Rob,
Thanks again for the reply.
sorry for the "map" thing. I was not familiar with the function, so I just guessed since u did not mention the environment. Thank you for that .
Now, let me tell you what exactly I am trying to acheive.
I am trying to measure the current withdrawal from my battery. Its (9.6v, NiCd,700mAh).
At very first, I connected ACS 712 in series with just one motor .(since this is the major load in my rover. Motors are connected to Adafruit motorshield.) I was getting fluctuation in the DMM and ACS readings as well.
So, further I connected ACS 712 in series with battery and that in series with DMM,with that, the DMM readings are not fluctuating, but ACS readings are still fluctuating. I am sure this is because of the PWM technique Arduino uses. Now, one more thing here is, if I increase the Vref to 5v by rotating the Vref pot on ACS 712 at its max position and making the gain maximum, I constantly get the value 1023. No fluctuation. (which really does not make sense.) If I set this pot to min
the values are again constantly zeroes.(catches my nerves..!!!)
Further, I just tried to play with the sensor and kinda tuned the both pots just to get some sensible values on serial monitor. I got the values mentioned here for the constant current of 0.48A (current measured on DMM)
For 50 rpm,
0
0
121
219
189
204
220
0
0
141
198
216
191
193
0
0
Now, If I am correct, these values are representing the voltage and not the current since, the output of the ACS712 is analog voltage. I also know the current (bcoz of the DMM), but I do not know the voltage values, as I have tuned the pot (Vref and Gain) at some random position and now, I am not able to understand what is Gain value and what is Vref value!!! having said that , how do I calculate the voltage values from the digital numbers I am getting ?
If you think there is something wrong my set up or strategy to measure the current or if some of my concept is wrong let me know.
Hey, by the way, where did u get the power factor thing into this 
..I am running a DC system.
Thanks again,
Amit