user53332: I want to measure power consumption and calculate the mAH value to know how much time would my battery can run the circuit. 
I only got a multimeter and DC power supply.(Im not sure if this is enough to measure)
My project has a temp sensor and measures it every 15 mins. It's going to deep sleep mode and wakes up again to measure.
So how to measure the mAH for this circiut?

user34529: I suggest using a second Arduino to make yourself an "Energy Meter".
Get a very small power resistor (0.1 Ohm) and power your project through it.
Second Arduino will measure voltage drop on it and that way you can get the current that goes through it using Ohms law. You can also measure the battery/power supply  voltage. Knowing those two values and micros each loop you can calculate actual hourly power consumption of the device.

53332: <p>I want to measure power consumption and calculate the mAH value to know how much time would my battery can run the circuit. 
I only got a multimeter and DC power supply.(Im not sure if this is enough to measure)</p>

<p>My project has a temp sensor and measures it every 15 mins. It's going to deep sleep mode and wakes up again to measure.</p>

<p>So how to measure the mAH for this circiut?</p>
 34529: <p>I suggest using a second Arduino to make yourself an "Energy Meter".</p>

<p>Get a very small power resistor (0.1 Ohm) and power your project through it.</p>

<p>Second Arduino will measure voltage drop on it and that way you can get the current that goes through it using Ohms law. You can also measure the battery/power supply  voltage. Knowing those two values and <code>micros</code> each <code>loop</code> you can calculate actual hourly power consumption of the device.</p>
