Are the ferrites supposed to go over both wires and not just one?
The schumacher had, and I returned, A non snap on Ferrite on the output leads 3 inches from circuit board.
The larger ferrites on the both wattmeters leads did not cause any noise and are only 6 inches away from the one that causes the buzzing clamped over only one wire.
I replaced the original 12awg with 10awg to the circuit board, and use 45 amp anderson powerpoles. I did the 10 AWG mod hoping it would keep it from going to 16.4v and perhaps the display would read closer to actual voltage.
Neither improved, and now display does not say anything but 18.8 all the time. Kind of need some deisplay on the output to see if I pressed the right buttons for AGM and for 2 12 or 25 amps.