Multiple acs758s and noise

Other Hardware Sensors
1

Hi all,

I have an arduino uno that is sampling current and voltage from multiple sources in an off-grid setup.

I am sampling :

  1. battery current (bidirectional, 200A max) ACS758 200B
  2. solar current (from 2 different regulators, 100A max each) ACS758 200B and ACS758 100B
  3. turbine current(50A max) ACS758 100B
  4. genset current(100A max) ACS758 200B

( I am planning to replace all sensors to unidirectional barr the battery current one )

in addition to

  1. battery voltage (barring catastrophy, 23v to 32v)
  2. turbine voltage (0v to 150v)

The environment is possibly very electrically noisy inside the distribution box near the solar/turbine regulators.

The arduino has an ethernet sheild to provide networking to the outside world.

Also, the arduino takes care of turning on/off 2 ssrs.

  1. to turn a 240v outlet on when batteries are full and off when below a set point in battery capacity
  2. to turn off and on turbine brakes depending on many conditions

To be clear, this is an existing installation and has been working 24/7 for about 3 years. My issue is that the data (sent from arduino to local server every 10sec) that I am collecting from it is noisy..

I have attempted to follow the datasheets for the ACS758s but I don't know for sure what happens when connecting up multiples powered from the same bus lines

also , the datasheet is not clear as crystal with regards to output filtering so I was flying blind using a bit of trial and error when doing component picking.. I did testing with only one sensor and I am thinking that is part of my issue. Also, it seems the uno can produce a bit of crosstalk between the analog input pins so I am sort of chasing my tail...

so currently using (per current sensor)

  1. 0.1uF cap between 5v rail and gnd
  2. 10nF cap between output and gnd
    3 4.7k resistor between sensor out and arduino analog in pin

voltage sensing is done with voltage dividers

Arduino is powered from a wallwart, switchmode 7.5v ..

The reason for the questions now is because I am planning to make a new custom sheild to replace my v1.0 sheild and now is the time to get these things right..

Any advise ?

Thanks in advance

2

The 10nF needs to be at the Arduino side of the 4.7k resistor to suppress line-borne noise.

Shielded cables for all your sensors would be good, shield grounded only at Arduino end.
Keep sensor wiring well away from high current wiring.

3

Thanks for replying MarkT

Ill try to replace all of the sensor cables with shielded cables..
Is there a particular type of cap I should be using for the 10nF line caps ?

So with power n ground for each sensor. Each gets its own .1uF on the sensor side, right?