Current Drain measurement, DC vs RMS (what to use to calculate current drain)

[faisal78]

Hi
I have the below measurements for device for my home project.

As you can see, there is a significant difference in current drain between DC and RMS.
I have a 1000mAh battery in which I need to predict this current drain usage, but which do I use?
Does the battery actually use DC or RMS?

 

[KerimF]

RMS value is for AC or varying voltage/current to compute power.

A battery is a DC voltage source, and it is discharged (or charged) following the formula:

Q = Idc * t
where (Idc) is the average current during time (t).

 

[faisal78]

Hi, Is there any application from a current drain point of view do we use RMS?
E.g., would I use RMS when measuring current drain from an Audio PA driving a 1kHZ tone?

 

[KerimF]

If the element of which you measure the RMS current (Irms) is resistive (say R), we can apply:
P_element = Irms * Irms * R

I wonder if it has other usage, I mean the RMS value

 

[iop95]

Capacity of a battery is stated in datasheets for constant current or constant power. In this case, current is not constant, so best method to estimated back-up time (or capacity battery for a requested time) is by energy (or power) requested by load. Need to take care for maxim current to be below maxim battery discharge current (average or RMS current may be below, depending of PWM duty).