Toyota announces plug-in Prius

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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:

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Reply to
Al Falfa

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.

I'm just happy I got a 2004 Prius after reading that. :)

Reply to
Lu R

yes.

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.
Reply to
Al Falfa

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