7" of 4 AWG @ 600A = 51 watt loss
7" of 2 AWG @ 600A = 33 watt loss
7" of 4AWG @ 200A = 5.7 watt loss
7" of 2AWG @ 200A = 3.6 watt loss
7" of 4AWG @ 80A = <1w loss
7" of 2AWG @ 80A = <1w loss
As long as your times are accurate, I'd say dustNbone is spot on. I would not like to see 51w of heat dumped across just 7" of cable for any significant period. Short cables = low resistance, but short cable = smaller heat sink...