Could this be achieved using the Arduino (and preferably my existing shunt) without the need for a polarity reversing switch?
I have a 100A 75mv shunt across the negative terminal on the leisure battery in my campervan, and a simple digital ammeter which measures current flowing out of the battery. I also have a switch installed which flips the polarity on the meter and allows me to measure current flowing into the battery - from the alternator when the engine is running, a solar panel or mains hookup when parked up.Could this be achieved using the Arduino (and preferably my existing shunt) without the need for a polarity reversing switch? I'd like to throw up a value on an LCD display which automatically moves from positive to negative as current flows into or out of the 12v battery.Thanks in advance!
Do you feel comfortable building the "Improved Absolute Value Circuit" seen here ...http://www.analog.com/library/analogdialogue/archives/44-04/absolute.html
QuoteDo you feel comfortable building the "Improved Absolute Value Circuit" seen here ...http://www.analog.com/library/analogdialogue/archives/44-04/absolute.htmlThat is an interesting circuit, but the gain is only 2, which won't really help for the OP's application. It is certainly possible to change the resistor values, but they would have to be very high precision for the circuit to work correctly. The advantage of that particular circuit is that all the resistors are already present in the package, and are trimmed to 0.02% tolerance.
Careful, that is only rated at 100A. The other one they sell is only rated at 200A. A starter, depending on the vehicle and ambient temperature, can easily draw upwards of 350A.You can't just parallel a few of these, not without putting a lot of work making sure one doesn't end up hogging the current and burning up anyway.