Hybrid Car – More Fun with Less Gas

Toyota announces plug-in Prius

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Posted by Al Falfa on October 19, 2009, 6:35 pm
 



http://tinyurl.com/yzr9fku


Posted by Neo on October 25, 2009, 12:42 pm
 



I have read that Li-Ion EV battery systems have a
shorter lifespan (6 to 10 years) than the current
NiMH EV battery sytems.(10-20 years) . For example,
HyMotion's Plug-in Add-on Li-Ion EV battery
system to the Prius II (2005-2009) is rated for
only about 6 to 8 years before it must be replaced.
Toyota's NiMH EV traction battery system is
warranted for 8 years but reports that I've been
reading suggest it is engineered to last atleast
20 years and upto 300,000 miles.  The key to
NiMH EV battery lifespan technology is the
computer managing the NiMH battery's power
levels and recharging process.  I've read that
NiMH and Li-ion battery recharging characteristics
are different so the same methodology that
has been able to extend the life of the NiMH
EV batteries would not work for the Li-Ion EV
batteries. It is this same  lifespan-warranty
Li-Ion EV battery technical challenge that has
been holding up the introduction of the Chevy Volt.
I would be interested in knowing whether
Toyota has solved this *reported* technical
challenge given the new battery chemistry.

Posted by Al Falfa on October 25, 2009, 9:59 pm
 



I have read that Li-Ion EV battery systems have a
shorter lifespan (6 to 10 years) than the current
NiMH EV battery sytems.(10-20 years) . For example,
HyMotion's Plug-in Add-on Li-Ion EV battery
system to the Prius II (2005-2009) is rated for
only about 6 to 8 years before it must be replaced.
Toyota's NiMH EV traction battery system is
warranted for 8 years but reports that I've been
reading suggest it is engineered to last atleast
20 years and upto 300,000 miles.  The key to
NiMH EV battery lifespan technology is the
computer managing the NiMH battery's power
levels and recharging process.  I've read that
NiMH and Li-ion battery recharging characteristics
are different so the same methodology that
has been able to extend the life of the NiMH
EV batteries would not work for the Li-Ion EV
batteries. It is this same  lifespan-warranty
Li-Ion EV battery technical challenge that has
been holding up the introduction of the Chevy Volt.
I would be interested in knowing whether
Toyota has solved this *reported* technical
challenge given the new battery chemistry.

It seems everyone is getting into the LI-Ion battery market:

http://tinyurl.com/yju8onr


Posted by Neo on October 26, 2009, 10:44 am
 


Li-Ions have a much higher power density than
NiMH so in theory they can increase the time a
hybrid can use electrical power. NiMH based hybrids
only have enough battery power to increase
fuel efficiency by recovering are reusing power
lost during the stop and go part of the ride
and by extending how long a car can "coast" on
its own momentum.  Li-Ion have enough power
to move a car several miles on a charge - it
changes the fuel efficent equation signficantly.

Li-Ions have two technical challenges that I know of
heat dissipation and lifespan.  The heat dissipation is
a linear function of power output and chemistry type
so just by limiting average power output the heat
dissipation problem can be addressed.  I know much
less about the technology to maintaining a stable
battery chemistry for Li-Ion other than high temperature
is a big factor in the chemicals breaking down.
While going to nanotechnology may increase the
power density and output of the next generation
of Li-Ion batteries - it does not address the technical
challenges with heat dissipation and battery
lifespan. Toyota guards its reputation of high
reliablity very closely - so both heat dissipation and
battery lifespan of Li Ion battery systems would
be key technical issues that I am sure they
would address in any application.

Posted by Al Falfa on October 26, 2009, 5:01 pm
 



Li-Ions have a much higher power density than
NiMH so in theory they can increase the time a
hybrid can use electrical power. NiMH based hybrids
only have enough battery power to increase
fuel efficiency by recovering are reusing power
lost during the stop and go part of the ride
and by extending how long a car can "coast" on
its own momentum.  Li-Ion have enough power
to move a car several miles on a charge - it
changes the fuel efficent equation signficantly.

Li-Ions have two technical challenges that I know of
heat dissipation and lifespan.  The heat dissipation is
a linear function of power output and chemistry type
so just by limiting average power output the heat
dissipation problem can be addressed.  I know much
less about the technology to maintaining a stable
battery chemistry for Li-Ion other than high temperature
is a big factor in the chemicals breaking down.
While going to nanotechnology may increase the
power density and output of the next generation
of Li-Ion batteries - it does not address the technical
challenges with heat dissipation and battery
lifespan. Toyota guards its reputation of high
reliablity very closely - so both heat dissipation and
battery lifespan of Li Ion battery systems would
be key technical issues that I am sure they
would address in any application.

Apparently the NIMH battery takes a charge more readily too.  In Prii
modified by the addition of Li-Ion batteries the NIMH batteries are
preserved in order to facilitate hybrid performance.  I don't know if this
is because the Li-Ion batteries aren't suited to this task or if it was
simply a matter of convenience.

Not much information is available regarding the 3G plug-in hybrid Toyota is
testing now but I noticed it's all-electric range is, if I recall correctly,
16 miles.  When I compare that to the 40 miles some 2G modifiers brag about
I have to wonder if Toyota is putting some Li-Ion batteries alongside the
NIMH batteries under the back seat.  If this is the case, it lends credence
to a report I read about the 3G when mention was first made of it:  It was
factory upgradeable to plug-in if/when the technology is perfected.   That
would also explain the EV mode which is presently of limited value.  A
16-mile all-electric range would be very useful for all of my short trips
which for me involve that first five minutes of poor mileage while my hybrid
system is warming up.
 


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