Originally Posted by Travis Covington
This is exactly what I was referring to. I have used 4awg wire on robots since 2000 and have come across all sizes of supposed '4awg high strand count' wire. If I am making a concerted effort to upsize my wire for current, heat and voltage drop reasons, I am going to use the largest stuff I can that still fits in the 4awg ring terminal (which has a significantly larger OD than the .22" SB50 ID). For reference and comparison, the 4awg Molex ring terminal we use on our batteries has a .280" minimum ID for the wire.
Good info to know but I'm not sure what else to say...
The wire we have matches the specs listed from PowerWerx for their 4 awg wire as well: https://powerwerx.com/welding-cable-epdm
I do agree though about not all wire being equal. The larger stuff I've seen listed as 4 awg and held has not been OFC or bare copper though, it's been CCA - it's lighter but it doesn't conduct as well based on the measurements I've seen and what I've read.