I purchased a 5A ACS712 module similar to this one here:
http://a.co/bs6iwABto monitor current of a 12V linear actuator with built in start and stop limit swtiches. Using the above module I wanted to know when the actuator has either extended or retracted fully (no current). I noticed that frequently during operation of the actuator the module will "get stuck" and report a consistent amount of current (around 0.18A), even when the actuator is completely disconnected. Resetting the Arduino still results in the same amount of current being reported (with the actuator disconnected from it) I would need to remove the power to the ACS712 module for it to operate correctly again however the same behavior reoccurs when measuring the current draw from the actuator (no load/force on the actuator). I read how magnetic fields can disturb the performance of the sensor so I re-positioned it several times to no avail.
One thought was that perhaps the actuator might be drawing too much current (>5A) however my power supply is rated at 3A and doesn't go into current limiting mode when started. When there is no load the actuator draws around 0.17A. It is rated at 0.65A.
I did try another motor which draws draws around 1A when running and over 3A during start which causes my power supply to go into current limiting mode however that motor works fine with the ACS712 module.
Here is what the waveform looks like when the actuator is running :
https://ibb.co/eJ0FsyI tried adding a 470uF capacitor in paralel with the motor and this is how it now looks:
https://ibb.co/eWfyCyAfter adding the capacitor the problem is solved and the ACS712 does not "lock up" as described above. Why does the motor noise effect the ACS712 I thought it is supposed to provide isolation? What is happening here?