• Apr 12th 2011 at 1:57PM
  • 22
Trexa Enertube chassis prototype – Click above for high-res image gallery

Trexa has finally raised the blinds over at their workshop and revealed that its skateboard platform concept has turned tubular. Totally! The light of day glinting off the production chassis reveals a structure with all the unnecessary bits removed and the remainders incorporated into a shiny torque tube connected to a set of wheels via a pushrod suspension set-up.

The changes leave its modular adaptability intact and perhaps quite improved. The 7 kWh lithium phosphate battery pack of this initial 96-inch long example can be doubled by changing the diameter of the Enertube from from nine inches to twelve. As well, the length can be stretched and the system is said to be capable of supporting everything from a golf cart to a class 8 truck with a 100 kWh battery.

Trexa has teamed up with a specialty vehicles manufacturer for commercialization and customers will receive the first evaluation platforms in May. Additionally, the company has partnered with Carnegie Mellon Robotics to develop "advanced functionality platforms for government and agricultural applications." It's also generated interest from a major auto racing league with an eye towards an all-electric series.

The smaller outfits haven't been forgotten either and CEO Seth Seaberg credits the "re-emergence of electric drive" to grassroots efforts and hopes to offer products for independent, kit and custom car builders in the future. Check out the gallery below then hit the jump for all the details in the official press release.

[Source: Trexa]
Show full PR text


Los Angeles, April 11, 2011--Trexa LLC, the electric drive vehicle platform manufacturer,
announced today the filing of a U.S. patent application for its Enertube™ tubular energy
storage technology in connection with the unveiling of the TREXA® production
prototype. The first TREXA vehicle platforms will be shipped to customers for evaluation
in May.

While the TREXA concept vehicle platform introduced early last year featured an iconic "skateboard" form, the production platform is pure function. Driving this design is the Enertube, which is an energy storage system that doubles as the main load-bearing structure for a variety of vehicles. This proven concept of using a so-called "torque tube" or "backbone" chassis dates to the 1960ʼs. Differentiating the TREXA platform are interchangeable parts on all four suspension corners, which keeps parts count low, makes platform integration fast, and makes maintenance easy for end-users. All the major mechanical subsystems, including the transaxle, are manufactured by TREXA in the USA with support from Tier 1 automotive suppliers.

Vehicle applications mount to the TREXA vehicle platform by way of several hard points located on the front and rear suspension subframes. The subframes are attached to the Enertube. A pushrod suspension and 2WD or dual-motor 4WD options enables broad adjustability for both on and off-road applications. After a vehicle application is mated to
these subframes, the Enertube is able to be removed for maintenance or future upgrade of the modular battery. The current generation Enertube utilizes thermally stable lithium iron phosphate cells and a proprietary third-generation BMS (battery management system), which have been extensively tested and proven since the TREXA engineering team developed EDrive, the first commercially demonstrated li-ion PHEV, in 2006.

Central to the TREXA patent application is scalability of the battery system. The nine inch diameter Enertube utilized on the 96" wheelbase prototype contains 7 kWh of energy storage capacity, suitable as a platform for a local use plug-in vehicle or small series PHEV. However, small increases in tube diameter dramatically increase energy storage capacity. For example, an increase in diameter from nine inches to twelve yields a twofold increase in energy capacity. TREXA plans to offer Enertube-based platforms in a range of diameters and lengths, representing energy storage capacities to over 100 kWh. As a result, TREXA platforms could be the basis for electric drive vehicles ranging from golf carts to Class 8 trucks.

TREXA has formed an alliance with a large publicly-traded specialty vehicle manufacturer to commercialize the platform and Enertube technology. TREXA is also exploring electric racing in connection with a major auto racing league. In addition, the company is working with the Carnegie Mellon Robotics Institute to develop advanced functionality platforms for government and agricultural applications. The company plans to make specific announcements about its developer and supplier relationships in the coming months.

"TREXA is both a learning and a teaching company," said CEO Seth Seaberg. "We have spent a great deal of time in the past few years understanding what our developers need so we can educate them about, and provide them with, the appropriate and scalable battery technology. The Enertube is the culmination of that considerable effort."

Although initially it will work with established vehicle manufacturers and automotive R&D divisions, TREXA does have future plans to offer systems to independent, kit and custom car builders. "The DIY market has incredible potential, and there is no question that the re-emergence of electric drive is a result of grassroots efforts," said Seaberg. "So we are exploring how and when we might offer platforms, development guidelines, and support to the general public."

TREXA is funded in part by Crunch Energy LLC, a firm dedicated to developing innovative new technologies that help the world use less energy. TREXA expects to close its next round of funding this summer.

For more information, visit the companyʼs web site, www.trexa.com, email info@trexa.com.

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    • 1 Second Ago
      • 8 Months Ago
      "The 7 kWh lithium phosphate battery pack of this initial 96-inch long example can be doubled by changing the diameter of the Enertube from from nine inches to twelve."

      96 in x pi x 12^2 / 4 = 10862 cubic inches = 178 liters

      According to GM, thats the volume of a hydrogen needed to give a family car a reliable 300 mile range:

        • 8 Months Ago
        Well, then GM better hurry it up with the HFC (hydrogen fuel cells)! They've been "working" on HFC technology for over 40 years now without a single production vehicle...
        • 8 Months Ago
        Nice link thx. Quite a few apps already....like my 65 VW bug, Lotus etc
      • 8 Months Ago
      better than their first attempts. somewhat interesting approach. isolated speaking the tube storage is clever although limiting the type of cell that can be used.
      ultimately I don't think it will be a successful design though because you still need the floor, you still need the side impact strength, you still need a place to mount the rest of the body. so it lacks holistic thinking.
      I'd propose a composite sandwich floor for both floor and basic stiffness and add some walls so it forms a tub. a sandwich plate is a naturally stiff structure and is both aerodynamic on the underside and ideal for interior arrangement.

      I would also aim for much lighter wheels because of lower target vehicle weight.
      but why would they listen to me..
      they'll do their 3rd unsuccessful design and eventually run out of money..
      I wonder how they keep funding it.
        • 8 Months Ago
        For once, Dan, I agree with you. That tube is interesting, but not entirely practical given the battery space. Side impact isn't a super big deal. Plenty of cars are designed this way with the body stiffened against side impacts. I bet if they made that tube twice as wide, but flattened as you suggested, it would provide plenty of stiffness and room for a battery that is at least the beginning of useful. On the other hand, if you had the right, very light battery chemistry, you could use the storage of the battery in the tube as your reserve. Build your chassis with flat, prismatic batteries along the floor. 7 kWh would make for a nice reserve, much the way many gasoline powered vehicles still have 20 or 30 miles of range once they show E on the fuel gauge.
        • 8 Months Ago
        You don't need all that stuff.

        Just ask Major Kong.

        • 8 Months Ago
        I wouldn't place the batteries in the floor but on the floor in blocks either in front of the cabin or behind.
        they would be exposed to damage from below and thermally exposed if driving in severe cold. it's also a problematic weight to have as a flat plate vibration wise. it's like a bridge span instead of a more stable placement over the wheels axles.
      • 4 Years Ago
      It seems that there is not cooling for the batteries? Is that realistic?
        • 8 Months Ago
        Large format cylindrical cells from what mfg??? Are they A123. The chemistry would be right for good tolerance to temperature.

        Nifty concept without a doubt. It would make a nice little hot rod!!
      • 4 Years Ago
      "The DIY market has incredible potential, and there is no question that the re-emergence of electric drive is a result of grassroots efforts," said Seaberg. "So we are exploring how and when we might offer platforms, development guidelines, and support to the general public."

      Yeah, buddy.... that's what I"m talking about.

      My snap-on roll cab anxiously awaits.
      • 8 Months Ago
      The original skateboard concept was much much better. 7kWh isn't very useful, and that motor/controller combo is limited to 120V and 650 amps.
      • 4 Years Ago
      It would be nice to see a big automaker assembly-line these to bring the costs down. They need to be able to get it down to ~$8,000 to sell a lot of them ($15,000 car). It will be a challenge though.

      They could come up with basic models or have 3rd party companies design different models to bolt on.

      It would be like computer programming. The big components have standard ways that they interface with each other, but their design can be very different.
        • 8 Months Ago
        $15k car?, thats an econobox.. this will be used for $50k sportcars and such.. the motor and inverter alone may cost more than $8k
      • 4 Years Ago
      Very Cool!
        • 8 Months Ago
        Very interesting. Take a look at the second image... anyone ever see "The Rock"? Is Nick Cage in on this?
        • 8 Months Ago
        looked at the pic...

        Wow, who would have thought that VX would make a great electrolyte for Li batteries! LOL
      • 8 Months Ago
      The last several decades of automotive evolution has brought unibody construction to nearly every class of automobile, including trucks, and has just retired the last major body on frame car, the Crown Victoria. Now we are ushering in the future of the electric vehicles with a modular body bolted to a torque tube? Am I the only one who sees this as a back step?
        • 8 Months Ago
        @ Bip-D-BO

        Nope, you're not crazy, this design is very old and has so many impractical defects that it's just a complete waste of time and money.

        The market in the future for 'kit cars' will be very limited. The concept of a 7kw tubular spine just being extended or enlarged to accommodated more batteries is fraught with practical difficulties. It doesn't need a great engineer to explain why the major companies have shown no interest in attempting to attach a body to this impractical design. Anyone who has actually built a functioning EV would not be impressed by this latest effort, of 'back to the future'.

        Oh and the cost of this bizarre project should kill off any hope of recouping losses.

        But, who knows ? DF has already completley redesigned it!
        • 8 Months Ago
        I don't see it as a step back. Using one platform for everything from golf carts to trucks would reduce costs considerably. Assuming their claims are accurate. Weight could be a major issue however.
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