Well, thank you all for the kind inputs. In regard to the batteries charge, this sophisticated device notifies me upon switching the power on that batteries are fully charged by the extra beeps and by the way I was detecting for hours and no low battery sign popped up. Back home, l removed the rod and discovered a tiny looseness of the coil’s connector (the coil is a 10X12 original without any damage, l love and take care of my baby) , so I did tighten it and cleaned all before setting it back together. I observed a transformer room on the side of the road along with couple power lines but I was more than 100 feet away from these and the loud interference noise was still persisting. Provided I had not been back to this particular field, I’m now gearing up for another site in a different town, so let’s hope and see if the problem was simply a passenger issue. Cordially