DSM Engineering Plastics

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Going the distance with high-voltage charging

29 July 2019
  • Lennon ChuGlobal Market Development Manager

The automotive industry still has a few hurdles to overcome in the push to electric vehicles. The driving range of the vehicle is a big one, and so is the time it takes to recharge the battery. So far, driving range has been extended by increasing the battery size, or including high-efficiency AC/DC inverters and DC/DC converters, or high-efficiency AC motors. While these are all valid options, they add weight to the vehicle.

Ultimately, the most effective electric vehicles will be designed with miniaturized components that reduce weight and the space they consume in the vehicle. In the future, drivers will have the ability to drive long distances on one single charge, quickly recharge the batteries, plus, enjoy the driving experience along the way.

By increasing the voltage of the batteries, manufacturers can extend the range of the vehicle while also reducing charging time. This will give designers the freedom to design miniaturized components. However, high-voltage charging does place more stringent requirements on the materials used for connectors and insulating parts to keep the vehicle safe.

Most likely, future electric vehicles will feature much higher voltage charging systems to keep charging times convenient. While a battery charging at 400V might take 80 minutes to fully recharge, a battery charging at 800V would be 80% charged in 20 minutes. There is even further potential to reduce charging time—the goal being to reach a charging time similar to the time it currently takes to fuel a vehicle. Research on charging systems up to 1,500V is already being conducted in China, and in Europe infrastructure for 800V is being rolled out.

Mandatory materials requirement

High-voltage charging systems require materials that have a  higher Comparative Tracking Index (CTI) for connectors, cables and insulating materials. In the past, a high CTI was nice to have, but not mandatory. However, with high-voltage charging, it becomes a material requirement. 


Designers also need to consider creep distance, with pitch size and minimum wall thickness of the insulator material defined with no room for modification, along with additional sealing to protect the connector from environmental pollution like dust, moisture and sweat.

Insulation materials with a higher CTI reduce the risk of high voltage connector failures due to arcing and short circuits, despite ever-smaller creep distances. But most standard materials currently available for CTI are only rated up to 600V, and most CTI testing equipment only goes up to 600V. Yet, this did not stop DSM from developing ForTii and Akulon compounds with high CTI values.  

DSM is the only plastics manufacturer with materials in its portfolio that qualify for CTI above 600V. Our ForTii® TX1 grade has a UL 94 V-0 rating at 0.4mm and a CTI of 900V. ForTii T11 has a UL94 V-0 rating at 0.2mm and a CTI of 875V. Akulon® SG-KGS6/HV has a CTI of 700V. All these materials are phosphorous and halogen free. They are the only commercially available materials that demonstrate high CTI when creep distance is critical.

To learn more about ForTii and Akulon materials or to request test samples, contact us or visit plasticsfinder.com for additional information, including technical data sheets.

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