Insulation for battery cables with DuPont™ Vamac® AEM

The Tesla Roadster is fitted with battery cables from Huber + Suhner, encased in

DuPont™ Vamac® ethylene acrylic elastomer (AEM) has been chosen by Huber + Suhner AG, Switzerland, a leading supplier of automotive cable systems, as insulation for battery cables supplied to Fiat, Ford, Jaguar, GM/Holden and Renault, and also as screened insulation cables for hybrid prototypes and the fully electric Tesla Roadster.

Vamac® AEM was specified primarily because of its excellent high temperature and fluids resistance in tough automotive operating environments from -40°C to +150°C, involving hot motor and gearbox oils, battery acid, salt water and cleaning solvents, and for its flexibility and abrasion resistance in confined spaces. In addition, the compatibility of Vamac® with fillers or flame retardants, and ease of cross-linking with electrons, were other important selection criteria.

Long-term service in battery cable insulation
Huber + Suhner uses Vamac® AEM as a component in a special compound formulation for its successful RADOX cable insulation and jacketing material. Since commercial introduction 5 years ago, the effectiveness of RADOX with Vamac® in a range of battery and power cables for automotive applications has clearly been demonstrated.

Heinz Oesch, Product Unit Manager for the Automotive Wire and Cable Division at Huber + Suhner AG, comments on cable requirements in today’s automotive applications, and explains why his company relies on Vamac® AEM to provide long-term service in battery cable insulation.

"The key function of a cable insulating material is resistance to high and low temperatures, plus engine oils and battery acids, coupled with good flexibility and the ability to absorb fillers and flame retardants. Cable flexibility is important because it allows better and easier installation around a small radius. Abrasion resistance is also essential since our cables are based on thin wall insulation to provide smaller overall diameters. This helps reduce weight and enables installation in very confined spaces."

"We chose Vamac® for its long-term heat and oil aging resistance in aggressive operating conditions, and its ability to absorb fillers and crosslink. RADOX compounds are treated with electrons to crosslink the polymer and further enhance their thermal, mechanical and fluid resisting properties."

The move to hybrids
RADOX battery cables made with Vamac® AEM have become standard equipment at Fiat, Ford, Jaguar, Renault, and the Holden Division of General Motors. In the transition to hybrid motor technology, Huber + Suhner are working closely with GM in the USA and selected European OEMs to supply screened battery cables for hybrid car prototypes, several of which are expected to go into serial production soon.

The company has also been selected for an assembly project for Tesla Motors Inc. to provide screened and non-screened battery cables with insulation made of Vamac® AEM for its groundbreaking Tesla Roadster — claimed to be the first production battery electric vehicle to travel more than 200 miles per charge, with zero tailpipe emissions. Huber + Suhner will soon supply cables for the Tesla Model S all electric family sedan as well.

Heinz Oesch sees a strong trend towards electric or hybrid cars due to the improved fuel consumption and low to zero emission possibilities these technologies offer. He believes the transition is being driven by high oil prices, environmental responsibility, tough new emissions regulations, and financial support from governments for such applications.

"Cables for hybrid and all electric vehicles need to be small and flexible, and resistant to the high temperatures generated by high voltage electric currents. Crosslinked RADOX insulation provides all those functions. In addition to our cable know-how, we also offer full cable assemblies including conductors and other parts."

"Vamac® offers the ideal properties for our niche applications in the high temperature range, and we expect this market segment to grow, especially through hybrid and electric car developments."

DuPont™ Vamac® AEM and DuPont™ Viton® Fluoroelastomers in wire and cable
Increasing demand for high performance, lightweight cables made of safe and environmentally friendly products is driving material suppliers and cable manufacturers to develop innovative solutions with improved properties
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DuPont Performance Elastomers offers its V Solution products — Vamac® ethylene acrylic elastomers and Viton® fluoroelastomers — for high quality, high performing cable jacketing and insulation. These next generation elastomers enable precise tailoring of cable compounds in hardness, filler level, and melt viscosity, coupled with smooth, corrosion-free processing.

Vamac® AEM has excellent heat and oil aging properties and does not emit toxic gases. It contributes high performance to halogen-free, flame retardant compounds and is widely specified for HFFR low smoke cabling, low voltage outer sheathing and jacketing. It also finds use in power, control and instrumentation cable in the automotive, rail, marine, mining and oil and gas industries.

Viton® fluoroelastomer delivers exceptional performance in low voltage insulation and jacketing, and meets growing demands from the automotive industry for high temperature and aggressive fuels resistance. Viton® can be crosslinked by irradiation and temperature.

RADOX® is a registered trademark of Huber + Suhner