Richard Lange

ENGINEERING NEWS 🚨 Tesla has patented a clever charging line: a solid metal bar that packs twice the conductor into the same space 🆒 When a Tesla fast charges, a torrent of power has to cross a short stretch of the car, from the charge port to the battery. That stretch must stay cool, stay electrically quiet, and squeeze past wheel wells and side panels, all at once. The usual tool for this job is a high-voltage cable, and a cable is flexible by nature. It can't hold a route by itself, so clips and brackets have to pin it in place along the way, and it needs clearance around it to shed heat. It also needs shielding so its electrical noise doesn't bleed into the electronics around it. As charging power climbs into the hundreds of kilowatts, the cable has to grow fatter, fighting for space the car doesn't have. Every terminal fastened onto a cable end adds another joint, and in a big cable assembly a failure can be hard to track down and costly to repair. Tesla's answer is to stop treating this path as a cable and build it as one stiff, three-layer bar. It starts with a solid rod of aluminum or copper. In the version drawn, its cross section is about 200 square millimeters, which works out to a rod roughly 16 millimeters across. Insulation such as cross-linked polyethylene, PVC, or silicone goes over the rod in a layer that can be half a millimeter to two millimeters thick. The insulated rod slides into a metal shield tube just wide enough to fit over it. Tesla then pushes the whole assembly through a compression die, which squeezes the tube down until it presses tightly against the insulation. What comes out is no longer three loose parts but a single bar. Because each layer is formed tightly over the one beneath it, the layers brace one another as the bar bends, so the whole thing can be shaped in three dimensions without coming apart. Like tubing in a pipe shop, the bar can be CNC bent along several axes, even at lengths beyond two meters. Each bend traces the car's interior, curving around a wheel well or slipping under the floor and side panels, hidden from the people inside. Tesla runs two of these bars side by side, one positive and one negative. Once bent, the bar holds its shape on its own. In some versions it is stiff enough to be supported only at its two ends, carrying its own weight in between, which lets the clips and brackets a cable would need drop out of the design. The ends get the same one-piece treatment. Instead of fastening a separate terminal onto the conductor, Tesla can forge the end of the rod itself into a flat tab and put a hole through it, so a bolt clamps it straight onto the charge inlet at one end and the battery connector at the other. The terminal and the conductor are the same piece of metal with no joint between them, which helps make the connection more reliable. The outer tube pulls double duty. It blocks electromagnetic interference and guards the bar against damage, while a rigid ground conductor ties it to the vehicle body, helping the car's isolation-loss detection system keep watch over the high-voltage circuit. Packing the metal this tightly pays off. For the same packaging volume, the bar can hold more than twice the conductor cross section of a cable and deliver twice or more the thermal performance. The design supports 350 kW charging at 400 volts while keeping the shield at or below 100°C, with fewer parts and less mass than a cable assembly. Plenty of owners may already carry one. In the Model 3 and Model Y, the DC fast-charging link from the charge port to the high-voltage battery is a busbar rather than a cable, so a version of this design could be riding along in cars on the road today. The same approach scales up. A set of these bars can wind through the battery enclosure of a semi truck, reaching out to battery connectors along the way. So when that torrent of power slams into the charge port, it doesn’t have to wind through a cable pinned down by clips and brackets. It races straight to the battery through two bars of unbroken metal, bent to hug the body and stiff enough to hold that shape on their own. Between port and pack, the power never crosses a single joint.