Automotive

Thor pushes forward with self-propelled electric camping trailer

Thor pushes forward with self-...
An electric-assist trailer concept, the 2018 Dethleffs E.Home Coco featured an 80-kWh lithium battery and solar panels
The 2018 Dethleffs E.Home Coco featured an 80-kWh lithium battery and solar panels
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The eTrailer system is an electric drive system that could underpin a variety of self-powered caravans; here, an early prototype is paired with the Dethleffs Coco
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The eTrailer system is an electric drive system that could underpin a variety of self-powered caravans; here, an early prototype is paired with the Dethleffs Coco
Dethleffs reveals the E.Home Coco on the opening day of the 2018 Düsseldorf Caravan Salon
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Dethleffs reveals the E.Home Coco on the opening day of the 2018 Düsseldorf Caravan Salon
The E.Home Coco uses a pair of electric motors on its single axle
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The E.Home Coco uses a pair of electric motors on its single axle
An electric-assist trailer concept, the 2018 Dethleffs E.Home Coco featured an 80-kWh lithium battery and solar panels
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The 2018 Dethleffs E.Home Coco featured an 80-kWh lithium battery and solar panels
The E.Home Coco prototype allowed the Audi E-tron Sportback to make use of its full range while towing the trailer across the Alps
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The E.Home Coco prototype allowed the Audi E-tron Sportback to make use of its full range while towing the trailer across the Alps
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The groundbreaking Dethleffs E.Home Coco camping trailer has taken another big step toward reality. Parent company Thor Industries and German automotive supplier ZF Friedrichshafen are teaming up to clear the hurdles that stand in the way of a viable production trailer that uses electric motive power to move its own weight. The self-propelled trailer promises to be a critical tool for eliminating the efficiency and range reductions a trailer makes on its tow vehicle, something that will be especially helpful in the electric vehicle age.

Before the RV world sees the realization of self-driving motorhomes, it seems it might welcome self-driving trailers. Germany's Dethleffs showed the first fruits of this work in 2018, when it followed up the original solar-slathered E.Home motorhome with the E.Home Coco electric trailer. That self-driving trailer, and Dethleffs' leadership in eco-friendly camper design in general, played into Thor Industries' decision to acquire Dethleffs' European parent Erwin Hymer Group (EHG) in 2019 to become the world's largest RV manufacturer.

"When we acquired EHG in 2019, there were many synergies which made the acquisition important to Thor," explained Thor's COO Todd Woelfer in a recent announcement. "From our perspective, EHG was the global leader in electrification innovation in the RV space. They had initiated this [E.Home Coco] project with ZF in 2018, before we acquired the company."

Since that acquisition, Thor brands have continued to work together with ZF to develop the electric-propelled trailer technology, which Thor calls the eTrailer System. The idea is to use an integrated electric motor drive to empower the trailer to move its own weight, dropping the effective tow weight on the hitch to zero. The most critical part of the eTrailer design is the electronic sensor and control system that keeps the trailer operating at the same speed as the tow vehicle, cutting the tow load without negatively affecting the safety, ride or handling.

The E.Home Coco uses a pair of electric motors on its single axle
The E.Home Coco uses a pair of electric motors on its single axle

Late last month, Thor announced the latest step in the push for electric trailer technology: the execution of a binding memorandum of understanding with ZF. The agreement lays out the two companies' plans to jointly develop the proprietary eTrailer high-voltage electric drive system for towable RVs.

"Our relationship with ZF gives Thor the exclusive rights to this technology in the RV space for a certain period and perpetual rights in key aspects of the intellectual property supporting the development," said Woelfer.

In July 2021, Dethleffs and ZF put the E.Home Coco to a major real-world test behind the Audi e-tron Sportback on a vacation-style journey they dubbed the Alps Challenge. Starting off with nearly-full Audi (96.4 percent) and eTrailer (99 percent) batteries, the team towed the E.Home Coco 240 miles (386 km) from Dethleffs' HQ in Isny, Germany to Lake Garda, Italy.

The E.Home Coco prototype allowed the Audi E-tron Sportback to make use of its full range while towing the trailer across the Alps
The E.Home Coco prototype allowed the Audi E-tron Sportback to make use of its full range while towing the trailer across the Alps

Much more than a basic autobahn sprint, the trip also involved climbing and descending through the Alps, including navigating the twists and turns of the Fern Pass Road in Tyrol, Austria. The team completed the journey on a single charge, consuming 82 kWh from Audi's 95-kWh battery and 74 kWh from the E.Home Coco's 80-kWh battery, factoring in the creation of a combined 17 kWh from regeneration.

Dethleffs says that the e-tron Sportback it used for the test had a 244-mile (393-km) WLTP estimated range, but even using currently advertised 281-mile (452-km) WLTP or 218-mile (351-km) EPA figures, the eTrailer test was a success. The e-tron Sportback with E.Home Coco drove to within 41 miles (66 km) of its maximum estimated range, and 22 miles (35 km) farther than its EPA-estimated range, without even using its entire battery capacity. In other words, the eTrailer motor system effectively negated the deleterious effect the trailer would have otherwise had on range, allowing the e-tron Sportback to complete roughly the same mileage it would have without a trailer.

As the Alps Challenge demonstrated, the eTrailer system could prove a boon, particularly for electric tow vehicles, which have been estimated and shown to lose up to half of their battery range when towing loads. Electric vehicles would be able to complete trips without constantly having to stop to charge or risking running out of battery power.

The eTrailer system is an electric drive system that could underpin a variety of self-powered caravans; here, an early prototype is paired with the Dethleffs Coco
The eTrailer system is an electric drive system that could underpin a variety of self-powered caravans; here, an early prototype is paired with the Dethleffs Coco

The eTrailer could also help other types of vehicles, including ICEs and hybrids, improve overall efficiency and decrease fuel consumption when towing.

Before any of that happens for actual RVers, though, Thor and ZF have some work left to do. Among their next steps will be showing the latest eTrailer concept at this year's Florida RV SuperShow in Tampa, where they will also highlight an electric vehicle concept that incorporates range-extender technology. The Florida SuperShow kicks off on Wednesday, January 19.

Source: Thor Industries

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8 comments
8 comments
Spud Murphy
Improving the aerodynamics of the trailer might help as well, it isn't the greatest design for reducing air resistance.
minivini
I have a few questions regarding torque/weight shift during highway acceleration. Most of us know what happens when the tongue weight becomes too light. On forward acceleration, torque would tend to push the forward weight upwards. I’m sure this has been well thought out, though.
Meanwhile, the concept is truly exceptional. The ability to pull a small to mid-size camper with most vehicle is a potential game changer. Imagine the possibility of adding a retrofitted “assist” drive to a camper to reduce the pull load to an existing camper! Our 3000lb caravan could be towed as if it was a 1000lb camper!
DaveWesely
This makes a lot of sense, except for the intermittent usage. The trailer could be used for electric home/grid balancing, either parked in the driveway or in an RV storage lot. Or they could design it with removable batteries that you rent. Without that, the trailer would be unnecessarily expensive.
Casey Shafer
Why the expense and the weight of the motors...just use the batteries in the trailer to power the tow vehicle
Mitch Berger
The Bowlus road chief price point would be a good starting point for this technology. Plus the Bowlus has a very low coefficient of drag. Would be great to see Forest River, Thor and Lance apply some aerodynamics to their rectangle boxes. The euros have us beat big time in this department.
ljaques
Outstanding concept...for those who can afford it. (It will likely be the equivalent of buying a Tesla model S to tow behind a Tesla model 3.) I wonder how soon mountainous areas will have fast-charging stations. The push-pull trailer coupling should have been interesting to design. Love their graphics.
vince
Every trailer, RV, etc should be electrified. Tesla is making a big mistake not moving into trailers as well as Semi's because that's the way to get their Semi's to 1500 miles range. By putting a mW battery in a trailer and powering it the Semi truck doesn't even have to be as powerful so they can design the tractor for efficiency when making the trailers do most of the work. This also is advantageous for trailers with coolers instead of having a noisy polluting diesel keeping things cool a mW of batteries will do the job more efficiency and much quieter and pollution free. Tesla should get smart and make their Semi trucks a tandem purchase--tractor plus trailor.
vince
In addition to allowing greater range they also boost the safety by a huge amount. A properly powered trailer can make jack knifes a thing of the past with smart electronics to even reverse the trailers wheel direction in order to 'pull' the tractor into a straight line. What causes jack knifes is that the tractor is 'stopping' faster than the trailer and so the trailer 'pushes' the tractor like a cop trying to stop a bank robber by hitting the rear of the car and causes it to churn around. Having driven Semi's for 5 years for Sears Roebucks I know what I'm talking about. This additional safety will work wonders in icy and snowing conditions when jack knifes are common when going downhill and a wind behind you and an icy road. The wind pushes the trailer while the tractor is trying to brake or slow down and viola you get a jack knife.