Pushing 500 amps through a hand-held connector is, on paper, an unreasonable thing to ask a piece of consumer hardware to do.

The mass problem

A passively cooled 500-amp cable would weigh roughly 4.2 kilograms per metre. At a usable five-metre length that is 21 kilograms — heavier than most checked airline luggage.

How the loop works

Inside the Combo Rapid jacket runs a sealed circuit of dielectric fluid, driven by a brushless pump in the base of the connector. The fluid absorbs heat from a finned aluminium sleeve, then dumps it through a low-profile radiator in the strain-relief boot. The whole loop is hermetically welded — there is nothing to service for the life of the product.

Engineering is the discipline of choosing which compromise you are willing to live with.