InDetail: KERS Cable and Connectors

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When looking at the installation of any Hybrid or Electric racing car, the bright orange cabling is a trademark feature, taking the high currents between the battery, inverter and eMotor. With light weight, reliability and rapid disassembly all factors in the cabling installation, the cable choice and the connector technology are critical and often unappreciated by the fans. I’ve recently purchased some Ex-F1 DC connectors\cables which give us some appreciation of the tech involved here. These are both Red Bull RB8 (2012) parts, taken from the DC (battery to inverter) bus. Rather than simply being big fat copper cables with two pin connectors, they are remarkably complex in their design.

Cable

Cable

Being DC cables, there are two cables, separated by a silicon divider, both shrouded with shielded layer and then encase in the trademark orange sleeving. Peeling away the sleeving and shielding the DC copper cable is printed with Hi-Flex 25-903, a quick google suggests this is Habia Hi-Flex cabling (Habia.com). Specifically made as a flexible power cable, designed for initially for Military and latterly EV use. The cable used here uses a 25 mm2 copper core and is rated at up to 250A. The resulting cable has a copper core dia of 7.3mm and an outer dia of just 9.5.mm. Its surprisingly flexible and light, at just 255 grammes per meter. Teams are known to run the minimum size cable to save weight, even to the point the were the cable runs hot and thermocouples are fitted to the cable\connector in testing to assess the thermal impact on the cables.

KERS DC Connector

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We have two connectors here; one I can confirm is the fitting that goes into the KERS Control Electronics (KCU or Inverter) on the right hand sidepod. The KCU is a Magnetti Marelli unit, this DC cable goes in to its outer face, then the three AC 3-phase cable emerge from the other (inner) side.
The DC cable bundle enters the connector, from where the smaller data cables emerge through a 3D printed boot. This boot being a two-part item held on with a cable tie. The joint is filled with a black resin to keep water and dirt out of the connection
The connector despite appearances, the connector is plastic, a pale brown colour suggesting the material could be ‘Peek’, a 3D printable product often used for electrical installations. The outer surface of the connector is then metalised, a process whereby a metal coating is applied to the material. At this stage I’m not sure if this actual connector is a race item or a R&D\mock up part. It certainly shows signs of use and has two full part numbers (RB8-KS-00719-02 – LT3-KS-00275).

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In use the connector bolts with a right handed-connection into the KCU with three 3mm bolts, a connection being made with both the two DC poles and also a 5-pin data connector. Inside the DC interface, the connection is sealed with an O-ring, one pole being marked A and the other B. Each of the DC connections is a female copper terminal which appears to be crimped to the copper cable. Fitting quite loosely inside the connector, I suspect these terminal would normally be sprung mounted to ensure a clean and firm connection with the male terminals on the KCU.
The panel that closes the DC terminals also houses a flange to mount the data connection, this is 5 pin military style connection, that mates with the KCU when fitting the DC connections. A separate cable emerges from the boot that appears to be grounded to the main connector body. These may be connector for the Battery Management System, or from sensors (thermal?) within the cable assembly itself.
Not wanting to cut the cable from the connector I can’t give an accurate weight of the connector, but it’s a few 100g’s and very light. If not a race part, I suspect the finished metal part would still be very light indeed.

Inline DC KERS Connector

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I don’t have an identification for the use of the second connector (part number RB8-KS-00361-02), it’s still a DC Bus connector and shares many of the features of the first connector. Again it has a metalised plastic body, a 3D printed plastic boot. But this time the connector is an inline type and sports two sets of 5-pin Data connections. One major variation to the KCU connector is the mounting method.

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This has two mounts to secure it to whatever is connects to. These are rubber damped anti-vibration mounts, so perhaps suggests this is for a powertrain, rather a chassis mounting.

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