1. How is a Plug-In Hybrid Electric Vehicle (PHEV) different than a normal hybrid car?
Both a normal hybrid and a Plug-In Hybrid Electric Vehicle (PHEV) have a gasoline engine that is assisted by a battery-powered electric motor. The only difference between a PHEV and a regular hybrid is that a high capacity battery is installed into the PHEV that can be charged by plugging it into a regular 120-V outlet (say, in your garage or outside your house). Since the PHEV has more battery capacity and can be fully charged from an electric outlet, the PHEV can use more electric power from the batteries for driving than a normal hybrid; it therefore consumes less gasoline than a normal hybrid and much less than a normal car that has only a gasoline engine.

2. So you are telling me that you can’t plug in a normal hybrid?
No, you cannot plug in a normal hybrid. The battery in a normal hybrid is charged only by recapturing energy from braking and deceleration, not from being plugged in.

3. Will the PHEV still recapture the energy from braking and deceleration?
Yes, a PHEV can still recapture the energy from braking and deceleration.

4. What happens when the PHEV’s batteries are depleted?
When the PHEV’s battery is fully depleted, the PHEV then still behaves like a normal hybrid.

5. Is a PHEV an “all electric” vehicle?
No. A PHEV is not an “all electric vehicle” and cannot run in all-electric mode. A PHEV will still use the gasoline to run the engine for acceleration over 30 MPH.

6. If a PHEV isn’t “all electric” and still uses gasoline then what is the benefit?
Just like a normal hybrid, when stopped at a red light the PHEV’s battery powered electric motor will keep the engine running. When pulling away from the red light, the electric motor will be solely used for acceleration up to 30 mph, then gasoline will start to power the engine. For a normal hybrid, the battery can only accelerate the car to 15 mph, then gasoline will start to power the engine. Since much gasoline is used during this type of “stop-and-go” driving, the PHEV saves much gasoline for in-city driving.

7. How large is the battery?
The battery in Central Hudson’s Prius PHEV is a lithium-ion battery (just like the one in your cell phone or laptop). It weighs approximately 180 pounds and can store 5 kilowatt-hours of energy.

8. How long does it take to charge?
It takes approximately 5 ½ hours to charge the battery. It works just like a cell phone battery charger and will stop charging when it is at its full capacity.

9. How many years do these batteries last?
The popular belief in the industry is that the stock batteries that come with normal hybrid cars (which are usually nickel-metal hydride batteries) will last approximately 8 to 10 years.

10. Are lithium-ion batteries safe?
The lithium-ion battery installed in the Central Hudson PHEVs are safe, and meet UL certification standards and have been certified for use in transportation. Extensive safety precautions also have been taken at the system level. The modules contain battery management systems that monitor the voltage of each cell in the pack along with the temperature of the battery modules. This information is fed into the electronics controller, which automatically terminates charge or discharge in the event that any safety limits are reached. The battery module is equipped with a number of over temperature switches inside the battery pack that will automatically disconnect the batteries, if necessary, without the controller's intervention. Further, the packs have been crash tested in accordance with National Highway Transportation and Safety Administration (NHTSA) regulations, passing all tests.

11. How much does a retrofitted Prius PHEV cost?
A Prius starts at $21,500 (sticker price for a base model). It cost $9,995 to install the extra lithium-ion battery and convert the car to a PHEV. (All costs were paid for under the Central Hudson Research & Development budget).

12. That seems like a lot of money to pay for a PHEV. How long is the payback period?
Right now, the payback period for this specially retrofitted PHEV is long (approximately 6 to 8 years compared to a traditional gasoline powered car). When PHEVs start to become mass produced and the battery cost is lowered, the payback period will be shortened. If the price of gas remains high and tax credits are granted for the purchase of these PHEVs, then the payback period will be reduced even further. The type of driving (in-city vs. highway) and the amount of miles traveled during a typical commute and yearly must be considered in any payback calculation.

13. Where can I get this conversion done?
Central Hudson’s Prius was converted by A123 Systems in the Boston area. The Ford Escape Hybrid conversion was completed by Hybrids Plus in Boulder, Colorado. There are other companies in the country performing these types of conversions.

14. Will a conversion void my warranty?
Companies could decide that conversions void some or part of your car or hybrid system warranty unless they worry that will tarnish its green image. We won't know how dealers will respond to service requests until we start driving converted cars. However, there is a legal precedent set by aftermarket modifiers arguing that original auto warranties cannot be voided completely by modifications, and that only the part(s) affected by retrofit will have their warranties voided.

15. Will and when will PHEVs become commercially available?
PHEVs are not yet in commercial production. However, several automobile manufacturers have announced their intention to introduce production PHEV automobiles soon.

16. Don't PHEVs just shift pollution from gasoline cars to power plants?
Yes, but total pollution will be greatly reduced. With the introduction of more renewable sources of power (including wind, biomass, hydroelectric, etc.), more power to charge these vehicles will come from renewable sources. Even for coal burning plants, it is easier to clean these types of central power plants than millions of vehicles.