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The Volt's gasoline capacity is being cut back

The Chevy Volt plug-in electric car from GM is one of the most desired new cars coming to the market.  Everyone is talking about the car's stylish design and relatively affordable price tag of around $40,000; not bad compared to past electric cars totaling over $100,000 like the Tesla Roadster.  With sales planned to commence in 2010 and with a production model possibly being unveiled later this year, the buzz surrounding the new vehicle is intense.

One fact many people didn't know is that while the Volt is an electric car, relying first on charge, it also sports hybrid capabilities.  It features a 12 gallon gas tank, which will only kick in after the lithium-ion battery charge is depleted.  This could take the car 600 miles, thanks to an impressive 50 MPG projected fuel economy.

However, recent reports have revealed that GM, in a surprising development, has decided to cut down the fuel tank for the Volt.  They won't say what the new capacity will be, with the source only saying, "We're working on that." 

The original goal for the Volt was to equip it to drive 40 miles on a charge, without using any gas.  This goal remains, and appears to be within GM's reach.  Additionally, since 40 miles isn't long enough for road trips or longer business travels, GM planned on adding the gas tank.  The gas does not power a traditional engine, but rather a generator, which provides enough charge to keep going, and actually performs more efficiently than most gas-engines.

GM has revised the target range to 360 miles, which would seem to indicate a fuel tank of 7.2 gallons.  The reasoning behind the cut is research that cars, on average, travel less than 40 miles a day.  While GM wants to provide a comfortable extension to this range, it decided that 600 miles was a bit excessive.  Many older sedans don't get much more than 300 miles on a 12 gallon tank, so the new range seems relatively reasonable.

Jim Hossack, vice president of AutoPacific, an automotive research and consulting firm states, "Most cars today have a range of more than 300 miles and less than 400 miles before refueling.  GM didn't need a longer range because most bladders can't go 600 miles.  By going with a smaller tank it means GM can take weight and price out and make Volt a little lighter and a little cheaper, and that's what you call making an improvement."

While GM's move should help it cut costs and cut down slightly on the weight of the vehicle, it may come as a disappointment for fans of ultra-long treks across the country.  Still, it is dubious that such minor gripes will be able to do anything to quell the PR frenzy surrounding the Volt.

At its price tag, even with possible subsidies, the Volt will likely fall into the luxury car class.  However, with its wild popularity and sleek looks, it seems likely to thrive in this class, or whatever class it may enter as prices drop.



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RE: Hybrid
By jRaskell on 7/9/2008 3:39:53 PM , Rating: 2
First, Lithium Ion batteries are very efficient. Depending on the charging circuitry, anywhere from 96-99% efficient, so you lose VERY little efficiency going from electric to chemical back to electric.

Second, the Volt is designed to run directly off the ICE generator as much as possible once it switches to that mode of operation (which actually occurs when the battery drop below 30% charge). It'll only switch back to battery when the driver demands greater acceleration than the ICE generator can provide. The Volt has a 120kw electric drive motor (160hp) and a 53kw generator tied to the ICE. For any cruising or light throttle driving, the motor can easily be powered directly by the generator, with any surplus current being used to recharge the battery. It's only when hard acceleration is required that the motor falls back onto the battery.

So, all that power does NOT go through additional energy conversions to drive the car, and even what power does go through additional energy conversions, does so at a very high efficiency and still maintains a much higher overall efficiency than a standard direct drive ICE is capable of.


RE: Hybrid
By ChronoReverse on 7/9/2008 3:51:51 PM , Rating: 2
Wouldn't Toyota's HSD be the best of both worlds?

It uses a CVT with an Atkinson's Cycle engine in its drive, thus fulfilling the "running in the band" part of the equation. The HSD is capable of routing the gas engine output to either charge the batteries or to power the wheels (parallel hybrid).

The Prius is capable of running fully on electricity, fully on the gas engine or both at the same time depending on the situation and to varying degrees. If it had a better energy storage system (i.e., lithium ion batteries), it pretty much could run as a serial hybrid if that's the best choice for the situation.


RE: Hybrid
By pauldovi on 7/9/2008 4:31:26 PM , Rating: 2
The total peak charge efficiency is no where nere 99%. It may reach the upper 90% in ideal conditions, which means very slow charge, but it doesn't do that in the Volt's application. However, even at an unrealistic 96% charge / discharge efficiency, you are losing almost 8% of the energy. This also does not include the loss of energy from the conversion of mechanical energy to electrical energy in the generator.

What you are describing is a parallel hybrid system, and the Volt does not have this. The volt is driven soly by the electric motor (160HP) and the ICE is not connected to the powertrain. The ICE is only connected to the generator (71HP) and is completely independent of the powertrain. The car cannot be driven by the ICE and it cannot be driven by the electric motor connected to the ICE.

Any power generated by the ICE must first be converted from mechanical to electrical energy, then from electrical to chemical energy, then from chemical to electrical energy, then from electrical to mechanical energy. Unless of course the Volt is capable of bypassing the battery pack when it is depleted (this is unclear and seems like it is not by details on wikipedia).


RE: Hybrid
By jRaskell on 7/9/2008 5:52:20 PM , Rating: 2
Nothing about what I described is a parallel system.


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