California Clamps Down on Diesel Idling
On the Wings of a Beetle: ~60+ mpg

Turning the Prius into a Plug-in Hybrid

The California Cars Initiative (CalCars), a non-profit startup dedicated to jump-starting the market for plug-in hybrids (PHEV), is building a prototype Prius (the Prius+) capable of functioning as a plug-in hybrid and running in full EV (electric vehicle) mode for longer distances than possible with the original Toyota equipment.

As designed and programmed, the Prius has a driver-selectable EV (electric vehicle) drive mode. When toggled, EV mode turns off the combustion engine and the Prius functions as an all electric vehicle—particularly good for starting up and neighborhood travel. The default EV driving mode can be used for about one mile with a maximum speed of about 34 mph.  EV mode is not currently activated for Priuses bound for the US, although it is on models in Japan and Asia.

Not being activated is different than not being enabled. The EV mode program logic is still in the ECU—it’s only the button and the wires that are missing. Shortly after the Prius’ arrival in the US, then, enterprising technically-oriented owners began hacking or modifying the Prius to enable EV mode. What started out as a customized D-I-Y (Do-It-Yourself) hack (example here) has become a more formalized aftermarket product (example here).

In EV mode, the software will automatically restart the engine when the battery needs to be recharged, if acceleration is required, or if the vehicle speed exceeds a threshold of 35 mph. In any of those conditions, EV mode switches off and the Prius operates as usual.

As an EV, however, the Prius is not very satisfying. The battery pack wasn’t selected with extended EV operation in mind, and, more critically, the vehicle can’t plug in to recharge the batteries. Staying far away from a plug-in was definitely part of Toyota’s planning. The company went to great lengths during the iinitialroll out of this version of the Prius to point out that it did NOT plug in.

This was clearly a conscious product marketing and design decision. There are a number of hybrids—such as DaimlerChrysler’s new Sprinter vans (earlier post)—that do offer the plug-in option.

Enter CalCars. CalCars decided to use the Prius as a high-visibility platform to demonstrate the fuel economy benefits of a grid-pluggable hybrid that offers an extended EV range.

The CalCars team is adding a different battery pack and grid-charging capabilities. The group has started with a prototype using lead-acid batteries that delivers less than 10 miles of EV-only range at low speeds. They hope to upgrade to a custom-built NiMH pack for an expected range of some 20 miles. CalCars would like to build a second prototype using a Li-Ion battery and hope for a 30+ mile range.

There are still limitations to the Prius as an EV even with those modifications—the Toyota software still rules the ECU, so EV mode will automatically terminate if acceleration is less than gentle, or when the car tops 35 mph. So rather than concentrating solely on the EV results, CalCars is focusing on the increased mileage enabled by the conversion.

As we’d fervently hoped, the batteries contribute significantly to improved efficiency even at higher speeds: Ron showed 83 mpg for a 10-mile mostly-highway run. (Remember that this initial battery pack weighs about 300 pounds -- appropriate for our first tests but not for an acceptable vehicle, and we expect even better performance ahead.) This validates our approach of emphasizing the fuel economy benefits rather than the amount of miles driven in EV-only mode.

—Felix Kramer, Founder California Cars Initiative, Message 226

CalCars tracks its progress and developments via the PRIUS+ Plug-In Hybrid Conversion Group, from which the snippet above is taken. It’s worthwhile taking a look—it’s a good window into what’s involved.

CalCars is also looking for volunteers and donors. Details are available at its website.

(Thanks to Mike C. for the pointer!)



I don't know why car makers are so afraid of plug-ins. Giving the customer the option is not like forcing him/her to do it...

It would be especially profitable here in Quebec where most of our electricity comes from hydro and is relatively cheap.

Jim Summers

While they're at it, they should install solar cells on the roof. Why plug it in when you can just park it in a sunny spot?


As I do a lot of my driving 5 or so miles in a 35 MPH speed zone it would be a great cost saver for me. it might be enough to get me to trade my well loved 2002 Prius in if a 20 mile range was avalable in a plugable hybrid


The battery component of Hybrid technologies offer what Hydrogen cannot: home-based energy. Exxon and company would rather control hydrogen supply, too impractical to generate at household levels. A set of batteries can be recharged via rooftop solar and electric utility grid.

Question: Which technology is more energy efficient:
A Photovoltiac charged battery pack?
Or, the same Photovoltiac electricity supply for electrolysis to isolate, compress and store hydrogen?

Follow-up question: Which technology is more practical and more reliable?

Car manufacturers will not publicly admit that we drive too much, too far, for too many purposes, at too high cost and impact. No. They will only plan for and promise more of the same dependency.

The limited driving range of Plug-in Hybrids offer an economic incentive to build and support local economies; with services, occupations, institutions and amenities, etc, accessable without having to drive. Driving can and should become a travel option alongside walking, bicycling and mass transit.

A 300-400 pound battery pack, located low on a vehicle frame, lowers center-of-gravity; making such Hybrids perfect for SUVs prone to accidental rollover. However, fewer accidents translates into reduced profits from the sale of replacement autos.


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Photovoltaics on the roof and hood of an electric vehicle are quite expensive, and ultimately not really that useful. With the average car's surface area they could kick out a constant 12V at up to 10 amps or so on a sunny day, meaning at best 960 watt-hours during the average useful 8 hour sunny timeframe of the day, so almost one kWh. (We're talking best case scenario here...) And one kWh will take you about 4 miles. So if you're commuting only that distance in a day, perfect. Otherwise it's not enough power. And the cost of the cells would be at least a quarter of the total vehicle price!

Photovoltaics will eventually be quite useful, but probably only in large fixed installations on building rooftops or where you want shade. Another cool trick is you can concentrate the amount of light using mirrors or fresnel lenses, effectively getting more bang for the buck. But that kind of tracking system is really only feasible if you have a good amount of room to work with, such as a building rooftop.

For the question about which is more efficient: charging a battery or pulling hydrogen out of water, charging a battery would be more efficient at the moment, but studies are investigating the potential to use the same system found in plants that splits water to hydrogen in order to arrive upon a more efficient source. Once discovered, that will definitely revolutionize things!

Now if we can just keep the mentality of big oil out of the scene, we'd be set. Not gonna happen with the current US administration.



If you guys or gals are thinking of getting a Prius right now, you should wait for the next generation prius. You can add 10 more miles to todays prius with more features.



I wonder about putting solar panels on UPS/FedEx/USPS trucks. They don't drive many miles per day, and have large flat roofs.

These trucks really seem like a perfect application for hybrid technology.
* They are running on idle/park often, and an engine shutoff would save energy.
* They are in stop and go traffic all day, so regenerative braking might help quite a bit.
* They don't need to accellerate very quickly, since many never see a highway.
* Their large flat roofs would be perfect for solar.


Fedex is exploring hybrid technology currently. It seems that higher fuel prices are helping to wake everyone up. I recently purchased a bicycle equiped with a battery and electric motor. With a little pedaling you can get 30 miles out of a 20 cent charge. Of course bicycles are not for everyone but every the bit helps. Check them out at


Those who complain about the drawbacks of battery power are sorely ignorant of their many, even phenomenal benefits.

Hybrid batteries can form the basis of home-power electricity storage, highly desireable in the event of electricity shortages and price gouging. In this way, they advance the rooftop photovoltiac industry. The battery pack, mounted low on the frame, lowers the vehicle center-of-gravity, improving handling and stability, a major safety factor, perfect for roll-prone vehicles like the SUV. This homepower, zero-emission, battery-only operation effectively reduces fuel costs, a conflict of interest that Big Oil and automakers are actively working to protect by defaming the Hybrid. Some who condemn hybrids are suspect.

Those who tout diesel and bio-diesel fuels do not understand how Hybrids perfect the combustion, emission reduction and economy of these and all other fuels, including hydrogen.

The diesel engine is least efficient during varied accelleration and decelleration. When paired with the Hybrid electric motor drive, the diesel engine rpm range and load are strictly regulated, allowing the electric motor to perform propulsion where the diesel engine fares poorly. This increases diesel fuel mileage, reduces emissions, extends engine life and reduces maintenance.

During the Clinton era, Ford and GM produced Hybrid prototypes, (Ford Prodigy and GM Precept), 4-door sedans similar to the Prius that achieved 70-80 mpg, both employing turbo-diesel engines. Neither incorporated a larger battery pack, as does the next generation Plug-in Hybrid, which can extend zero-emission driving to achieve 500+ mpg.


The fuel cell technology should be trashed. GM has no intention of mass producing any version of the 'skateboard chassis' fuel cell prototypes. Beyond the myriad of problems associated with hydrogen production, storage and distribution, their drive system, the so-called 'drive-by-wire', computerized, electronic steering, braking and accelleration system is extremely problematic. Also, their 'in-wheel' electric motors are likewise impractical, unreliable, maintenance-prone. The combination of wiz bang technologies is dangerously vulnerable chance mishap and system failure from a variety of sources including radio interference. Wake up! The Hydrogen fuel cell is a hoax.

The "Hybrid-drive" is the state of the art vehicular technology. The Hybrid has a long list of advantages over fuel cell, including the ability to burn a variety of fuels including Hydrogen and bio-diesel, all in perfected combustion. The hybrid battery-pack alone has features that extend zero-emission driving, benefit the photovoltiac industry and home-power, and major vehicular safety factors. Hybrids are applicable to all classes of vehicle, unlike the fuel cell which is limited to the lightweight class.

We should however be warned that there are some new car and truck models that do not deserve the title Hybrid. The key to determining which Hybrid is superior is simple: if the Hybrid has an electric motor that can drive the car without running the IC engine, it's a true hybrid. If the Hybrid is merely an electric 'assist', such as the 'contractor truck' models that incorporate an electric generator that only 'assists' the IC engine for nearly all speeds of travel, this version of Hybrid should not be considered Hybrid and does not deserve a tax break or credit.

Most important, beyond the question of which car technology is worthy, urban/suburban travel and transport must include the means and infrastructure for walking, mass transit and bicycling, each of which are degraded when transportation planning is overly-dedicated to any kind of car, no matter how clean burning. Wake up!


Hybrids lead to less driving...
Posted by: Wells on May 25, 2005 12:39 PM

Earlier, I wrote insisting that Hybrids have phenomenal advantages and should be considered the pinnacle of vehicular technology that will not be surpassed by hydrogen fuel cell.

The larger battery packs of the next generation "Plug-in" Hybrid offer major vehicular safety factors, homepower via rooftop photovoltiac and zero-emission fuel economy potential exceeding 500 mpg.

Perhaps the greatest benefit of the homepower battery pack is an economic incentive to drive less. A battery pack has a limited driving range 30-80 miles, (more miles are possible, but not without some costs/drawbacks/limitations). Because the economic incentive of solar power limits driving, short-distance destinations (occupations, institutions, general goods retail outlets, entertainments, amenities, etc) are eventually constructed nearby, locally, and become accessable without always having to drive. Thus, Hybrids leads city and suburban development toward more walking, bicycling and mass transit, (highly desireable for a number of reasons and more economical than driving).


The Hybrid vs Bio-diesel debate seems futile to me. Include hydrogen/fuel cell in the debate, and we're still left with Hybrids as the clear winner by far.

During the Clinton era, Ford and GM produced hybrid prototypes, the Prodigy and Precept 4-door sedans. Both incorporated turbo-diesels and achieved 70-80 mpg. Neither took advantage of adding extra batteries, a technically shortsighted manuever and nod to the fossil fuel industry.

The next generation Plug-in Hybrid, is the quintessential electric car that all manufacturers should drop all else and begin to mass produce.

The life-cycle of state of the art batteries now approaches or exceeds 100,000 miles. But, these batteries create many other advantages beyond longevity. Their weight, mounted low on the car frame, lowers center-of-gravity, improving stability, handling and safety. And of course, hybrid mileage will exceed, 70-80 mpg, doubling and tripling those figures and more.

The photovoltiac solar panel industry has met its match with the Plug-in Hybrid. Every household with rooftop solar panels attains a substantial energy supply not susceptable to fluxuations in the electric utility markets. These households get a invaluable lesson in energy conservation.

Perhaps the greatest lesson Plug-in Hybrids offer is their potential affect upon urban/suburban development. Because their driving range on battery power alone is still limited, they create an economic incentive to patronize and build local economies, whereby over time, more and more destinations become accessable without having to drive. Being able to safely walk and bicycle and take transit is essential transportation planning if modern civilization is to survive the coming collapse of the petroleum industry. Planning simply for the better car is, I repeat, futile.


For the non-hobbyist, plain-old consumer here what is commercially available now and what will be commercially available during 2006 as far as trying to purchase a Plug-In enhanced Toyota Prius?

How quickly are these innovations getting noticed by Toyota and does anyone have any data or information on when a Plug-In Toyota Prius could be purchased (or ordered) and Toyota's reaction to all of this?

Obviously it is in Toyota's own interest to produce & sell a 80 mpg Prius configuration on the market - so what does a regular ol' consumer like me do in the next year to try and get one?

Reply to: [email protected]


The first thing we should is to get Toyota to recall all Prius 2004/5 and have the "EV Mode" switch and wires instaled

Mike Rogers

The reason all automakers wanted to stay away from plug-in hybrids is that too many Americans might get the idea that a pure EV would work well for commuting. Its the "100 monkey" thing, where a new idea often won't "gel" until some number of a population considers it to be good. Once out to the bottle, EV's would have a huge affect on automaker and oil company profits. To the oil companies, they are trying to "manage" the transition away from oil to maximize profit on what remains. To automakers, aftermarket parts sale would take a significant hit with EV's - they're too simple, and last too long.

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