Frankfurt 2007: More on the Mercedes hybrid using lithium batteries
In our reports on the Mercedes-Benz S400 and S300 Bluetech hybrids we mentioned that the cars use a lithium ion battery. Both of these cars, as well as the C-Class hybrid that Mercedes is displaying at the Frankfurt Motor Show, use a new mild hybrid system. The mild hybrid system was co-developed with BMW although the Munich brand has yet to show any of their applications. A mild hybrid system can't drive the vehicle on electricity alone so it doesn't need as much battery capacity as a strong hybrid like the Two-Mode system in the ML450.
In order to optimize the packaging of the system to allow it to be easily installed in many vehicles, Mercedes is placing the battery pack under-hood by the engine. Limited under-hood space means a nickel metal hydride battery was out of the question. The lithium pack is being supplied by Johnson Controls-Saft which is also one of the development suppliers to the Saturn Vue PHEV program at GM. Since GM has indicated that they have no interest in pursuing lithium metal oxide chemistries (those are the kind used in laptops that have nasty thermal problems), it's likely the JCS unit for Mercedes doesn't use this type either. The first of the Mercedes S400 hybrids is due to launch in 2009 at about the same time as the PHEV Saturn Vue. It remains to be seen which one makes it to market first.
[Source: Automotive News - Sub. req'd]
Reader Comments (Page 1 of 1)
Chris M 5:13PM (9/15/2007)
Saft has been researching iron phosphate electrodes for LiIon batteries, just like Valence and A123. Li Iron Phosphate can tolerate higher temperatures than cobalt oxide LiIon, but I'd still question the wisdom of placing it near the hot engine.
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