Measuring Direct Current Via a Computer Interface.


Introduction: Measuring Direct Current Via a Computer Interface.

About: Update 12 September 2017: A very special thanks to Sam Elder, a manager here at Instructables, who tracked down the cause of my lost publications and fixed the issue. Take a bow Sam!

I always wanted to remotely measure the current from my mppt solar charge controller and into my inverters but the idea of using current shunts was not feasible since I cannot amplify the millivolt signals across them.

Along comes the Honeywell 72amp hall current sensor. It gives 33mv per amp. I powered Mines from 12 volt dc.

Step 1: Wiring the Hall Sensors.

These hall sensors can measure ac or dc but need 6 to 12 volt dc to work. The cutsheet shows the wiring. Looping a wire several times through the hope will increase the sensitivity.

Step 2: Run the Signal Cable.

I used shielded cat5e cable to send the sensor outputs to my labjack u3 at my pc.

Step 3: Install the Hall Sensors.

Installation took some skill and I put on the relevant wires. I made 3 loops for the inverter dc cable and 2 loops for the mppt dc cable.

Under maximum load the wiring holds up nicely. Note the 6mmsq wire per sensor to pass up to 70 amps. This goes to show that the DC rating of a wire is significantly higher than the AC rating. Of course I did my research into the sizing needed. Attached is the table for DC rating for 90C cable.

Step 4: Add Signals to the FLOWSTONE Software.

I used FLOWSTONE to create the software to control my entire home. As you can see now there are guages to display Currents. Also by volts x amps I can display power! This screenshot I took at night so the mppt current is 0.

To show the actual current value I used subtraction and multiplication to scale to sensor outputs to the real time current values.

Easy way to reliably measure high dc Currents.



    • Clocks Contest

      Clocks Contest
    • Creative Misuse Contest

      Creative Misuse Contest
    • Oil Contest

      Oil Contest