Advice on best current sensor needed for 30A

  • Hello All, I need some guidance on the best way forward with my current project. I am wanting to monitor the battery current from my 12v battery which will not be over 30 Amp.
    This needs to be bidirectional as it will be either pulling current out or charging current in.
    I have a shunt resistor which gives a 75mV voltage drop across it
    I have also tried the hall effect sensors but they are not very reliable at low currents. I would like to at least measure down to 0.5A or even lower if possible.
    So I have been looking at dedicated sensor boards and was liking the INA219, but this will only measure max 3A. If I remove the shunt resistor on this and put in my shunt resistor then it will take the current across the shunt but I am not sure this will work without more work done. This INA219 states it can read +/- 320mV and the shunt resistor gives out +/- 75mV.
    Is there a way to get what i am trying to do easily with this chip or is there a better way to get this done with an alternative device.

  • Mod

    @Motorhomer I’m none pert but I think replacing the resistor will work. You’ll just need to adjust the values, either manually or by following the calibration calculations in the INA219 library.

    You’ll be limited to 75/350= about 20% of the resolution, but depending on your use case that might not be a problem. If it is, maybe you can get a 5x smaller resistor?

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