Hi Ioannis!
Thank you and you are very correct. What will probably be necessary is to add an external 3 second delay to measure the zero point each time time circuit is powered up. That is, power up the PIC, wait 3 seconds, then add the load. Where I have become very stuck is in what I call 4994 land. At 50 amps the A/D will be giving you value of 2987. Subtract a zero point of 490 and you get 2497. Times 2 and you get 4994. It seems no matter what I do this number keeps showing up!