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gfvalvo
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Iron
Re: Pretty Darn Real to Me
gfvalvo   8/5/2013 5:04:29 PM
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MIROX
User Rank
Platinum
Re: Pretty Darn Real to Me
MIROX   8/5/2013 4:53:57 PM
You need to explain this to EPA, DOE, NHTSA and SAE as all EV's are rated in MPGe, which is based on calculation of how many Watts  are consumed per mile traveled in the FTP 75 EPA test.

It is simply measured and calculated by kW/h meter that registers the power needed to recharge the batteries after they are at the point the OEM software stops the vehicle from further use.

The KW/h on the meter is then divided by the miles accumulated, and this is the W/mi that is then converted to MPGe.

Example:

Vehcile traveled 29.2 miles ( = 4 City cicles as each is about 7.3 miles) and needed 4.9 kW/h to recharge.

4900/29.2= 167W/mile

MPGe based on 33.7 kilowatt-hours per gallon

So 33700/167= 201MPGe

 

 

gfvalvo
User Rank
Iron
Re: Pretty Darn Real to Me
gfvalvo   8/5/2013 4:46:56 PM
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You can't use watts / hour or watts / mile because Watts are a unit of POWER (the rate at which energy is used ---- energy / unit time). You can use joules / hour or joules / mile because joules are a unit of ENERGY. BTW, watt-hours or kW-hours are also units of energy. But, as I said, watts are units of power.

MIROX
User Rank
Platinum
Re: Pretty Darn Real to Me
MIROX   8/5/2013 4:38:18 PM
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The example was that if car uses 250Watts per mile and travels at 60 Miles per Hour then it is the same as using 250 Watts per minute or 15kW/h

If you take 15,000 Wats per hour and divide it by the 60 miles traveled then you are back to 250W/mile.

A/C or Heater does not care if you are moving or standing still thus any Power use per distance is meaningless, thus the Watts per Hour. (or minute)

If you travel at highway speed then 3.2kW/h heater will use 3.2kW/h per 60 miles or 53 W/mile.

Get to real life in City average speed that includes waiting at intersections for green light and suddenly that becomes only 17 MPH average (Statistic by DOE for 2012 Urban average speeds over 24 hr period)

And now you are using 187Watts per mile to heat the car, and with good regen in stop and go traffic the power to move the car will be in 160W/mile range.

That is what I wanted to explain, that "accessories" can actually need MORE power than what is needed to propel the vehicle itself in such conditions.

 

 

 

 

trees
User Rank
Iron
Range Anxiety
trees   8/5/2013 4:18:24 PM
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The article misses the point. The planet is warming, with dire consequences coming soon. The reason is our burning of fossil fuels. Using fuel to obtain motion is not efficient. Average power plant efficienty is about 30%. Cars only get 30% when they are driving hard under load. The car average efficiency is more like 20%. But, we have enjoyed big cars and have been blind to the looming CO2 problem. So we still cling to the illusion that it is reasonable to buy a car for the worst case scenerio.

Consider the i-MiEV. It is a light weight (2500lb) mini car with no features, and a limited 62 mile range. But, it can be obtained for $12500 including taxes, after rebates. It gets 118mpg equivalent. Our grid has about 35% renewable (hydro and other). This makes it's fossil equivalent mpg at 181 mpg. Add solar pv to your house, and the car can be said to be running entirely on solar. Meanwhile the grid offers electricity at night for less than 4cents/KWH, and will pay for excess electricity to the grid at 34cents/KWH on summer afternoons. The grid cost of fuel drops to 1cent/mile from the grid.

  So getting a small cheap EV for most of your short in-town travel is very economical, and can eliminate CO2 generation for in-town use. If the EV car is cheap enough, then the bigger, heavier, low efficiency vehicle can be used for the exceptional long trip or big load. Then you are led to believe that the big vehicle might just as well be rented, or treated like an RV.  

Martin Benoît GAGNON, PHYS., ING.
User Rank
Iron
Egineer Job - A simple executing tech ?!?
Martin Benoît GAGNON, PHYS., ING.   8/5/2013 4:06:02 PM
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" Besides, it's the job of engineers to figure out what consumers want and then design to it. It's not the job of engineers to say, "Here's what you should want."

Here in Canada, and in almost countries where the profession of egineering is controled or ruled, the first role of engineers is the protection of the environnment, the safety and the well being of indiviudals.

Then Engineers can not considered themself as jsimple executing technician, but as professionnals, exercising their full professional judgment and with independency. This a legal obligation.

In consequence, this is a charge of engineers to correctly inform and teach people about technologies and their consequences, plus and minus, danger and false idea about them.

Ciao

Martin Benoît GAGNON, P.PHYS., ENG.

 

 

 

 

gfvalvo
User Rank
Iron
Re: Pretty Darn Real to Me
gfvalvo   8/5/2013 4:03:49 PM
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Watts are units of POWER (energy / unit time). Statements such as 250W per minute make no sense!!!

MIROX
User Rank
Platinum
Re: Depreciation
MIROX   8/5/2013 3:28:54 PM
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Prius is the most popular Hybrid, thus lot of them have been damaged in accidents especially in Southern California, and the range in EV mode is just few miles about 2 to 5.

So do not expect FIATe or HONDA Fit EV battery to be available for $1,500

VoltDave
User Rank
Iron
Re: Depreciation
VoltDave   8/5/2013 3:13:53 PM
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The Tesla Roadster was a low volume car, high price car.  More common EVs will have lower price options for battery repair or replacement.

Re-built Prius batteries are available for approximately $1,500.00. I wouldn't worry about an EV with a bad battery being "worthless."

MIROX
User Rank
Platinum
Re: Depreciation
MIROX   8/5/2013 3:05:28 PM
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If you are a business then even toady by IRS rules you can depreciate any vehicle used by business for business purposes to ZERO in 5 years.

If you are private owner then the long battery warranties of 8 to 10 years may be some sort of pacifier, but the fact is that average car on US roads is now over 11 years old, so for every NEW (age less than 1) car there is somewhere the "average" of a car that is 22 years old !!

I seriously doublt that the battery will be available at any price after the OEM warranty is over, and it will be the same case as with EV 1 - just crush them.

No company that currently sells EV has "retail price" that you can find for Battery pack, only "second hand" anecdotal evidence is available about TESLA Roadster pack that reportedly costs $50,000.

ICE has value as long as it runs, EV value is next to ZERO once the expensive battery is dead. Many Hybrids also will not function once the Traction battery is exhausted.

Solution ?

LEASE EV, (2 to 3 years) and do not even think of BUYING one !!!

 

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