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2008 Prius details announced: lithium-ion and 94 mpg (US) - Page 2

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Posted by Michael Pardee on April 30, 2006, 1:36 pm

I have doubts about the Li-ion battery. Russel Frost of the Prius Owners
Group recently wrote to (unnamed) Toyota's National Manager for Advanced
Technology Vehicles, and posted parts of her response on
http://www.priusownersgroup.com/  (be aware the content will change, so this
URL will quickly go stale).

She says of Li-ion and plug-in capability: "The extended electric mode in
Japan..which locks out the gas engine and uses only the electric motor.. is
a system that quickly depletes the battery. With current battery technology,
the system can only run for a few minutes. It also depletes the battery
charge significantly. If battery power is constantly drawn down to lower
levels, then recharged..then drawn down, it significantly reduces the
battery life. While there are technically no mechanical issues converting to
a plug-in hybrid system, it will need a lithium ion battery. In two years we
will see them as a power supply and after that, in five years, as an energy
storage device. Based on our testing, the NiMH batteries have no age limit.
Lithium ion does have an age-related lifespan. So we won't introduce such a
pack until we have all the durability issues worked out as well as costs - -
the battery is the most expensive component of the hybrid. In addition, NiMH
batteries are not considered hazardous materials, Lithium Ion is a hazmat."

I don't understand the part about a "power supply" at first, then a few
years down the road as an "energy storage device." I guess it means Li-ion
can be used as a supplement to NiMH to allow plug-in capability (maybe as an
option?) and that it is hoped to be a replacement for NiMH in five years.
Only a guess.


Posted by Jim Higgins on April 30, 2006, 2:19 pm

Thank you for the info Michael.

Posted by mrv@kluge.net on May 1, 2006, 11:31 am
Michael Pardee wrote:

My guess:

Power supply = source for power for the electric propulsion motor in
the current Prius design.

Energy storage device = place where electricity is stored, either from
the grid (plug-in hybrid) or from a hydrogen power souce (all
hydrogen-powered vehicles are really EVs with an on-board generator).

I still would be leary of any 2008 predictions.  Toyota's longest lead
on the upcoming Prius was for the 2004 model year, announcing it in
March/April 2003 at an auto show, for an October delivery (pre-orders
didn't start until July).  (and 2003 Prius sales plummeted partially
because of the announcement...)  Speculative 2006 info was only
released around May 2005, official info in Nov. 2005 (about when the
2006s started arriving).

I also would be leary of any MPG predictions, as that would really
depend on the test course used to estimate MPG, and the type of gallons
used (US or Imperial?).  for example:

US 2005 EPA ratings are 60MPG city, 51MPG highway, 55MPG combined. For
comparison units:
City = 3.9l/100km or 72MPG Imperial or 25.5km/l
Highway = 4.6l/100km or 61MPG Imperial or 21.7km/l
Combined = 4.2l/100km or 66MPG Imperial or 23.4km/l

Canada  2005  OEE  ratings  are  71MPG city, 67MPG highway, but that's
Imperial  gallons.  The ratings are also listed as 4.0l/100km city and
4.2l/100km highway. For comparison units:
City = 59MPG (American) or 25.1km/l
Highway = 56MPG (American) or 23.7km/l

UK 2005 VCA ratings are 56.5MPG urban (cold), 67.3MPG extra urban, and
65.7MPG combined, again Imperial gallons. For comparison units:
urban  (cold)  =  47MPG  (American),  or  5.0l/100km  urban (cold), or
extra urban = 56MPG (American), or 4.2l/100km, or 23.8km/l
combined = 55MPG (American), or 4.3l/100km, or 23.3km/l
http://www.vcacarfueldata.org.uk/search/vehicleDetails.asp?id 982

Japan  2005  using  the  10-15 cycle is (if my Japanese translation is
right) 35.5km/l or 33.0km/l depending on option grade. That's
2.8l/100km  or  83US  MPG or 100 Imperial MPG, and 3.0l/100km or 77 US
MPG  or  93.2  Imperial  MPG.  I  do  note  a  OnMouseOver note that's
something about 30.0km/l though...

The  difference is in the governmental test methods to derive the fuel
economy figures.  You  can  get  some  pretty  graphs  of many of the
different tests here:

BTW: handy online converter site:

Posted by Michael Pardee on May 1, 2006, 7:04 pm
Ah - that makes more sense.


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