dear Brian sir,
I was working on it... and come up with it.. (as shunt makes huge loss in case of 5v scale..)
i will use software for calculation and i need high 20-30A where low 1A atleast... more less, better... but i want to reduce complexity also... so since about charging a 100-200AH battery, i'm considering of 1% of total 9so for 100ah, 1A) as full charge state and to go for float voltage... now, in this case, 1A is okey with me...
So if consider (at first...) 20A (later upgradable upto 30A), then i can use .1ohm 5w resistor total 4 nos in parallal... means
Code:
|--vvvvvv---|
----|--vvvvvv---|----
|--vvvvvv---|
then as per KCL, each .1ohm will carry 5A (for 20A). Now it i still stick with my previous charger with 5A equals to 500mV at shunt, then for 20A, i'll get .5V. Means as per software calculation, when ADC sees 500mV at shunt, then .5V*4 = 2.0 means 20A
Now for lower part, since 5A makes 500mV, 1A will make 100mV for one resistor, the final shunt (4||) will carry 1A where each resistor will carry .25A. As per math, for 1A, it develops 100mV (single resistor) and for .25A, it will be (0.1x0.25) = 0.025V = 25mV. This is okey for me as currently ADc can take minimum of 4.8mV. So i can even reach near to 500mA.
So do you suggest me to use a 0.1ohm||4 (as at 5A full, it only develops 500mV), altogather it will still develop 500mV at 20A.. So math will be ADC volt x 4 x 10.
Power rating 5W here...
Please suggestion.... Also about compansating with the regulator output and drop of shunt, i'll use lower side measiring and i'll have to calibrate the regulator on + and - terminal (not the + and GND) for a 13.8V calibration right??? (please tell me a bit more on this calibration..)
Mishu~