The Story Behind the EP Tender
By Bill Moore
Would you be interested in an electric car that can cross the country without stopping to recharge and, as a bonus, you don't have carry around that gasoline engine all the time? You just snap on a range-extender and way you go.
The concept's not entirely new, of course. AC Propulsion created just such a solution for their t-Zero back in the day. Now a Frenchman has given it a new twist: range extension-on-demand.
But first, let's get a bit of background, starting with the predecessor of the t-Zero.
General Motors engined the Chevrolet Volt with one overriding mandate: give it the ability to travel beyond the range of its electric battery pack when necessary. With the ground-breaking EV1, GM had learned a painful lesson, or so they had convinced themselves. Battery technology in the 1990s and into early 2000 wasn't up to the task of competing against the energy density of gasoline. it still isn't, in all honesty. While a dedicated minority of California drivers were happy with the EV1's 70-90 mile driving range, depending on the car's battery chemistry, the little two seater didn't catch on with the public at large.
Maybe it just wasn't given the chance to, it also has been argued, but regardless, when it came time to rekindle its electric car program in the face of upstart Tesla Motors and its little electric Roadster, the decision was made to give its next electric car a gasoline engine backup. The Chevy Volt 1.4 L 4-cylinder ICE-age power plant's job isn't to provide traction, but electric energy, spinning an 55 kW generator. Only under certain scenarios does the engine provide mechanical power. The car's 16kWh lithium-ion battery pack is large enough to propel the car between 25 and 50 miles without running the gas engine. Once the battery depletes sufficiently, the engine automatically powers up and the generator begins supplying power to the car's electric drive motor via the battery pack.
The arrangement provides nervous EV drivers with the level of confidence they need to mitigate the phenomenon called 'range anxiety.' Just like a conventional car, as long as their gas in the tank, the car will keep going.
However, integrating that engine and generator adds weight and complexity that a battery-only car like the Model S or LEAF doesn't have to deal with.
Taking their cue from the Chevy Volt, BMW decided to give future i3 customers an option. They could order the i3 with ICE-age range extender, one intended only to back-up the electric car's battery pack, giving the driver the ability to go up to 180 miles instead of the car's projected 90 miles. BMW engineers shoehorned a tiny motorcycle engine in the back of the car next to the electric drive motor. It added weight and another $4,000 to the already hefty $42,000US price tag for the battery-only version.
If we compare Nissan LEAF sales with those of the Chevy Volt, it appears the verdict is not yet in as to which approach makes the most sense to buyers: sales have been running pretty much neck-and-neck.
So, we decided to ask EV World readers their preference. Is the expense of having a range extender worth it to them?
According to early responses to our February 2014 ePoll, a majority of respondents so far appear to think that the added cost of a range extender - be it gasoline in the Volt and I3 or hydrogen fuel cell in the case of La Poste and FedEx delivery vehicles - is worth it to them.
Which brings us to one Jean-Baptiste Segard, the founder of the French startup, EP Tender . His big idea is offer EV drivers the ability to rent on-demand a small towable range extender.
In the video below, Segard explains to CleanTechnica's Zachary Shahan the workings of the EP Tender. For the non-nautically inclined, a 'tender' is a small launch that is often tied behind a larger vessel like a sailboat or mounted aboard a cruise ship or naval vessel. It provides ship-to-shore conveyance for passengers, crew and cargo. EP's Tender is a small tailer with an gasoline engine/generator mounted on it. You simply hook up the trailer and your electric car now can drive hundreds of more miles than on its battery pack alone.
With our apologies to both Segard and Shahan, we used EP Tender's own video to help illustrate the Frenchman's comments to the CleanTechnica director. We trust they won't mind our recompiling their two separate videos, which naturally complement each other.
The beauty of the EP Tender is that you use it only when you need it. Research over the years has demonstrated that 80% of the driving we do is less than 40 miles. Only on rare occasions do our trips exceed that. What Segard proposes is to station EP Tenders are convenient locations where you can pick it up, drive across country and then drop if off - U-Haul trailer/truck-like, at the other end. From Segard's comments in the video, the rental rate will be competitive, certainly a lot cheaper than the cost of buying such a trailer or even opting for the i3's little range extender option.
When you watch the video, it's obvious the Frenchman put a lot of thought into the device, especially introducing a nifty, retractible undercarriage system to make it easy to back-up with the tender attached.
However, as slick as the concept is, obstacles loom: the chief being carmaker buy-in. Renault got burned once already with Better Place and their swappable battery concept. I suspect they might not be too receptive to Segard's system, despite being a pretty good idea. BMW's already invested in its onboard range extender and Volvo has chosen to go the plug-in hybrid route. Maybe Volkswagen?
Unfortunately, Segard faces the classic 'chicken 'n egg' conundrum. He isn't going to build EP Tenders - or worse, find the money/investors - without carmaker buy-in and carmakers aren't going to adapt their vehicles unless they believe there is sufficient public interest to do so.
It would seem the logical pathway forward is to work with aftermarket suppliers who can retrofit existing cars with Segard's hitch system. There are lots of companies that already offer hitch installation services. The big challenge then would be safely taping into the EV's battery and charge control system. Several companies succeeded into doing that with the Prius before the introduction of the Volt. With a little carmaker cooperation, sharing code between the two systems would be much easier than hiring programmers to hack the system.
So technically, there are no show-stoppers here, just the usual public ignorance and industry apathy.
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