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...
eBike: Q100H on 16S with Phaserunner FOC Controller
eMotorscooter: Vectrix VX-1 on 36S
eCar: Mitsubishi Outlander PHEV... Waiting for warranty to expire
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After 5 builds, the best advice I can give, is start with high quality products. I prefer http://www.ebikes.ca