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Current consumption measurement using DAQ

I have battery system of 48V for electric vehicle application. I want to measure and log current consumption of my IOT board in sleep mode. Can I use NI DAQ for this purpose. Which card would be suitable for this application. I want to connect it in series with my  battery system similar to multimeter in current measurement mode. Please suggest?

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You can use DAQ to measure current along with an external current shunt. You need to select an appropriate current shunt and use it for low side current measurement.

 

What is the range of current you intend to measure, sleep, normal, burst?

Santhosh
Soliton Technologies

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Can I connect 9203 in series to positive side of supply like multimeter for current measurement.

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Not sure I understand your comment.

 

Typically, we put the shunt in series after the active load we need to measure and we connect the DAQ to the shunt as a differential pair to measure voltage just at the shunt (and I = U/R). This generally happens in cascade as we can have a main Power Management IC providing supply to loads or other PMICs (basically, we are checking a complex power tree, that gives us the load but also helps checking the PMICs efficiency). Of course, if the last shunt in the cascade is connected to the ground, you could avoid being differential (and save 1 channel) 

 

Shunts are typically 5, 10, 20mOhms (to add only few % of load to the component):

  • a high value is better for small current accuracy
  • a low value covers a higher range before going to a higher DAQ input range (thus better accuracy at high current)

Thus the previous question about the max current value.

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NI 9203 is intended for the current loop signal (4-20mA) measurement, despite that you can use it for your purpose as well as long as it is operated within the specifications.

 

Though you can, I would advise against doing so, especially since you're dealing with 48V equipment whereas the typical line voltages for 4-20mA loop does not exceed 30V.

Santhosh
Soliton Technologies

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