What Is a Heated Seat Belt?
By warming occupants instead of the air, heated seat belts could help extend EV battery life in cold weather.
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Heated seats and steering wheels have been available in cars, trucks, and other vehicles for years. They use heating coils and wiring to give warmth on cold days. Now the global technology company ZF hopes to extend that concept to seat belts, and the company’s vision for what might come to be known as “heat belts” goes beyond merely keeping drivers cozy.
If cold weather is unpleasant for drivers, it’s downright brutal for electric vehicles (EVs). By their nature, battery-powered devices — including EVs — become sluggish and lose their charge quickly as the temperature drops. Depending on cold conditions, there can be anywhere from a 30% to 41% reduction in an EV's range.
This is where heated seat belts could prove helpful by reducing the demands placed on EV batteries by cabin-heating HVAC systems.
Waste Heat Is So Yesterday
For decades, passengers have relied on a gas engine’s “waste heat” — engine heat drawn inside the cabin by a fan — to warm up the air. That doesn’t work in EVs. Without an internal combustion engine, an EV must rely on a heating device that draws power from the car’s battery. This can further shorten driving range that’s already compromised by the cold weather.
ZF’s Martina Rausch and her seat belt development team have been working on a solution to this problem since 2020. The team designed heated seat belts that work in conjunction with heated seats to warm occupants directly, greatly reducing the need to heat the entire cabin.
“It’s a concept very similar to an electric blanket,” Rausch said. While current automotive HVAC systems warm the cabin air, the heated seats and belts heat only what comes in contact with them, and they can do it much faster and more efficiently.
For best results, ZF recommends that passengers take off their thick winter jackets so the heated seat belts lie closer to their bodies, which both increases heat transfer and could potentially improve crash safety.
How ZF’s Heated Seat Belts Are Made
To create its heated seat belts, ZF weaves small heating conductor wires into the webbing just like regular thread. The result is a seat belt that looks and functions very much like a traditional seat belt.
“There is no difference in terms of operation when compared to a conventional belt,” Rausch said via email. “The heated seat belt is in no way inferior to its conventional counterparts in terms of crash behavior.”
Because heated seat belts are no thicker than conventional seat belts, ZF says they’re no more challenging for carmakers to install, making them well-suited to mass production.
Are More Heated Seat Belts Coming Soon?
As EVs become mainstream, such range-enhancing innovations will become increasingly important, especially in states that see more extreme temperatures.
Rausch said she expects heated seat belts to start showing up in cars around 2025, although the company has not yet received any firm commitments from carmakers. If she’s right, EV drivers can look forward to both cozier and longer winter rides: ZF projects its battery-saving seat belts could boost cold-weather range by as much as 15%.
