Towing Raises New Issues When EVs Are InvolvedBy (Display Name not set) February 10, 2011
By Robert E. Calem, Contributor
On a recent walk past the place tow truck drivers take impounded vehicles in New York City, I noticed one of Frito-Lay Co.'s shiny new electric delivery trucks - a Smith Newton. It had been taken off the street, apparently for a parking violation, and now was being reclaimed by a couple of uniformed Frito-Lay employees.
No surprise there.
But there was something very odd about the way the truck was being recovered - with another tow truck. So I asked why.
The answer was instructive: Towing this truck without time-consuming preparation work to disengage the electric motor could cause serious damage, and Frito-Lay, worried that the city's tow driver hadn't done that prep work, didn't want to drive it away and exacerbate any damage that might have been done by the initial tow.
Lesson: While they're a great solution for many who want a way to cut fuel and vehicle maintenance costs, battery-electric vehicles present unique challenges, beyond the obvious need to always have them within reach of a recharging station.
And it's not just fleet owners who should think about these challenges before buying electric.
Individuals purchasing a new electric car such as the Nissan Leaf and Ford Focus EV need to be aware as well.
Problems related to towing EVs - by city traffic enforcement agents and untrained rescue tow truck drivers, too - are bound to multiply as sales of these vehicles, personal and commercial, increase in coming years.
Fortunately, these concerns are less a problem with mass-market vehicles like the Leaf and Ford's Transit Connect EV small van, thanks to some key engineering differences that set them apart from a big truck such as the Smith Newton: front-wheel drive and a gearbox.
Spinning Wheels, Hot Metal
Unlike an ordinary vehicle or even a hybrid, explains Bryan Hansel, chief executive of Kansas City-based truck maker Smith Electric Vehicles U.S., a pure electric vehicle has no transmission connecting its motor to the driving wheels.
The Newton takes things a step farther and eliminates a "neutral" position in which the driven wheels are disengaged from the motor. So while a tow truck operator can throw a regular truck into neutral to easily disable its drivetrain before rolling it away, there is no neutral with a vehicle such as the Newton.
As a result, towing it from the front with its rear drive wheels rolling the entire distance to the pound will keep the electric motor spinning. Because the truck's power isn't on and its liquid cooling system active, friction from that spinning if the truck is towed for some distance could heat the motor to the point of destruction.
"It's purely just the fact that you're overheating a piece of metal and at some point you're going to cause some damage," said Hansel. Worst case with one of Smith's medium-duty trucks is that the electric motor can burn out and need to be replaced, at a cost of about $5,000.
"That's why we say to our customers, if you're going to tow it from the front, then you need to drop the driveshaft" - a process that can take a trained mechanic 20-30 minutes - "or tow it from the rear, so you're not spinning that motor, you're not creating that heat and there's no issue," Hansel said.
At office goods supplier Staples, another major operator of Smith Newton electric delivery trucks, fleet equipment manager Mike Payette says he is aware of the risks posed by city traffic agents, and hopes to avoid them altogether.
"They're not looking to spend a half-hour at the scene pulling a driveshaft down. They want to grab it and go," Payette said of city tow truck operators. "That's why I put warning decals on the front of the vehicle as well as on the gear shifter."
The decals say "Do Not Tow" - the trucks should be hauled on a flatbed instead - and Payette figures that if a tow driver ignores the warning and the truck is damaged, "we've got something to go back to the towing company or the city on and say we warned you...you're liable for it."
Of course, not all electric vehicles are engineered identically.
While the Nissan Leaf and Ford Transit Connect EV don't have transmissions either, they are front-wheel-drive vehicles, so towing them from the front with the rear wheels turning on the road - the most likely scenario when a vehicle is towed by a city traffic agent - won't result in damage, their makers say.
Additionally, both are equipped with a single ratio gearbox that allows them to be shifted into either a "Park" setting, which locks the driven wheels, or into "Neutral," to disconnect the electric motor from the driven wheels.
With the Ford Transit Connect Electric van in particular, "there are no differences in how you would tow this vehicle versus a stock gasoline-powered Transit Connect," said Jim Mancuso, vice president for current product engineering at Azure Dynamics Inc. of Oak Park, Mich., which builds the electric-drive version of the van under contract to Ford.
"The vehicle is designed to be transparent to the operator," he said. Neutral is selected with a normal-looking gear shifter, and tow truck operators would not need to take any additional steps beyond shifting the van into neutral before driving away with it, Mancuso added.
The Nissan Leaf is a bit less mainstream. Its shifter looks more like a computer joystick, and putting the drivetrain in Neutral requires turning on the ignition.
For that reason, the automaker recommends always hauling an immobilized Leaf on a flatbed truck, said Mark Perry, director of product planning at Nissan North America.
In bold type, the Leaf owners manual states, "Never tow with the front wheels on the ground or four wheels on the ground, forward or backward, as this may cause serious and expensive damage to the motor," Perry noted.
Additionally, he said, the Leaf's electric parking brake could be a source of concern in the case of an unexpected towing if it is engaged and preventing the rear wheels from spinning.
That's because disengaging it requires either powering on the car and using a switch in the cabin or, in an emergency, using a screwdriver to shut it off manually from inside the trunk. Either scenario requires the car's proximity key, which of course a city traffic agent would not possess.
When a tow is required and requested by the owner, none of this needs to be an issue; Nissan provides three years of flatbed hauling in the Leaf's roadside assistance service.
But if you drive a Leaf - or another EV with a similar powertrain design - and you park somewhere you shouldn't have and return to find the car gone, it would be best to check with the city tow yard to see how the car arrived before paying the fine and driving away.
Los Angeles-area public radio reporter Shirley Jahad posted this photo to her blog last spring of a Mitsubishi i-MiEV being loaded onto a flatbed truck after she ran out of juice during a test drive.
If you discover that it had been towed in, or can't find out how it was taken to the impound yard, your best bet would be to call the dealer and arrange to have your car taken there on a flatbed truck for a checkup before driving it away.
"If you did it for ten feet, there's one answer. If you did it for 100 miles there's probably another answer," Nissan's Perry said about the damage that could be done by towing a Leaf with its front wheels on the ground. "They can't really say what happens when," and that's why the owner's manual stipulates "never," he said.
Spokesmen for Mitsubishi and General Motors said their electric-drive cars - Mitsubishi's battery-electric i-MiEV and Chevrolet's extended-range Volt plug-in hybrid - also should only be towed with the front wheels off the ground and suggest that flat-bedding is the better way to go if you have a choice.
City Towing Minimizes Risk
For big trucks such the Smith Newton, there's one plus, said Smith's Hansel. Because the tow distance in a city is likely to be pretty short and the speeds low, the likelihood of severe heat damage to the spinning electric motor is very low.
Severe damage would require a tow at highway speeds over a long distance, he said.
Indeed, after inspecting the Smith truck I'd observed, Frito-Lay discovered that it hadn't been damaged by the tow.
Mike O'Connell, fleet director for Frito-Lay North America, said the company doesn't see intra-city towing as much of a risk.
Spokesmen for the various automakers agreed, with the caveat that, because most are front-wheel drive, they should only be towed - if a flatbed truck can't be had - with the front wheels off the ground.
Learning Curve Ahead
Still, there's a learning curve that city traffic agents and others who would tow electric vehicles will go through as EVs proliferate - as they will.
Early production units of the Transit Connect Electric are being delivered to corporate customers including AT&T right now, Mancuso said, and regular production versions of the electric van for general consumers are expected to begin arriving at Ford dealerships in early April. Ford also will begin selling a battery-electric version of the 2012 Focus later this year.
The first Leaf EV sold in the U.S. was delivered in December, commencing a still-slow rollout of the electric car to other buyers in Southern California, Arizona, Oregon, Tennessee and Washington. Deliveries in Hawaii and Texas are expected to start early this year with nationwide sales to begin next year. GM's been delivering Volts at a pretty rapid clip since late November.
Over the next couple of years, in North America and elsewhere, other automakers planning to sell mass-market-oriented EVs include BMW, Mercedes-Benz, Mitsubishi, Tesla and Think.
To date, Smith has delivered 55 Newton trucks to Frito-Lay and 53 to Staples, Inc., the office supplies retailer. By mid-summer, Frito-Lay will expand its fleet to 176 of the electric trucks, and Staples plans to have to more than 100 by year's end. In addition, other companies committed to buying Smith electric trucks include Coca-Cola Co., Pacific Gas and Electric Co., and AT&T Corp.
So while some issues exist today in towing EVs, Hansel said, a decade from now they'll be such a familiar sight on the streets that removing one from a snow path or expired parking meter will be no different than towing any other vehicle.