Compact 0-80A Automotive Ammeter
The latest adddition to our line-up of PIC-based automotice projects. Build it and keep tabs on your car's electrical system.
The cable is resistor. about 0.001 ohm. For 80A the voltage is I x R = 80mV.
Your uC can calculate current via this formula or you can use a voltmeter by calibrating multi turns trimpot. For example you can use 70107 voltmeter circuit. It has 200mV full scale.
Perhaps you may need a op-amp multiplier for scaling .
Ok. But it is not necessary to know exact value of current! even 5% sensitivity enough for automobile panel. 30A or 31.3A not important. This panel is not scientific meter. also you need calibrate it by real multimeter for first time.