The 300A hall transducer can be ranged to 100A by simply looping your power line through the torus 3 times.In effect the sensor then detects the flux produced by 3 x 100A and "thinks" there is 300A flowing.Or to 75A by looping 4 timesIf you set Vref low enough then you get full resolution provided you aren't interested in measuring reverse current flow.Your original enquiry stated "reasonably accurately" What do you consider that to be.Resolution can never be better than 0.1% and component tolerances probably reduce accuracy to around 1%
The reason I asked about location is the shunt needs to be the last thing in the ground lead, right at the Batt neg. terminal if possible and Arduino GND connected to batt neg., but sounds like you already know that. Single supply op amps are cheap and easy to use, would not be too difficult to rig up a 33 to 1 amplifier.Like this:
80Amp and an opamp gain of 34 gives ~418 A/D values.Lowering the 1k resistor to e.g. 470ohm could give you twice that resolution.
Are you sure you can safely ground (to USB/computer/mains) the negative wire on the solar cell side?
High-side measurement (shunt in the positive line) could be a safer way.https://www.adafruit.com/product/1164Leo..
80Amp and an opamp gain of 34 gives ~418 A/D values.Lowering the 1k resistor to e.g. 470ohm could give you twice that resolution.Are you sure you can safely ground (to USB/computer/mains) the negative wire on the solar cell side?High-side measurement (shunt in the positive line) could be a safer way.https://www.adafruit.com/product/1164Leo..
But using a hall torus would give 'perfect' isolation and be totally "safe"
@Wawa, I looked at that adafruit part you mentioned. It maxes out at 5 amps, how would one use that with the larger shunt?
Just connect it to the larger shunt.The big shunt is 0.075volt / 100Amp = 0.00075ohm.The 0.1ohm shunt on that breakout board will be the fly on the elephant.100Amp through the main shunt is 0.075volt / 0.1ohm = 0.75Amp through the breakout board shunt.Leo..
If you decide to use hall sensors...You could use two 50Amp hall sensors (and two analogue inputs) if you split/divide current over two parallel cables.Leo..
In my general practice, I have tried to avoid that if possible. Inevitably over time, one connection gets loose/corroded/etc. and throws the load to the other leg, with spectacular results. 30,000 amps dumped onto a single 4/0 cable is not something you quickly forget. It wasn't my doing, as I was just a helper at that time, but was magnificent....put the 4th of July fireworks to shame. Who knew molten lead and copper could spatter so far and stick to so much?