Thank you for the explanation. Once I have a clear Wh or Ah value, I can transform my data to scale a batterie if required.
I guess I have the answer to my questions so if I still don't get it, it is because I ask the wrong questions.
I will try one last way.
In a DC circuit with a resistive load, my DMM read 10 mA. I can start a timer on my phone and read this for 1 minute, 10 minutes, 1 hour and so on. I will read 10 mA during the whole test. Base on the last reply, if I stop measuring after 1 minute, I should conclude that my circuit need 10 mA / minute. If I stop after 1 hour, I should conclude the circuit need 10 mA / hour. etc.
If I convert all these cases to mA per hour I will have different results.
600 mA / hour (when I stop after 1 minute), - an hour is 60 minutes,
10 mA / hour If I stop after 1 hour.
Base on the Device_Wattage example from Ron, I should do the following:
A- 10 mA * 12v = 0.012W
At this point there is still no unit of time involve since I am using the DMM reading and it is not scale to time.
Next is:
B- 0.012W * 5 minutes (I don't choose hour on purpose to try understanding) = 0.06W / 5 minutes.
This would be the power required by my device to run 5 minutes.
Then if I want the data for 1 hour I would do:
C- 5 minutes * 0.012W + 55 minutes * 0W = 0.06W / hour.
Finally I can obtain Ah and scale my batterie using :
D- 0.06Wh / 12 volt = 0.005 Ah.
please tell me this is it!