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Heavy Battery?

February 9th, 2007 | Posted in: Battery

A great new article written by Tony Whitney appeared in the Vancouver Sun. It can be viewed here.

The author seems to have some inside information on the battery and mentions that it is heavier than the goal battery for production. So it seems that not only do we have price, safety, lifetime, and temperature range issues, but we have a battery prototype that needs to go on a diet!

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Posted by: Lyle

2 Responses to “Heavy Battery?”


  1. Sky King Says:
    February 9th, 2007 at 1:59 pm

    Well I don’t see anything about batteries in that article - just another endless regurgitation of the same original 3 paragraph press release yada yada yada.


  2. Herman Says:
    February 12th, 2007 at 9:13 pm

    I can offer up some more thoughts on the battery. The original GM Volt battery concept may have used cells that were based on high power, charge sustaining battery packs, like those found in the Prius, or GM’s own BAS system. These have a power to energy ratio of about 15~18 and are less energy dense (about 40 Wh/kg for NiMH and about 80 Wh/kg for Li-ion). Hence, there may have been a comment from a GM rep about them being a bit overweight.
    The GM Volt is a mix between EV and HEV, and would benefit from a “custom” cell design that would tune the power to energy ratio to be about 10. That would help increase the energy density of the cells so that the weight bogey (about 160kg) becomes achievable with Lithium ion technology.
    The second challenge is that the power delivery must be satisfied over a wide range of SOC. A very demanding design challenge that necessitates a high performance lithium chemistry. Both A123/Cobasys and JCI/Saft have been mentioned as potential sources. Both companies have respectable chemistries with an eye toward nano particles and “flat” power delivery capability curves. This means that they don’t need to do “oversizing” to meet the Power vs. SOC challenge.
    The last set of challenges come from the life degradation issues and the low temperature issues.
    The real challenge may not be the weight, but the cost of a “new” high quality, large format battery. It’s not like you can go to the local BatteryMart and pick up some nice 80Ah Nano-Lithium cells for your Volt…

    Any one up for the challenge?

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