Towing can have a big impact on EV range, so Ford is mulling adding batteries to trailers to help compensate.

A Ford patent application published by the United States Patent and Trademark Office (USPTO) on August 3, and originally filed Feb. 1, 2022, details the use of bidirectional charging to connect an EV and a battery-equipped trailer, allowing energy to flow between them.

Ford trailer bidirectional charging patent imageFord trailer bidirectional charging patent image

The system would prioritize keeping the towing EV’s battery pack charged, drawing power battery packs in one or more trailers linked to together in a “daisy-chain configuration,” according to the application. The trailers could also be used to charge their own cargo. In the application, Ford suggests that trailers could be equipped with chargers for things like electric jet skis, motorcycles, ATVs, or dirt bikes.

Illustrations show a pickup truck with a distinctive cab-forward design that seems to be popping up in a lot of Ford patent filings. The automaker plans a high-volume electric full-size pickup as a follow-up to the F-150 Lightning in 2025, but the patent filing notes that trailer charging could be used in other vehicles, including SUVs like a three-row model with 350 miles of range also scheduled to launch in 2025.

Ford Gen 2 electric SUV after efficiency improvementsFord Gen 2 electric SUV after efficiency improvements

Using a trailer to extend EV range is not a new idea. The Boulder travel trailer from Colorado Teardrops has a 75-kwh battery pack that can be used to charge a tow vehicle while stationary. Airstream showed an eStream concept in 2022 incorporating a system that adds electric motors to a trailer to help take some of the load off the tow vehicle. That system, with a different trailer, managed to get 240 miles of real-world range out of an Audi E-Tron Sportback EPA-rated at 218 miles.

General Motors has filed a patent application for an alternative system that adds a self-propelled tow-assist device between the tow vehicle and trailer. This would provide supplementary propulsion to help move a trailer but, like Ford’s trailer battery, it’s still just a patent filing.

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