Wired: We plug in our Toyota Prius hybrid

After a five-month wait, we finally got our Toyota Prius converted into a Plug-in Hybrid Electric Vehicle. PHEVs are considered to be the next step beyond standard hybrids and perhaps an interim step on the way to pure electric vehicles. Our Prius plug-in will be among the many green machines at Friday’s invitation-only Future of the Car event at our Auto Test Center in Connecticut. (Follow the event on Twitter and here on the Cars blog, with coverage continuing next week.)

Getting plugged in
Several conversion kits are available for the Prius. We chose the HiMotion/A123 module. Having impressed us at an industry conference, this seemed like the most mature technology available. The module is installed at seven locations nationwide. It was pricey, though, and cost us $10,875 (on top of the price of the 2008 Prius Touring — $24,803).

This conversion entails installing a lithium-ion battery pack to augment the Prius’s existing nickel-metal hydride (NiMH) battery. That adds 187 pounds to the rear cargo area. An outlet for charging was cut into the rear bumper. The new battery sits in the spare tire well, which now moves the spare onto a secured tray on top of it. All in all, this reduces luggage space.

We’re told that the Li-Ion battery can supply enough juice to propel the Prius on electric power longer distances and up to higher speeds. Battery supplier A123 claims a 35-40 mile electric-only range from full charge to depletion. Recharging is done by plugging the car into a regular 110-volt household outlet and takes about 5.5 hours to fully charge. A spokesperson from A123, as well as other PHEV advocates, claims that the converted Prius can yield more than 100 mpg. However, drawing such conclusion is neither simple nor straightforward. These claims stem from testing on a dynamometer. Plus, this figure doesn’t take into account the amount of electrical energy that goes in to moving the vehicle. We intend to run it through our regimented on-road fuel economy tests and report the findings online and in Consumer Reports magazine.   

For the purpose of testing this kit, we’ve installed a dedicated outlet with an energy monitor. This way we can see the amount of electricity in kilowatt hours (kWh) that’s going into propelling the car on electricity only. We haven’t yet hooked the car up to our fuel-measuring devices.

In a pure urban setting, our Prius runs on electric power more of the time and reaches higher speeds. We’ve teased the car up to 43 mph on electric drive on a level road. Even with the conversion, the engine kicks in every time the car climbs even a slight grade or when the driver tips into the throttle beyond a gentle prod. The energy monitor in the dash shows the state of charge (SOC) of the Li-Ion in blue. It changes to purple as the battery is close to depletion. The Li-Ion doesn’t get any regeneration from coasting or braking as does the stock NiMH battery.

At this point, our plug-in conversion is meant to give a glimpse of an emerging technology, rather than present a viable alternative to a current car. Stay tuned for in-depth testing.

—Gabe Shenhar 

Discuss hybrids in the forums.

Comments

[Ken Grubb]

Way coolness. I'm oh so green, with envy.

[felixkramer]

I'm glad CR finally gets to try out having a converted PHEV. (I'm the world's first non-technical consumer owner of a plug-in hybrid -- as the founder of the California Cars Initiative, I got mine in April 2006. Since then, a few times I've gotten over 100MG of gasoline (plus a penny a mile or so for electricity) for entire tankful.) You can see where over a hundred PHEV conversions are on our website.

It's important to understand exactly what you're getting and the performance you can expect. The Hymotion website makes very clear that the 5kWh battery pack provides "Up to 100 mpg for 30-40 miles within electrically assisted driving range" http://www.a123systems.com/hymotion/products/N5_range_extender -- that's different than what you understoodd as "a 35-40 mile electric-only range." Because it's a conversion, at medium and highways speeds, the engine comes on, and perhaps 50% of the energy comes from electricity -- that's when you can get 100+MPG of gasoline. At low speeds (under 35MPH), the car can run electric only for perhaps 15-20 miles.

In Toyota's handful of conversions of its own product, the company tweaked the software to allow electric-only driving up to 54MPH -- making the obvious point that they can do a better job with their own product. (So be merciful in reviewing an admittedly compromised aftermarket conversion, which has been crash-tested so it's safe but doesn't have optimized performance.

Once Toyota decides to sell PHEVs, we'll all benefit. Right now, all the company promises is hundreds or more vehicles for fleet evaluation sometime in 2009 (under pressure from advocates and perhaps watching the timetable for the GM Volt, Toyota advanced that date from 2010.

-- Felix Kramer, Founder, CalCars.org

[Gillis Lang, Zero X owner]

It's been my personal experience that with each different electric vehicle configuration it becomes harder to communicate comparisons to the ever diminishing number of folks who only have used pure gasoline personal transportation. It's easy to cherry pick analytic results on different electric drive and storage system configurations and present them in strange ways that just confuses consumers, especially those consumers with no or little background in the product being described. I hope that Consumer Reports is very, very careful in their process of using, analyzing and especially writing about their new converted plug in Prius and does not fall into the most common 200 or so logical fallacies found repeated ad nausea so often on blogs and in the national media. Ultimately, the easiest thing is for consumers, once enough of a large ticket item are manufactured, to rent one at least twice (two different kinds if possible), for at least a week each and form their own opinions, misconceptions and personal preferences based on actual experience with real products. Before that, I'll be watching to see if I think that the information that Consumer Reports provides is a reasonable substitute for direct consumer experience for a plug in hybrid vehicle. Based on Felix Cramer's comments, I'm concerned about Consumer's Reports lack of experience, expertise and ability to report knowledgeably on plug in hybrid vehicles, although it may be the best available independent knowledge within their budget.

Thanks to major manufacturers dragging their feet and the media and blogs supplying constant streams of FUD and negative misinformation, electric drive personal standard configuration vehicles appear to be one the few areas where small manufacturers and actual consumers appear to know more than the so-called experts. It's pretty much all better than you think, would be my guess, but it definitely is different from a pure gasser or a non plug-in hybrid and all electric is definitely very different from an electric assisted gas or gas assisted electric drive (I've driven all those configurations).

From my own personal experience as a full electric drive vehicle owner, when I tried to understand my new full electric vehicle from a perspective as a non-plug in gasoline powered vehicle owner, I just confused myself. My respectful suggestion as an owner of a full electric vehicle, my daily driver (26 mile commute), is to buy an all electric drive vehicle, use it and be prepared to learn quickly (it's exciting) and to live with new (pretty much all better) ways. From that cognitive place, you can then back into understanding a plug in hybrid much more easily, I think. I suppose a plug in gas hybrid does make some sense as training wheels, not for a technology transition (the current power pack and electric drive technology is ready and has been economically viable for owners now for years and years), but for new to plug in electric owners to think and interact with their vehicles in new, improved ways and especially for OEM (original equipment manufacturers) marketing staffs to wrap their heads around a new world, have their new vehicle relationships become second nature, and figure out how to communicate their new understandings. Imagine how hard it was to market beer at first - acting drunk could hardly have done it, but getting the consumer a little buzzed (thanks to a real world sample) might.

My 100% electric drive lithium ion power pack vehicle (100% wind powered at low cost (less than the coal costs in some states), thanks to a wind power subscription plan offered from my local power utility) has exceeded every one of my expectations and exceeded every single one of the manufacturer's claims (how often can a consumer say that?). My mpge (equivalent) based on energy content or cost is shockingly high, the up front costs are less than the closest gas powered equivalent, the operating and maintenance costs are far less for electric drive and the performance is superior (an understatement).

Most folks, once the feel the torque and acceleration of primary electric drive vehicles in general, won't be turning back any time soon to something that puts much of its power into bellowing and clanking loudly while it balks, then sluggishly moves slowly, the relative characteristics of primary power from gasoline engines. Of course, you won't get a full sense of that in your parallel hybrid Prius plug in conversion (my electric drive vehicle has more electric power and weighs less), but you may get some of the fuel savings. Before folks jump on that one, remind me again when the payback happens on leather seats and unnecessary, random bits of heavy chrome?

My economic payback comes in sheer bliss every time I use my (wind powered) throttle and every time I pass a gasoline station and don't have to stop.

[Cale]

That's a lot of money for batteries. The $10,875 premium works our to 3,107 gallons of gas (@$3.50 gallon). That's a 5 year payback period compared to a vehicle that gets 20 mpg overall and is driven 12k miles annually. After 5 years, the Li-ion batteries will have 1/2 their capacity to hold a charge. Glad you guys are doing the experiment and not me!

[John Maben]

What are the odds? We just had a Hymotion conversion installed in our '04 Prius with 100k miles on Sep. 26 '08. We also intend on measuring every watt and gallon that goes in and mile down the road.

John Maben
Department of Environmental Sciences
University of Virginia

[Logician Bean Counter]

@ Cale,

Remind me again when the payback is on leather seats, sunroofs or cars in general? Oh, never? 5 years sounds way sooner than never to me.

One logical fallacy down, hopefully not another 199 to go.

[shaker]

Reply To: "Gillis Lang, Zero X owner":

Your long commentary is intriguing, yet vague at the same time.

A quick Google search reveals the "Zero X" as an electric motocross-style cycle -- is this what you drive?

If so, it's quite a machine, but a far cry from an enclosed, multi-passenger vehicle.

[Chris]

I am presently driving one of these cars and I get an average of 60 to 70 mpg. I can and have gotten over 160 mpg on short trips where its all electric which is--- less than 40 mph and less than 10 -15 miles. I can drive my kids to school soccer and such for about $1.00 The battery takes about a dollar to recharge and its equal to a gallon of gas. I love it and if you are going to work and its less than 25 miles one way and you can plug it in like I can at work then your commute is almost free.

[Erik KlnAir4U]

When you do a cost-analysis, make sure that you consider two major factors:
1. Gas will not be $1.50/gal in 10 years. Further, it will not inflate at the normal inflation rate. It will increase in cost exponentially. Include this in your calculations.

2. Some dollar value needs to be somehow attributed to pollution, climate change and global warming. Incorporate this factor in your analysis, please.

~ Erik
KlnAir4U

[tbrosz]

Including the energy used to recharge the batteries as part of a mileage calcuation sounds good at first glance, but it assumes there is no distinction between electricity and petroleum. This isn't true. Electricity can be generated by nuclear, solar, and wind, or from coal-fired power plants that don't need imported oil.

Almost half of the oil used in this country is turned into gasoline. In the long run, converting a significant portion of our transportation to electric or plug-ins will make a huge difference in how our energy is created and used, and on our dependence on oil imports. Assuming we have the sense to start building new power plants, of course.