[kiettyyyy]

Originally Posted by philso

I'll take your word that the crimps were good and the screws and nuts are tight. What sort of motors did they have in their drivetrain? How much wire was removed from the loop in total?

My gut feeling is that if cutting out a few feet of wire made that much difference (you probably didn't cut out 12 feet or even 6 feet if they started with 6 feet), they are probably still just above the brownout threshold of 6.8 V. It is likely that they still have some other issues such as batteries with high internal resistance and that it is likely that their brownout problems will return.

6 CIM drivetrain and a couple of minicims on an auxiliary mechanism.

The loop was 6 ft for both black and red wires (12 ft in total). When I told them to chop it off to a minimum, I came back and saw that they had just under 1 ft for both black and red wires.

The problem went away.

High current draw across 6AWG *DOES* result in a large voltage across a long span of wire.

Physics doesn't lie unless you do the math wrong.