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PHEV FAQ

What is a Hybrid vehicle? Given the immense popularity of the Toyota Prius and other cars like it, most people are now familiar with hybrids. Hybrid simply means the car and run on two (or more) sources of energy; in this case gasoline and electricity. Hybrid vehicles capture energy normally wasted during braking (which was traditionally converted to hot, dusty, worn out brake pads) and it converts it into electricity. This electricity is stored in batteries and used to help the engine use less gasoline. It's like having two people pedaling on a bicycle instead of one.

The electric motors used in a Hybrid vehicle are a great idea since they inherently have highest torque (turning power) and efficiency at low speeds. Gasoline engines on the other hand have practically no torque at low speeds, which is why they need heavy transmissions to convert the high speed of the engine into high torque. By using electricity to help the car go, the car needs smaller lighter transmissions.

What is a Plug-In Hybrid? Even though Hybrids use electricity for greater efficiency, the electricity they use was still ultimately still generated from gasoline. Gasoline as a fuel source is not very efficient (only about 15-20% efficient in cars). Plug-In Hybrids are only slightly different than traditional Hybrids. They have larger batteries for greater electric storage and include a charger so instead of going to the gas station to get your fuel, Plug-In Hybrids allow you to fill up your electricity "tank" using a regular 110V outlet.

With a Plug-In Hybrid all of your local trips are powered by the quiet and smooth electric motor rather than the gasoline engine. If you buy renewable energy (wind, solar, hydroelectric etc.) or purchase CO2 offsets for your electric, your local driving is now Carbon Neutral.

Plug-In Hybrids add additional battery storage capability and have a way (charger) to add electrical energy to those batteries by plugging in. Plug-In Hybrids are clean, quiet and smooth electric cars with a gasoline engine as a backup for greater range.

Why would I want to plug in my car? Plug In Partners VideoIn short, because electricity is cleaner, cheaper and domestically produced and all these facts together have tremendous advantages for us as a individuals and as a society. Cleaner means the less pollution and global warming greenhouse emissions are released into the environment. Cheaper means a dollar worth of electricity will take you further than dollar worth of gasoline. And, domestically produced means we are not dependent on foreign oil. Plug-In Partners has produced an excellent eight minute video on the advantages of plugging in.

What does PHEV stand for? Plug-In Hybrid Electric Vehicle

What is a Plug-In Hybrid Conversion? Given that automakers seem to be unwilling to produce Plug-In Hybrids quickly (even though the technology is extremely simple), individuals and a few companies are starting to convert vehicles themselves. Most of these conversions to date have been done to the Toyota Prius since the design of the Prius lends itself well to Plug-In conversions. These conversions can be accomplished is a variety of ways but all involve the addition of three basic components Ð batteries, charger and control electronics..

How far can I drive in electric vehicle mode? How far primarily depends on the type of batteries used in your conversion. Lead-Acid (PbA) conversions generally have an electric range of about 15 miles while Nickel Metal Hydride (NiMH) and Lithium Ion (Li-ion) conversions have about 30 miles of electric range. Like gasoline vehicles - terrain, climate and driving style will affect the actual range you experience.

How fast can I drive in electric vehicle mode? Currently electric mode speed in the Prius conversions is computer limited to less than 34 miles per hour. For most people, this limitation is still plenty fast enough to go to the store, take the kids to school, or even get to work. It's been said that the motor in the Prius is the same that was used in the freeway capable RAV4-EV so the imposed limit seems to be due to programming rather mechanical limits. (Editor's Note: I'm still looking for a reference on this fact.)

What happens if I drive further or faster than the Prius conversion will allow? The car automatically becomes a regular Prius. If speed is the only limitation and there is still energy in the batteries, the Prius will tend to blend more electric power into the drivetrain which provides better than average Prius mileage.

What if I'm not able to plug in the car? The car becomes a regular Prius with mileage similar to a factory equipped Prius.

Will I really get over 100 Miles Per Gallon? As stated before, your actual mileage will depend a lot on terrain, climate and driving habits. If a lot of your miles are local, off-freeway trips you could experience extremely high mileage in terms of gasoline consumption. Some Prius conversions have seen mileage figures as high as 150MPG. Hills and cold weather tend to reduce the mileage figures of the car.

How much will the electricity cost? The Prius conversion requires around 300 watt hours per mile driven. To determine how much you will spend on electricity, check your electric bill and see how much you pay per kilowatt hour. Multiply that amount by .3 (that's "point three") to determine your electric cost per mile. In 2006, the U.S. the average cost of electricity was $.0986 (that's 9.86 cents) per kilowatt hour so the cost per mile based on this average would be three cents per mile.

How does this compare to the cost of gasoline? Toyota states the combined (city/highway average) MPG for the Prius is 46 miles per gallon. As of October 2007, gasoline was between $2.37 (lowest) and $3.69 (highest) per gallon. This means the Prius gasoline cost per mile is between $.05 and $.08 per mile. If you drive the U.S. "average" car (based on 2007 CAFE fuel economy average of 27.5 miles per gallon) your gasoline cost per mile is between $.09 and $.13.

How long does it take to charge? This depends on the charger used and on the type of batteries in your conversion, but since charging is usually done at night, the 3-5 hour charging time is insignificant for most Plug-In Hybrid owners.

Do I need a special outlet or circuit breaker? For Plug-In Hybrid conversions the answer is no. A regular 110V outlet is used in most cases. Hopefully when automakers make Plug-In Hybrids they will make them with the simple ubiquitous plug we all know. If they don't, this will be a sign they don't really want to see Plug-In Hybrids succeed, since most people do not want their car to require special charging facilities.

How can electricity be cleaner than gasoline when (in most places) it's produced using dirty coal burning power plants? Because gasoline is so very dirty, requires lots of electricity to make and beacause gasoline cars are far less efficient than electric cars. The science behind this is called "Well to Wheels Emissions Studies" and now over 40 studies (some funded by governments, including the U.S.) state that even on today's electricity, electric cars are cleaner than gasoline cars. And as we clean up the grid, plug-in cars get even cleaner. (reference)

First of all, most people don't think about how gasoline is made. We use electricity to drill for oil and then to pump it out of the ground and through pipelines to ships. The ships are usually diesel and have further emissions as they bring the oil across oceans to oil refineries. Then the oil refinery uses A LOT of electricity to convert the oil to gasoline. In fact, California's largest industrial consumer of electricity is oil refineries. We have the gasoline but we're not done yet. Now we use electricity to pump the gasoline into trucks. Then the diesel trucks pollute more as they deliver the gasoline to the service stations where it's put into the ground. Then we use electricity again to pump the gasoline into our cars. Have a look at this illustration to see what we mean.

All of this electricity used for a fuel that only yields 14% average efficiency in our cars. That's right, gasoline is only 14% efficient as a fuel source in gasoline cars. Most of the energy contained in the gasoline is converted into heat when it's burned. Then of course, there is the pollution created by cars. It's nearly impossible to insure that every car, of the estimated 500 million on the planet, are tuned to run as clean as possible. On the other hand, regulating and cleaning up the emissions of a relative handful of power plants is possible and is already being done. Now, compare the above to electricity. First of all, electricity can be produced using clean renewable methods including wind, solar, hydro-electric, tidal currents, and geo-thermal. But even if we are using coal or other polluting methods to produce the electricity, once the electricity is produced there are no more emissions. The electricity travels to your home at the speed of light with line losses of only about 7% (reference). Then the electricity is put into your car with battery and mechanical losses of about 25%. As you can see electricity as a fuel source is much more efficient than gasoline. (reference).

If people start driving Plug-In Hybrids, won't this burden the electrical grid? Major utilities like Pacific Gas & Electric and Austin Energy have studied this and found since Plug-In Hybrids are generally plugged in at night, the grid already has the nighttime capacity to charge these vehicles. A January 2007 Pacific National Laboratory study showed that if we woke up tomorrow and all our vehicles could plug in, today's grid could already support 84% of them charging at night without building a single power plant. (reference) An earlier study by The Electric Power Research Institute (EPRI) estimates that the current power grid could handle many tens of millions of cars plugging in at off-peak hours before we'd have any capacity issues (reference).

Seems like Plug-In Hybrids are a step toward all electric vehicles, but aren't electric vehicles slow and ugly (like a golf-cart)? YouTube FastEVs Playlist This is one of the biggest misconceptions about electric vehicles. Yes, golf carts might be slow and ugly but electric cars don't have to be, Did you know the quickest motorcycle in the world is electric? Check out these videos of electric cars like the Tzero and White Zombie and tell me if you still think electric cars are slow. The Telsa Roadster does 0-60 in under four seconds and looks beautiful while doing it.

Don't electric cars have a limited range? It's true an all electric car usually has a shorter range than a gasoline powered car, but most still have a range that's more than adequate for most of our daily driving. For example the average American drives about 30 miles per day and the RAV-4EV has a range between 80-120 miles depending on terrain. And, despite this vehicles age most owners report no degradation in performance or range. The Telsa Roadster has a stated range of about 220 miles.

Still, limited range and the perhaps unrealistic fear of getting stranded with empty batteries is why Plug-In Hybrids are the next revolution in automotive development.

Isn't Toyota going to produce a Plug-In Hybrid next year? There have been reports that Toyota plans to sell a Plug-In Hybrid by 2010. Based on these reports, the good news is these Plug-In Hybrids will have a top electric speed of 60 MPH. The bad news is the cars will only have an EV range seven miles. That said, I'm ready to buy Toyota. Where do I sign?

I have a Honda Insight, can it be converted to a Plug-In Hybrid? Unfortunately, the Honda Insight and some other hybrids use a different method of integrating the electric motor power with the vehicle drivetrain. In this method, the electric motor can not propel the vehicle on it's own. That said, if you are not planning to convert the car to a Plug-In Hybrid conversion, the Honda Insight is an excellent car in terms of fuel efficiency.

So what cars can be converted to become a Plug-In Hybrid? In theory, any cars that use the Toyota Synergy Drive (TSD) can be converted to a Plug-In Hybrid. These cars include the Toyota Highlander, Toyota Camry, Lexus Hybrids, and the Ford Escape (they licensed portions of the TSD from Toyota). Editors note: Are there others?

To date, except for the Prius only one Ford Escape has been converted. This is perhaps partly due to the advantages of the Prius EV mode button that are not know on other vehicles. Still many are anxious to see conversions done to other types of vehicles.

What is the cost of a conversion? A bare bones do it yourself (DIY) conversion could conceivable cost as little as $4,000. Your primary expenses would be for items you cannot make yourself such as batteries, charger and CAN-View interface. The above does not include a professionally made battery and electronics enclosure which is highly recommended for crash safety.

Given the cost, why would I want to convert my Prius to a Plug-In Hybrid? Where's the payback? That said, people are choosing to convert their Prius to Plug-In Hybrid for a variety of reasons.

  • Some people prefer to refuel at home by plugging in.
  • Some people want an electric car because it's smooth and quiet and converting a Prius to Plug-In is an easy way to get this, at least part of the time.
  • Some people are taking climate scientists warnings seriously and feel it's their responsibility to do anything they can to mitigate Global Warming, if only on a personal level.
  • Some people want to show others that the automakers are lying to us when they say Plug-In cars are not technologically feasible.
  • Some people feel it's patriotic to by domestically produced electricity rather than foreign oil.
  • Some people have solar installed on their house and want to capture an additional benefit from their solar investment in the form of free transportation.


Regarding "payback", it's interesting people will happily pay extra for upgrades like leather seats, rear seat entertainment systems, and premium trim packages. Some people will spend $50,000 on a Hummer and spend even more in aftermarket upgrades because it fits their personality. But, if someone chooses a fuel efficient environmentally friendly car because it fits their personality and values, they may be chided because there is no "Payback". Leather seats or a rear seat entertainment system do not offer a payback , except that like an "environmental package" they make the owner feel good.

If you are solely looking for individual payback, an aftermarket Plug-In Hybrid conversion at this point is probably not for you given the initial cost of the conversion. However, it's estimated that if the automakers ever produce Plug-In Hybrids it will only add $2000-3000 to the cost of the car. A 2003 EPRI study assuming only $2/gallon gas, zero buying incentives, and a PHEV premium of $3-$5,000 more than standard hybrids, shows that the total lifetime cost of ownership for a PHEV will be lower than that of any other vehicle type -- so a financial return for the owner will be there.

Won't a conversion void my warranty? An automaker could decide your warranty has been voided from the conversion. However, to date no Plug-In Hybrid owner has had a problem with their Prius that tested this situation. The good news is there is legal precedent set by aftermarket modifiers that found auto warranties cannot be voided completely by modifications, and that only the part(s) affected by retrofit will have their warranties voided.

It's perhaps important to understand that dealers get paid by the manufacturer for warranty repairs. So it's not in their best financial interest to unfairly blame a failure the Plug-In Hybrid conversion. In some cases they may choose not to bring up the issue at all. Some Plug-In Hybrid owners have been enthusiastically greeted by local Toyota technicians who themselves are very interested in the Plug-In Hybrid concept.

In the event of a warranty related repair, it might be a good idea to talk to a few dealers in advance of them seeing your vehicle identification number to see if they will be a friend or foe of your converted Prius.

Doesn't the conversion add a lot of weight to the car? Depending on the batteries chosen, the conversion will add approximately 150-300 pounds to the weight of the car. This will lower the rear ride height by about two inches. We are looking for a custom spring retrofit that will bring the ride height back to normal.

Are Plug-In Hybrid conversions dangerous? Without the sophisticated engineering and testing that occurs by automakers, it's impossible to fully know if a conversion is any more dangerous than a stock car. A lot will also depend on the quality of construction and care taken during a do it yourself conversion.

The battery pack has high DC voltage that can be dangerous and even deadly if not respected. Only persons trained in working with high voltage electrical systems should work on Plug-In Hybrids or traditional hybrids for that matter.

Perhaps the biggest concern is how the additional weight and mass (batteries) added to the rear of the vehicle will behave in the event of an accident. While companies selling conversion components are now beginning to do crash testing of the battery box, ultimately it's the responsibility of the vehicle owner to decide if the benefit of having a Plug-In Hybrid conversion is work the additional risk of having systems that have not undergone the level of engineering and safety that automakers put their vehicles through.

I have experience working with high voltage electricity and would like to convert a Prius myself. Where can I learn how? This site plans to develop detailed instructions and video tutorials that should help the do it yourselfer create a Plug-In Hybrid conversion. In the meantime, open source plans, schematics and other information can be found at priusplus.org (for a simpler conversion based on SOC drift) and www.eaa-phev.org/wiki/PiPrius_conversion_process(for a more complex conversion based on a DC:DC converter.

I don't think I have the skills necessary to do this conversion myself, can I hire someone to do it for me? There are a few companies available to do your conversion now, and others have stated the will begin converting in early 2008. Here is the list in no particular:

 
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