Comments on: USABC Battery Contractor Comparison http://gm-volt.com/2007/10/27/usabc-battery-contractor-comparison/ Real-time news, information, and discussion about the Chevrolet Volt. Mon, 13 Feb 2012 03:11:06 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: GM-VOLT : Chevy Volt Concept Site » Compact Power CEO Describes How Their New Chevy Volt Cells are Better http://gm-volt.com/2007/10/27/usabc-battery-contractor-comparison/#comment-17839 GM-VOLT : Chevy Volt Concept Site » Compact Power CEO Describes How Their New Chevy Volt Cells are Better Wed, 05 Dec 2007 14:51:12 +0000 http://www.gm-volt.com/2007/10/27/usabc-battery-contractor-comparison/#comment-17839 [...] For more on how some battery companies lithium-ion cells compare with one another, see this post: (LINK) [...] [...] For more on how some battery companies lithium-ion cells compare with one another, see this post: (LINK) [...]

]]> By: AES http://gm-volt.com/2007/10/27/usabc-battery-contractor-comparison/#comment-12579 AES Mon, 29 Oct 2007 07:50:20 +0000 http://www.gm-volt.com/2007/10/27/usabc-battery-contractor-comparison/#comment-12579 [quote comment="12537"]The motor is 120KW; to generate that power with a 160kg pack you would only need a power density of 750w/kg.[/quote] Very true. However, the more powerful the cells are, the lower the discharge rate needs to be to achieve 120kW. The lower the discharge rate, the less strain it is on the battery, and the longer the lifespan. [quote comment="12537"]The motor is 120KW; to generate that power with a 160kg pack you would only need a power density of 750w/kg.[/quote]

Very true. However, the more powerful the cells are, the lower the discharge rate needs to be to achieve 120kW. The lower the discharge rate, the less strain it is on the battery, and the longer the lifespan.

]]> By: Mike756 http://gm-volt.com/2007/10/27/usabc-battery-contractor-comparison/#comment-12537 Mike756 Mon, 29 Oct 2007 01:51:50 +0000 http://www.gm-volt.com/2007/10/27/usabc-battery-contractor-comparison/#comment-12537 Having specific power less than 3000W/kg doesn't seem like a problem. The energy density is much more limiting, but still very good. Assuming 100wh/kg, you would need 160kg battery for the 16kwh pack. The motor is 120KW; to generate that power with a 160kg pack you would only need a power density of 750w/kg. Having specific power less than 3000W/kg doesn’t seem like a problem. The energy density is much more limiting, but still very good. Assuming 100wh/kg, you would need 160kg battery for the 16kwh pack. The motor is 120KW; to generate that power with a 160kg pack you would only need a power density of 750w/kg.

]]> By: AES http://gm-volt.com/2007/10/27/usabc-battery-contractor-comparison/#comment-12515 AES Sun, 28 Oct 2007 21:53:51 +0000 http://www.gm-volt.com/2007/10/27/usabc-battery-contractor-comparison/#comment-12515 [quote comment="12482"]Until they start delivering the Volt or go public with specifics on each cell then it is all guess work.[/quote] Yes but given that the automotive A123 cells are made with the same fundamental chemistry, you can at least do some EDUCATED guesswork. For example, part of the power density of the power tool (M1) cells is that there is a short path length from the electrode to the current collector. If you were to thicken the electrodes, the path from electrode to current collector is longer, and there is more electrical resistance in the way. This reduces the power, but would also increase the amount of energy storage. Given the premium put on weight reduction and energy storage, the Volt will probably make this compromise. In other words, expect a specific power lower than 3,000W (~4 horsepower) per kilogram of batteries, but do expect specific energy closer to LiFePO4's theoretical max energy storage of ~130Wh/kg. [quote comment="12482"]Until they start delivering the Volt or go public with specifics on each cell then it is all guess work.[/quote]

Yes but given that the automotive A123 cells are made with the same fundamental chemistry, you can at least do some EDUCATED guesswork.

For example, part of the power density of the power tool (M1) cells is that there is a short path length from the electrode to the current collector. If you were to thicken the electrodes, the path from electrode to current collector is longer, and there is more electrical resistance in the way. This reduces the power, but would also increase the amount of energy storage.

Given the premium put on weight reduction and energy storage, the Volt will probably make this compromise.

In other words, expect a specific power lower than 3,000W (~4 horsepower) per kilogram of batteries, but do expect specific energy closer to LiFePO4′s theoretical max energy storage of ~130Wh/kg.

]]> By: Van http://gm-volt.com/2007/10/27/usabc-battery-contractor-comparison/#comment-12499 Van Sun, 28 Oct 2007 18:25:27 +0000 http://www.gm-volt.com/2007/10/27/usabc-battery-contractor-comparison/#comment-12499 Guesswork sounds dismissive, how about feasibility estimate. Guesswork sounds dismissive, how about feasibility estimate.

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