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Measuring thruster current with WCS1800

Hi Folks,
I am using WCS1800 current sensors to read the current consumption by one thruster, its range is upto 35A for DC currents so it is in our working range 1A/66mV. It is working almost accurate as I have tested with a 5S Li-In battery and battery-charger given by Bluerobotics itself, the current value for charging which display on LCD of charger exactly matches with my sensor output, so I found it is perfectly calibrated. But the same sensor If I am using to measure the current consumption of T200 then I am getting erraneous value and that too around 50% error. Anyone please can help me out to find out the issue behind this. I think it was EMI or RFI from battery, so I made my thruster ESC apart from battery around 2 mts disthance, but still I am facing the same issue. Or if this issue is because the switching process happening inside the ESC or anything else.

Thanks in advance


The thruster speed controller pulses power to the motor as it controls the speed. That happens at a very high rate and if your sensor has a very high measurement bandwidth then it can detect these rapid changes and get noisy or incorrect measurements. If this is the case, I would recommend using a hardware low pass filter to smooth the measurement. For instance, an RC filter with bandwidth of 10 Hz would to a good job of smoothing out this measurement.

The WCS1800 has a bandwidth if 23 kHz so I think this is the cause.

For example, here is the low pass filter we use on our power module for the same reason. The “I_SENSE” connection goes to a microcontroller that reads the measurement.

I hope that helps!