Passenger car technology is facing many challenges, most of which are driven by the need to bring down the vehicle carbon footprint. One key strategy to achieve this goal is weight reduction as the vehicle mass directly influences fuel economy and thus CO_2 emissions. This is why the share of lightweight materials in the car keeps growing. Since the cable harness is one of the heaviest single components in a passenger car, it is no longer exempt from weight reduction measures. In Germany, for instance, the terminals that connect the starter battery to the vehicle electric network are usually made from solid aluminum (Al). The weight benefit of this material substitution is considerable because an Al conductor that carries the same current and voltage at the same resistance level like a copper cable (Cu) will only have half its weight. However, the use of Al in the car has been restricted so far, because unfortunately Al is not only a good lightweight conductor which costs around a third when compared to Cu. Al also has a most unwelcome material property that is particularly challenging in stranded conductors: Al tends to creep from 80℃ when it is exposed to mechanical load. This can effectively limit the durability of a conductor termination as the creep can impact the electrical characteristics of the contact points. Another challenge is posed by the potential difference between Cu (0.3 V) and Al (-1.69 V). In the presence of moisture at the immediate point of contact this will result in the dissolution of aluminum, the baser of the two metals. Finally, Al is a ductile metal which possesses only one third of the mechanical strength of Cu. In order to achieve the required degree of pull-out strength, which is typically specified by OEMs at between 60 and 90 N, this flexural sensitivity needs to be considered during dimensioning of the conductors.
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