algufo
- 18th January 2006, 08:58
I'm a newby in the PIC world but I've been fashinating by the power of these small incredible devices.
I'm building an application to control charge and switching between thetwo lead batteries in my motorhome. The PIC I'm using is a 16f876.
I have to measure the current fowing in (charge) or out (discharge).
The batteries are 12v (nominal, up to 14,8 real) and currents may be up to 40 AMP.
I thought to use a shunt of 0.01 ohm th have 1mV/Amp.
So I tried to measure the 2 voltages at the end of the shunt and make a difference.
The problem is that I notice the reading quite unstable. Maybe that the 10bit resolution isn't enough to measure the difference of 1 mV.
Do you have any suggestion (maybe using Vref or some different methodology)?
Of course I wouldn't use an higher value for the shunt for not dropping too much the voltage.
Thanks
I'm building an application to control charge and switching between thetwo lead batteries in my motorhome. The PIC I'm using is a 16f876.
I have to measure the current fowing in (charge) or out (discharge).
The batteries are 12v (nominal, up to 14,8 real) and currents may be up to 40 AMP.
I thought to use a shunt of 0.01 ohm th have 1mV/Amp.
So I tried to measure the 2 voltages at the end of the shunt and make a difference.
The problem is that I notice the reading quite unstable. Maybe that the 10bit resolution isn't enough to measure the difference of 1 mV.
Do you have any suggestion (maybe using Vref or some different methodology)?
Of course I wouldn't use an higher value for the shunt for not dropping too much the voltage.
Thanks