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Toyota and Panasonic made an announcement today that they would build two new automotive battery factories to satisfy Toyota’s plan to build 1,000,000 hybrid automobiles a year by 2011. One of the new plants will be for Li-ion cells and the other for NiMH cells.
 

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I think Toyota is one of the most conservative automotive companies. NiMH cells have more than 10 years of proven record of safety and longevity. Toyota and Panasonic are still continuing their research for more capacity, smaller/lighter packaging and less cost of this type of battery. As for Li-ion cells it looks like finally they feel confident about their safety, life expectancy and cost, so much so that they decided to build a new factory to manufacture them. Panasonic is one of the first companies to start manufacturing Li-ion cells for laptops and cellphones. They must know a thing or two about Li-ion cells. Just think of one incident of fire of the battery pack at an early stage of the game and the resultant damage to the company’s reputation and the sales of Li-ion battery car in general. You are talking about tens of thousands of cars, not 10 or so Teslas.

As for the drivetrain design, I do not think there is nothing wrong with the parallel design. As I mentioned in the other post, the use of electric motor for start up, idling stop, city runabout and highway acceleration boost is the best approach if you take the very nature of electric motor into consideration, even though mechanically it is more complex than that of the serial design. Until fully electrified practical cars become available this design is the best compromise.

In the serial design if the motor and the wheels are rotating at the same angular speed (in-wheel motor, for example), the problem of back electromotive force should not be so serious since even at the highway speed the motor is running at around 900-1000 rpm (tire diameter: about 2 feet). But in this case you have to worry about not to fry the motors when starting up. (Keio University’s Eliica has 8 sets of wheels and motors to distribute needed torque for quick start up!). If you use a torque/rpm exchange mechanism, you must settle with slow starting acceleration, at the same time devise a mean to counter the back electromotive force at high rpm. For a small car like Mitsu I-MiEV design must be relatively simple, though.
 
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