I'm having issues with the charge circuit on my 2002 civic with the 1.6L. Ive just swapped in my 4th alternator, because I figured I got a defective refurbished unit, but all only output 12.5-12.8v. After this last one I'm sure it had to be something else. Next I replaced the battery and engine ground but nothings changed. To clarify, I'm measuring 12.7v across the battery, but also from the alternator output stud to the alternator case (or any other grounded point). I was told to check the ELD module, but apparently the Canadian model doesn't have one in the charge circuit. What should I try next?

Edit: another piece of info that might be relevant. I hooked up an OBDii reader while driving and, no matter the RPM the battery voltage never got above the original 12.7v. It would dip when accessories were turned on but never exceeded.

Also the battery was replaced last year, the first time I did the alternator. At the time the alternatoe had the same issue but kept the battery topped up enough for me to get to work so I ignored it.