Comments on: The Electric Engine..and questions http://gm-volt.com/2007/01/12/the-electric-engineand-questions/ Real-time news, information, and discussion about the Chevrolet Volt. Thu, 11 Mar 2010 18:23:52 +0000 http://wordpress.org/?v=2.9.1 hourly 1 By: Roger http://gm-volt.com/2007/01/12/the-electric-engineand-questions/#comment-111705 Roger Wed, 06 May 2009 14:28:14 +0000 http://www.gm-volt.com/?p=6#comment-111705 Hello, I found your blog in a new directory of blogs. I dont know how your blog came up, must have been a typo, but Im glad it came out ;) Hello, I found your blog in a new directory of blogs. I dont know how your blog came up, must have been a typo, but Im glad it came out ;)

]]> By: Pete http://gm-volt.com/2007/01/12/the-electric-engineand-questions/#comment-5785 Pete Sat, 01 Sep 2007 14:47:29 +0000 http://www.gm-volt.com/?p=6#comment-5785 Robert, think in kW and kWh for these puppies. Electric motors are very efficient - 90% is number that I have seen used. Then the numbers begin to make sense. For example, a Volt, at 3,000 lbs. will require about 1/5 kWh delivered to the wheels to accelerate to 60 miles. At 60 mph, the Volt, likely similar to the Prius, should experience an aerodynamic drag of about 8 kW and a rolling resistance of 4 kW. So, on flat ground, at 60 mph, the Volt would consume 1/5 kWh per minute during which time it travels one mile. This equates to 8.2 kWh plus about 10% for electrical system inefficiencies for a total of about 9 kWh for 40 miles. At 30 mph, the drag is 1/8 that at 60 mph and the rolling resistance is halved and the volt would consume 1/20 kWh per min, or 1/10 kWh per mile. This equates to 4.6 kWh for 40 miles. An average 1% grade over the 40 miles would change the power requirements by 3.6 and 1.8 kW at 60 and 30 mph, respectively, and change the energy usage by 2.65 kWh in both cases. The effect of this altitude change has contaminated the Tesla Roadster's range demonstration where it was driven from Lake Tahoe to Tesla'a offices, a drop of several thousand feet with a gain of 5 kWh or so. Robert, think in kW and kWh for these puppies. Electric motors are very efficient – 90% is number that I have seen used. Then the numbers begin to make sense.

For example, a Volt, at 3,000 lbs. will require about 1/5 kWh delivered to the wheels to accelerate to 60 miles. At 60 mph, the Volt, likely similar to the Prius, should experience an aerodynamic drag of about 8 kW and a rolling resistance of 4 kW. So, on flat ground, at 60 mph, the Volt would consume 1/5 kWh per minute during which time it travels one mile. This equates to 8.2 kWh plus about 10% for electrical system inefficiencies for a total of about 9 kWh for 40 miles.

At 30 mph, the drag is 1/8 that at 60 mph and the rolling resistance is halved and the volt would consume 1/20 kWh per min, or 1/10 kWh per mile. This equates to 4.6 kWh for 40 miles.

An average 1% grade over the 40 miles would change the power requirements by 3.6 and 1.8 kW at 60 and 30 mph, respectively, and change the energy usage by 2.65 kWh in both cases. The effect of this altitude change has contaminated the Tesla Roadster’s range demonstration where it was driven from Lake Tahoe to Tesla’a offices, a drop of several thousand feet with a gain of 5 kWh or so.

]]> By: Robert Cole http://gm-volt.com/2007/01/12/the-electric-engineand-questions/#comment-3766 Robert Cole Sat, 11 Aug 2007 11:56:38 +0000 http://www.gm-volt.com/?p=6#comment-3766 The numbers do not add up. A standard wall outlet will deliver approx. 20 KWHs worth of juice during a full 12 hour re-charging cycle. This will only power a 160 HP motor for about 15 minutes assuming on average it will be 1/3 loaded and all the juice for acceleration is recovered during braking. This is hardly enough time to drive 40 miles unless perhaps you are puttering down a country road at 40 MPH at 1/5 load in no traffic, with no AC or lights on and make no stops. I love the idea of a peppy flashy car that plugs in at night and can go 40 miles on the batteries alone but the physics here do not add up. The numbers do not add up. A standard wall outlet will deliver approx. 20 KWHs worth of juice during a full 12 hour re-charging cycle. This will only power a 160 HP motor for about 15 minutes assuming on average it will be 1/3 loaded and all the juice for acceleration is recovered during braking.

This is hardly enough time to drive 40 miles unless perhaps you are puttering down a country road at 40 MPH at 1/5 load in no traffic, with no AC or lights on and make no stops. I love the idea of a peppy flashy car that plugs in at night and can go 40 miles on the batteries alone but the physics here do not add up.

]]> By: A. meadows http://gm-volt.com/2007/01/12/the-electric-engineand-questions/#comment-177 A. meadows Tue, 20 Feb 2007 01:13:12 +0000 http://www.gm-volt.com/?p=6#comment-177 I think if a car company comes out with a electric car with a charge capacity that will last at lease 125 miles will become no.1 in Canada and beat out all japanese or korean cars.I know I would choose GM again if they sold a good electric commuter car. I think if a car company comes out with a electric car with a charge capacity that will last at lease 125 miles will become no.1 in Canada and beat out all japanese or korean cars.I know I would choose GM again if they sold a good electric commuter car.

]]> By: chevyvolt http://gm-volt.com/2007/01/12/the-electric-engineand-questions/#comment-76 chevyvolt Fri, 09 Feb 2007 17:09:43 +0000 http://www.gm-volt.com/?p=6#comment-76 Hi Herman, Welcome to our site and thanks for the compliment! Also thanks for the firsthand information. We are extremely interested in the battery. Do you know if the current prototype is able to perform at the posted specs, or is still a work in progress? Hi Herman,
Welcome to our site and thanks for the compliment!
Also thanks for the firsthand information.
We are extremely interested in the battery.
Do you know if the current prototype is able to perform at the posted specs, or is still a work in progress?

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