Q:

What affect more the battery time: mA or V?

I will create a small circuit with a battery and vibration motor. I will use a 3V coin battery with 100 mAh.
So, I can use a motor:

With 3V and 75mA
With 3V and 150mA
With 1.5V and 75mA
With 1.5V and 150mA

What will drain less energy of the battery: 3 < 4 <= 1 < 2? (3 drain less than 4 and drain less or equal to 1 and drain less than 2). Is it correct?

A:

The most convenient way to determine power use will be to simply multiply the voltage by the current to give power, so from lowest to highest (ignoring the equal values) we have:

1.5V x 75mA = 112.5mW
3V x 75mA = 225mW
1.5V x 150mA = 225mW
3V x 150mA = 450mW

However in practice if you want to go from 3V down to 1.5V you'll need a step-down converter, even a very efficient one will still add say 5% to the power consumed because of the quiescent current and converter efficiency so then that will change the order a little for one of the 1.5V options:

1.5V x 75mA x 1.05 = 118mW
3V x 75mA = 225mW
1.5V x 150mA x 1.05 = 236mW
3V x 150mA = 450mW

You should also check the datasheet for the coin cells you're using to check the maximum recommended discharge current. For example the table at the following site suggests that for a CR2032 even for pulsed operation 25mA is the maximum along with 5mA for continuous current.
http://www.eemb.com/Li-MnO2_battery.html

