. Do calculate how long the LED will be illuminated for, you simply take the 600mAh, and divide it by your average current drawn (in mA). Thus, 600/10 = 60 hours.

Of course, this will only give you a rough figure. There are losses throughout that time, so some places, such as HERE will have an extra *0.7 at the end of the equation, thus making your battery life (600/10)*0.7 = 42 hours. This is to account for losses that will inevitably happen during the lifetime of a circuit.