EDrive Systems LLC releases FAQ
Q1: Why plug-in hybrids (PHEVs)?
A: Plug-in hybrids offer the best chance of transitioning away from fossil
fuels towards a renewably powered transportation future. Full sized
electric vehicles suffer from limited range and may require up to 3 times
the battery capacity of an EDrive equipped plug-in hybrid and still not be
capable of satisfying 100% of a personís driving needs. At present,
hydrogen fuel cell powered vehicles suffer from astronomical cost (over
$500,000), limited range (80-180 miles), low efficiency (compared to
batteries) and most notably a lack of economically priced and widely
available fuel. Plug-in hybrids however can be built today and provide a
no-compromises solution that moves us away from fossil fuels.
While none of these solutions (including plug-in hybrids) can stand
alone on an economic basis today, with rising fuel costs, improved battery
performance and reduced battery cost, plug-in hybrids offer the best hope
of becoming economically viable within the next 5 years. EDrive Systems LLC
aims to prove the concept for those early adopters willing to show the
world that vehicles can be renewably powered without compromise and that we
can move towards a cleaner, more renewable future. Many others may choose
PHEVs as a solution that can be powered by U.S. energy sources without
paying the hefty price of supporting countries that might not have our best
interests in mind.
In the future, plug-in hybrid gasoline cars may give way to plug-in
hybrid ethanol or bio-diesel powered cars. If an economical,
environmentally friendly source of hydrogen is ever discovered, plug-in
hybrid fuel cell vehicles could provide a less expensive, more efficient,
and less range limited solution than a pure fuel cell vehicle.
Battery solutions such as electric vehicles and the EDrive plug-in
hybrid can turn over 80% of the source electricity into usable power for
the wheels (after battery and charger losses). Creating hydrogen from
water/electricity electrolysis and then compressing the hydrogen for
vehicle storage and running the hydrogen through a vehicle fuel cell system
may result in less than 20% of the source electricity reaching the wheels.
Per unit of power, advanced lithium batteries are also less expensive than
fuel cells, meaning that a vehicle with less fuel cell and more batteries
would be less expensive. A plug-in hybrid fuel cell vehicle would also be
less dependent on a sparse hydrogen infrastructure as most of the daily
driving would come from the economical and convenient nightly home recharge.
No matter what the ultimate future renewable vehicle fuel may be,
electricity will certainly play a major role. Plug-in hybrids build a
bridge between any electrical source and any other vehicle fuel, providing
many of the advantages of an electric vehicle with the long range and quick
refueling offered by other fuels.
Q2: Doesn't plugging in the car just trade oil pollution for coal pollution?
A: Californians are spoiled by one of the cleanest electrical grids in the
U.S., but even where coal supplies much of the electrical power, plugging
in vehicles is still a smart environmental solution. One thing that is
often overlooked when electric power plant pollution is discussed, is the
upstream pollution required to extract oil, transport it, refine it,
distribute the gasoline then refuel a vehicle (vapor emissions). Comparing
the national electrical grid to the average gallon of refined gasoline
shows that the upstream pollution for gasoline production on average is
much higher than that of the average electricity source.
Plug in vehicles charge at night when electricity is cheapest and most
widely available on the grid. While electricity may be produced by
renewable or non-CO2 producing sources, fossil fuels at present cannot.
Q3: What is the EDrive system for the Toyota Prius and how does it work?
A: The EDrive system replaces the existing Prius NiMH battery and Toyota
battery control computer with a larger Valence Saphion lithium-ion battery
and a proprietary battery monitoring and control system developed by
EnergyCS. The new system allows the Prius to be charged at home using a
standard 110/120V home outlet. With the larger battery, the Prius can run
in electric only 'EV' mode at lower speeds or when less power is needed.
The result is EV driving and electrically boosted gasoline driving for the
first 50 to 60 miles with a gasoline efficiency of 100 to 150mpg. After the
50-60 mile 'boosted' range, the vehicle performs just like a standard Prius
until it is plugged in again. The battery system is approximately 3 times
larger than the Toyota NiMH battery and is installed under the rear cargo
carpet. A small display is mounted on the dashboard.
Q4: How do I activate these special EV modes?
A: The entire system is automatic. Just drive the car like a standard Prius
and the EDrive system will use electricity whenever possible to reduce
Q5: What is the driving experience like with an EDrive equipped Prius?
A: After the nightly re-charge, the vehicle can be driven in EV mode until
the vehicle speed exceeds 34mph. At this point the engine may start in
order to warm up the emission control system. After the emission system is
warmed up, the Prius will use the gasoline engine whenever higher speeds or
power levels are needed, but will always (for the first 50-60 miles) inject
electricity to reduce gasoline consumption. It is possible to drive in EV
mode at speeds over 34mph and up to 55mph if the power requirements are low
enough. The dashboard mounted display will always tell you if you are using
gasoline and if not, how far you can press the accelerator without turning
the gasoline engine on. In low speed city driving and 55mph freeway driving
it is possible to average over 200mpg. More aggressive driving over 65mph
will lower the efficiency to 100mpg or less. For example, 75mph freeway
driving could result in less than 80mpg. During the 50-60 mile boost
period, the Prius battery display will show either 7 or 8 green bars (ie
full). After the boost mode, the display (and vehicle performance) will be
identical to a standard Prius.
Q6: Why the big difference between 55mph and 75mph?
A: Because of the configuration of the Prius, electric use is limited to
21kW and often less. At speeds over 34mph, the electrical contribution is
more or less constant. You may find at 55mph that 1/4 of the power is
coming from gasoline and 3/4 from electricity, but at 75mph the
contribution may be 2/3rd gas and 1/3rd electric. Even though the electric
contribution is the same in both cases, the gasoline contribution (and thus
mpg) can be dramatically different.
Q7: Can I really get over 200mpg with EDrive on my Prius?
A: Yes, but it requires low speeds (55mph freeway) and mild acceleration in
city driving. Most Prius EDrive users will likely get closer to 100mpg.
Q8: How long does it take to charge?
A: The EDrive lithium battery system is 9kWh or kilowatt-hours (7 times
larger than the Prius NiMH battery). The charger used by the EDrive system
is 1 kilowatt (kw), about the same as a hair dryer. If the battery were
totally depleted, it could take 9 hours (9hrs * 1kW = 9kWh) to charge the
Q9: Can the charger work on 240V power as well?
A: Yes, but the charge speed will be the same (1kW).
Q10: What is the EV driving range?
A: If you were to limit your speed to 34mph or less, the gas engine may not
come on for up to 35miles.
Q11: How is the EV range so much larger than a standard Prius with only 7
times as much battery?
A: The standard Prius has a 1.3kWh NiMH battery but only uses about 25% of
it (or 300Wh). The EDrive lithium battery is 9kWh but up to 80% of it is
used (or 7200Wh). Therefore the EDrive system actually has 24x more energy
(7200/300) at its disposal.
Q12: How much does it cost to charge the car?
A: A full charge could take 9kWh of electricity from the wall socket, but
on days when the car is driven less than 50 miles, the electricity needed
to re-charge will be less. If your electricity cost $0.10/kWh (about
average) then a full charge would be just under a dollar.
Q13: What happens if I forget to plug in the car?
A: Then the vehicle will behave exactly like a normal Toyota Prius. (ie ~50mpg
Q14: Is fast charging available? Can I use public EV charging spaces?
A: The EDrive system was designed for only a 1kW charger with the intent of
being slow charged at night when spare electricity is most available on the
grid. Unlike an electric vehicle that might need additional charging during
the day, a plug-in hybrid can still be driven as a gasoline hybrid after
the battery is depleted (50-60 miles into the day). EDrive is not planning
to offer higher speed charging as it shouldnít be needed and would only
increase the system cost.
Q15: Can more batteries be added to increase the electric/boost range?
A: EDrive was designed for 50-60 miles of boost as this was just beyond the
average driving requirements for most consumers. Ideally the battery should
be sized in order to balance utilization, cost and battery life. At 50-60
miles boost range, there will be many days when the battery is only 1/2 or
2/3rds used, which will greatly increase battery life.
Q16: Why were Valence Saphion Lithium batteries selected for EDrive?
A: The Valence Saphion technology provides a much safer lithium-ion battery
than most standard manufacturers as the chemical composition dramatically
reduces the risk of fire under extreme conditions (such as cell rupture
during a severe collision). Additionally, the Valence lithium ion has shown
much improved cycle life compared to competing manufacturers. Safety and
long life are primary concerns for vehicle applications.
Q17: How long will the lithium battery last?
A: Testing indicates that the Valence batteries should last 6 to 8 years in
an EDrive equipped Prius, with the possibility of 10 or more years being
likely. Depending on how the 'end of life' is defined, the battery may last
the life of the vehicle (ie if 30 miles of boost range is deemed sufficient
from a system that initially provided 50-60).
Q18: How much does the EDrive battery weigh?
A: The EDrive battery pack weighs approximately 250lbs. The Toyota NiMH
battery removed from the vehicle weighs over 70lbs. The net weight increase
is thus approximately 180lbs.
Q19: What happens to the existing NiMH Prius hybrid battery?
A: It is removed during the EDrive system installation process.
Q20: Does the EDrive system affect any other part of the Prius (like the AC)?
A: Many of the Prius subsystems (such as AC) are already electric. The
Prius was designed to have electric driving modes, EDrive merely enhances
the existing system.
Q21: How safe is the EDrive option?
A: The EDie=C system is designed with safety in mind. The Valence Saphion
lithium batteries provide exceptional safety and the rear battery pack is
being designed so as to have minimal effect on the existing rear crumple
zone in case of a collision.
Q22: When can I get EDrive installed in my 2004/05 Prius?
A: Our goal is to have the commercial EDrive product available in early 2006.
Q23: Where can I get EDrive installed in my 2004/05 Prius?
A: Initially, all installations will be done at Clean-tech in Los Angeles.
Q24: Will it be available outside of California? When?
A: As far as the U.S. market is concerned, we are concentrating on Southern
California first. Within 9 months of the initial sales in L.A., additional
authorized retail/installation locations will be set up in other parts of
Q25: How long does it take to install EDrive in a Prius?
A: It should be possible to install an EDrive system in your Prius in less
than one business day.
Q26: How much will the EDrive conversion cost?
A: Our goal is to offer the conversion to consumers at under $12,000. Final
pricing cannot be determined until the commercialized version has been
Q27: Is EDrive available as a user-installed kit?
A: No. Only EDrive certified and trained installers will be installing
systems. The installation involves working with high voltage and sensitive
electronics which require specialized training.
Q28: How does this affect my Toyota Warranty?
A: If a warranty claim were disputed by Toyota, Toyota would be responsible
to show how the modification caused the problem. As the EDrive system never
touches anything under the hood of the car (engine, motors, hybrid
controller etc) it is not clear how this would be handled. Fortunately
being a Toyota product, the Prius has shown to be an extremely reliable
vehicle and we don't anticipate any changes in reliability with the EDrive
Q29: What will be the Warranty on the EDrive system?
A: The warranty for the EDrive installation, electronics and Valence
batteries is yet to be determined. The details of the warranty will not be
known until the commercial product is released.
Q30: Will EDrive work on Honda hybrids?
A: While it may be possible to inject some electrical energy into the Honda
IMA system, because the Honda motors and battery system are less powerful
than the Toyota Hybrid Synergy Drive system and offer no EV mode
capability, the performance improvement from plugging in would probably be
Q31: Will EDrive work on pre-2004 model Prius vehicles?
A: There are no plans at this time to offer EDrive for pre-2004 Prius.
Q32: What other hybrids will EDrive be available for? When?
A: Following the roll-out of the commercial EDrive system for Prius, EDrive
aims to bring this exciting technology to other 'full-hybrid' vehicles such
as the Ford Escape hybrid, Lexus 400h and Toyota Highlander hybrids.
Q33: Can EDrive be installed on non-hybrid vehicles?
A: EDrive makes use of the existing full hybrid system on vehicles like the
Toyota Prius. There are no plans to offer EDrive options for vehicles that
do not already incorporate a full hybrid drive system.
Q34: How is Toyota involved?
A: Toyota has not been involved in the development of the EDrive system for
the Prius and is not presently involved in EDriveís efforts. Toyota has not
endorsed EDrive nor has Toyota discouraged it (aside from warranty issues
yet to be discussed). We suspect Toyota is as curious as we are about how
the early plug-in hybrid market will develop.
Q35: Is there any way to add solar power to the EDrive system?
A: While solar panels integrated on a vehicle roof could partially recharge
the batteries during the day (3-4 miles of additional range) on a Toyota
Prius, this might degrade the vehicle aerodynamics significantly. Home
rooftop solar could allow EDrive customers who choose to install such
systems to harvest a large portion of their vehicle power from renewable
solar energy. Similarly, those who have the option of buying renewable
power for their homes can use the clean power to displace gasoline with an
Q36: How is EDrive Systems LLC associated with CalCars?
A: EDrive Systems LLC is not in any way associated with the California Cars
Initiative (CalCars). Unlike EDrive, EnergyCS and Clean-Tech, CalCars is a
non-profit advocacy group and is not involved in technology development. We
fully support the advocacy and outreach efforts of CalCars to raise public
awareness of the benefits of plug-in hybrids, but there is no financial
relationship between EDrive Systems LLC and CalCars.
Q37: Is the EDrive system gas-optional? (ie: a GO-hybrid)
A: No. While the historical definition of a plug in hybrid might be closer
to that of an electric vehicle with a gasoline range extender, the EDrive
system takes advantage of the sophisticated full hybrid systems in vehicles
like the Toyota Prius and Ford Escape hybrid. As such, the system is not
presently designed to be fully capable at any speed in EV mode, but rather
to share the burden between gasoline and electricity depending on vehicle
operating requirements and operator demands. In the future, we anticipate
the electrical contribution growing and the gasoline contribution
shrinking, but at the moment the EDrive system for the Prius is not really
Q38: Will EDrive Systems, EnergyCS or Clean-Tech become a publicly traded
A: At the present time there are no plans for any of the EDrive partners to
If you have additional questions, please e-mail us at mailto:
info@.... Your question may then be included in our next
update of this FAQ page.
Specifications of the commercial EDrive system for the 2004 and later model
year Prius are subject to change without notice. The questions and answers
in the FAQ do not constitute a specification for the EDrive system.