Current sensing ... Options ?

Discussion in 'General Electronics Chat' started by Dyslexicbloke, Sep 21, 2012.

  1. Dyslexicbloke

    Thread Starter Well-Known Member

    Sep 4, 2010
    I am about to update my PV control system along with the standby genny and a few other bits.

    I want to sense current in various locations within the system, some small and one or two relatively large.

    I was wondering if anyone has experience of these?


    The other option that I am considering is to use the voltage drop in the connecting cables and amplify that with a FET based op-amp.

    I will need an output from whatever sensing device I choose of 0-5v to be compatible with a uP

    I am interested in opinions on the devices pictured, the small one is an ACS712, as well any any other suggestions you may have to accomplish the task, measuring battery, inverter and PV currents.

    Thanks in advance
  2. JMac3108

    Active Member

    Aug 16, 2010
    I've used the Allegro ACS711 which is a very similar part to the ACS5758, the main difference being the 758 handles higher currents. It worked great and I had to no issues at all with it.
  3. JDT

    Well-Known Member

    Feb 12, 2009
  4. Dyslexicbloke

    Thread Starter Well-Known Member

    Sep 4, 2010
    I have a couple of units similar to that, 15A max, and I have to admit I am a fan but I need 9 of the things ideally, 2 of which need to be capable of 80A but still give me usable resolution in the sub 10a range.
    I also need 1 to handle +/- 100A on the main battery lead.
    I am considering using a hall effect unit, like the ones you suggest, for that so I can put multiple turns on it to get better resolution and then short them out with a contractor, the extra turns that is, when the current increases.

    Since cost is an issue I will probably go with the cheep chips for the smaller currents on the individual PV circuits. I will only need 10A full scale in one direction.
    These are basically just to diagnose problems, shading, dirt bad connections.
    Finite accuracy isn't that important as long as they are consistent.

    I am also wondering about how they will handle a PWM signal, I expect I will need an integrator between the output and the uP but I am hoping to get away with a passive R/C circuit, I can always use a high impedance opamp configured as a voltage follower to buffer the input if I run into issues.

    I would be very interested in hearing from anyone who has tried to measure a pulsed current with either of these units/chips. the base frequency will be circa 500hZ