Such is why I have not recommemded anything but 200-ampere rated charge dividers. Quicksilver has a massive 600 ampere amplified relay driven relay driven by a rectified stator signal. The Monmouth relay is rebuildable utilizing a 2.75" x 3/8" copper disc and 1/2" copper bolts. The contacts do indeed get pitted and black. I rehab with copper-tin bronze.
Regardless every inch of charge path must be proofed including the coach AGM battery - alt/reg. Can be done easily. Process of elimination. If everything checks out but the battery. Oops let's not go there...