Measuring Fuel Cells with a Multifunction DAQ Module or Device

Updated Jul 23, 2018

Reported In

Hardware

  • USB-6225
  • Multifunction I/O Device

Issue Details

I have 40 fuel cells that I need to measure and each cell provides voltage up to 0.8V. I have a USB-6225 that has 80 analog inputs. Can I measure my fuel cells with this DAQ board?

Solution

In this kind of measurement is important to know the Common Mode Voltage that the board is able to handle. Reviewing the USB-6225 specifications lists a +/-11V (Signal + Common Mode).
As the maximum voltage that you will have is 0.8*40 = 32V, the measurements cannot be performed directly with your configuration. However, there are some workarounds:
  1. Create custom signal conditioning circuits for each cell that eliminates the Common Mode Voltage
  2. Create custom signal conditioning circuit that allows the common voltage be in range with the board. If the cells voltage was 0.4V instead of 0.8V, the USB-6225 would be able to handle the common mode voltage. Setting the reference in the middle of the cells, the common mode voltage will be 0.4*20=8V upwards and -8V downwards. 
  3. Use specific modules to measure fuel cells like the NI 9206.

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