Really, it’s better for the cables to be thinner if they have to be flexed. That’s because, as the diameter increases. the tensile and compressive stresses within the material increase the further the material diameter grows from the ‘neutral axis’ (I.e. an imaginary line that’s the perfect centre of bending).
Our power cables are high current test cable quality. Test cables (like you’d use on for a multimeter, etc…) these have multiple thin helically wound filaments, with a highly flexible silicone insulating jacket. These aren’t cheap; but we’ve learnt not to use any other, unless you want to be fixing broken conductors in the power cabling every other week.