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.
I see the same thing. I have seen online specifications for 6 AWG wires and lugs ranging from .167 for single strand to .25 for the 1000+ strand that I use. I figure more strands leaves more air gaps around the strands, but when crimped properly the air gaps are eliminated provided a nearly solid wire under the crimp. Cutting some strands to fit in the .22 SB50 lugs slightly increases resistance over a length of less than 1/8". I don't worry about this because it is less significant than using 50 AMP connectors on 75 AMP AWG 6 wire in front of a 120 AMP circuit breaker on a application that pulls over 200 AMPs for up to a few seconds! I would use #2 wire in SB120 connectors but this is less important than having a driver that is 5% better.