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John Petersen
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John Petersen is the executive vice president and chief financial officer of ePower Engine Systems, Inc., a Kentucky-based enterprise that has developed, built and demonstrated an engine-dominant diesel-electric hybrid drivetrain for long-haul heavy trucks that promises fuel savings of 25 to 35... More
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Fefer Petersen & Co.
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  • If lithium-ion batteries are so darned safe, why will the Volt need all that armor? 6 comments
    Mar 28, 2010 4:50 AM
    Autobloggreen just published an article on GM's plans to pare the specifications on future generations of the battery pack for its Voltec drivetrain. While the article's primary concern was that the battery pack would be smaller and die sooner, I was shocked by the picture of the current volt battery pack.

    I'm a natural born cynic, but when I look at the picture I see an awful lot of armor on the top side of a supposedly safe battery pack and have to wonder, if the lithium-ion batteries are so darned safe, then why will the Volt need all that thick formed metal for the case? Was it an engineering question or a legal liability question?

    At first I wondered whether the case might be plastic or some sort of composite, but the mounting holes that are clearly visible along the bottom front edge have a sheen to them that one doesn't ordinarily see in non-metal components.

    Disclosure: No public companies mentioned.
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Comments (6)
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  • Mark Divy
    , contributor
    Comments (214) | Send Message
    I would also wonder where they plan to place this battery. Such an odd shape, makes one think it would be over the drive shaft and rear seat? Have not seen that view of the design. My Prius only uses half of my fold down back seat - granted with much less storage capacity. As for the armor - may be some type of composite, but I bet this is for protection from the Lithium Ion battery tendancies to burn or get very hot - as in some older laptop computer fires. Not sure what the operaitng parameters are for these, but if they are even close to the passenger area, armor might be a good thing.
    29 Mar 2010, 09:16 AM Reply Like
  • John Petersen
    , contributor
    Comments (30726) | Send Message
    Author’s reply » As I understand the design, the main body of the battery will run down the hump that used to accommodate a drive shaft. I'm not entirely clear whether the T will be under or behind the passenger seat. In any event, I don't suspect that folks will likely accuse them of under-engineering the battery pack housing.
    29 Mar 2010, 09:32 AM Reply Like
  • Advill
    , contributor
    Comments (2308) | Send Message
    In engineering design you try to avoid redundant designs, for example, if you have a metal carcass to surround a car, then you try to merge that into the chassis structure to avoid weight, volume and cost , so the cars migrated of having a frame AND a body into a concept of structural frame which is the car today.


    In batteries I assume that shield has many possible reasons as:


    Reducing vibrations into the batteries components
    Reducing noise into the passenger area from tunnel and front supports.
    Increasing structural body weight
    Reducing gravity center
    Safety design in case if impact or fire
    Reducing explosion hazard (your suggestion)


    there are some others which can be more related to marketing of the product as:


    "Selling" a compact concept
    Related regulations in other fields as aeronautic
    Simply, regulation over batteries whatever the chemistry it is...perhaps in Germany or Canada
    It easier to sell a concept "modular" THAT A BUNCH OF BOXES AND CABLES.


    If you open a laptop battery carcass you will find a bunch of cylindrical small ion lithium batts in a "no high tech" fashion.


    Resuming....many reasons can be behind the GM design....


    29 Mar 2010, 10:53 AM Reply Like
  • Mark Divy
    , contributor
    Comments (214) | Send Message
    Concur that there are many possible reasons, but I would bet that if they are running this down the old drive shaft hump - then some of this shielding is to protect the occupants from the heat transfer? Might make folks jittery if they could feel the heat generated during the battery use through the floor...


    Not sure why they would want to create a hump in the passenger area if not required. Over engineered the battery case, but not the occupant area.
    29 Mar 2010, 11:02 AM Reply Like
  • Advill
    , contributor
    Comments (2308) | Send Message
    A problem of batteries AND engine is that batteries are bulky and usually rest storage space in the trunk, most drivers are used to the central tunnel (there are many front wheel cars designs that still use it just as a duct to cables and hoses), BMW,Daimler, etc still use it.


    I assume that GM is using this idea to spare trunk space.


    29 Mar 2010, 11:40 AM Reply Like
  • scuilla
    , contributor
    Comments (2) | Send Message
    When engineers design a system they usually take from their own experience base that has proven some level of achievement. Check out the profile of the EV1 battery - it is T-shaped.


    Boeing did the same thing with the Dreamliner battery - unfortunately they were wrong. Lithium technology is not like Nicad technology. They did have some warning signs but did nothing.
    28 Aug 2013, 09:10 AM Reply Like
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