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EVcast #196: The Porsche Kinda-EV-But-Not-Really

Friday, March 13th 2009 @ 2:16 PM (not yet rated)    post viewed 4766 times

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Jeffrey Ulshafer
Free Access
DuaL85 said on Saturday, March 14th 2009 @ 4:49 AM:

Two 110 Vac plugs connected on both outlet ports on a standard 110 volt 15/20 ampere duplex receptacle will NOT increase voltage to 220 volts and will NOT allow you to charge any quicker. With circuit conductors (110v charger cords) configured in parallel, you would only double the ampacity (current carrying limit) of the charging cables. Example: Two conductors are rated at 15 amperes each. Wiring these conductors in parallel allows the circuit to carry 30 amperes given the proper conditions (proper overcurrent  size, feeders, etc). A special 220 volt "two" phase (A,B) outlet will be required to accomplish faster charge times. Notice A and B. All residential circuits begin at the transformer atop a nearby utility pole. Inside that transformer are winding sets and each set has loops of wire wound around an iron inner core to increase permeability (ability to conduct mag flux). When configuring both winding sets in series, enough magnetism soaks in to induce 240 volts alternating current across the core into both wound wire sets. The addition of more than one leg (phase) enables you to obtain voltage (240vac) above standard 110 vac. Bottom line: If you plug into a standard 110 volt receptacle only one of the phase wires (A) are present, making it impossible to get the other phase (B) for 240 volts. 110 electric outlets are designed to accept one phase only (A or B) but never both. Remember: Higher voltage always means lower current (amperes) with resistance (ohms) constant. Lower current means less heat, less power loss (I^2*R), and smaller conductors.

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John Briggs
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JohnBriggs said on Saturday, March 14th 2009 @ 7:59 AM:

Dual85 is correct.

If two wires are connected to the car, but lead to the same circuit breaker in your house,  no additional power is available.

However, if you brought one of the wires to a different outlet, on a different circuit breaker, additional power is available.

  This got me to thinking about my own garage.  I have a 120v/15a outlet in the garage.  So this is 1800 watts.  However, whenever the garage door opener is pressed, it takes 600 watts.  So the full 1800 watts is not available to charge an EV.  We can only use 1200 watts for charging an EV.

   Does anyone know how much wattage the Telsa uses when charging on a 120V outlet?

    If other people's houses are like mine, I suspect they will need to have an electrician run an additional line to their garage to power their EV.  At that point, they might as well run a 240V line.

Later
John C. Briggs

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Hasbro
Free Access
Hasbro said on Saturday, March 14th 2009 @ 5:44 PM:

John,

That was the direction I was heading.  I posted on the live chat, assuming your coming from different outlets and yes on different circut breakers also.  In my home I have outlets in the garage but also had them wire me up two extra outlets, one for a freezer and I think I have another the builder put in for a sprinkler system.  I know the freezer has its own breaker and maybe also the sprinkler not to mention the standard outlets in the garage.  So I was on the line of thinking if people have outlets in the garage or nearby on different circuts then if the auto companys add a second charging port on the car and we know that these batteries are just a bunch of cells chained together, why can't one outlet charge a portion of the battery the another handles the rest thereby decreasing overall charging time.

I figured it would only help in the addoption of EV's and would not add an extra burden of buyers to have to modify their homes.  Yes a small mod of course.

I'm sure car companies have thought of this so there is probably a good reason they haven't done it.

Hasbro

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John Briggs
Free Access
JohnBriggs said on Sunday, March 15th 2009 @ 8:41 AM:

Hasbro,

    I find the discussion interesting.

    Occasionally, we hear people saying we need a "new infrastructure for electric vehicles."  My reaction is usually, the cool thing about electricity is that we already have the infrastruture.  We are seldom very far from an outlet.  So why do we need "new infrastruture".

    The reality seems to be more complicated.

    Yes, there are electrical outlets everywhere.  However, they supply only a small amount of power.  So if we use these "standard outlets" that might already be powering other devices, the charging times will be long.

    Perhaps we will need slightly better infrastructure to facilitate EV charging.  The existing infrastructure is good to get started with EV'S, but we will need bigger pipes over time.

Later
John C. Briggs

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Bo Bennett
Tuesday Host
Group Administrator
Bo said on Sunday, March 15th 2009 @ 8:47 AM:

Think about the Internet.  Most people these days have broadband which allows for a great Internet experience - thanks to a much improved infrastructure over the last 15 years.  However, 15 years ago the Internet was launched with the "current infrastructure" of phone lines.  It did the job and launched the technology.  It was far from ideal, but did the trick.  We will adapt and grow.  We always do.

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Hasbro
Free Access
Hasbro said on Sunday, March 15th 2009 @ 11:13 AM:

Bo,

Interestingly enough most highspeed internet today comes via the cable tv outlet in most older homes.  It's just plain ole copper wiring.  And people are using power over ethernet to network their homes instead of CAT5 in older homes.  Of course fiber is the new standard but it is interesting how technology intended for one purpose is being used for another.

Hasbro

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John Briggs
Free Access
JohnBriggs said on Sunday, March 15th 2009 @ 12:14 PM:

Bo,
    Good points.

     I think new infrastructure will be needed with EVs over time.  But we can get started today.

     This is very different from hydrogen powered cars that really have a "chicken and egg" problem.

Later
John C. Briggs

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John Briggs
Free Access
JohnBriggs said on Sunday, March 15th 2009 @ 12:19 PM:

Well,
   I thought our weakened economy would have significantly cut down on our electricity usage, but I guess I was wrong.

    US Generation

Dec 2007     346,290 gigawatthours

Dec 2008     341,732 gigawatthours

or only a 1.3% decrease. So I guess global economic collapse cannot fix global warming.

   Well, I guess no matter how bad the economic crisis is, American's cannot seem to remember to turn off the lights.

Later
John C. Briggs

Data: eia.doe.gov  Monthly Flash Estimates of Electric Power Data, December 2008

 

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John Briggs
Free Access
JohnBriggs said on Monday, March 16th 2009 @ 1:22 PM:

 

Apropro of nothing

If you created a Tesla battery pack (53KWH) out of different battery technologies, how much would it weigh.  Here is what I found.

 

battery size 53 KWH

battery type Density   Density    Weight   Weight
                     (MJ/kg)     KWH/kg       kg         lbs
Gasoline         46.4          12.889          4           9
Li Ion               0.54          0.150       353      777
NiMH                0.25          0.069       763    1679
Lead Acid         0.09           0.025     2120    4664

http://en.wikipedia.org/wiki/Energy_density

So, you can see how cool gasoline is.  Very lightweight.

You can also see how terrible Lead-Acid is.

 

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John Briggs
Free Access
JohnBriggs said on Monday, March 16th 2009 @ 1:55 PM:

Standard EV connector J1772

http://www.sae.org/dlymagazineimages/5889_5641_ART.jpg

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Rick Covert
Free Access
RickCovert said on Monday, March 16th 2009 @ 6:01 PM:

John,

I have a beautiful graph that perfectly illustrates your energy density comparisons between gasoline, LiOn (sorry no NiMH) and lead acid heading your way. It demonstrates quite clearly that the adoption of gasoline vehicles was no conspiracy unless you accept the conspiracy of the laws of thermodynamics.

Rick,

From the oil capital of the world, Houston, TX Laughing

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John Briggs
Free Access
JohnBriggs said on Monday, March 16th 2009 @ 7:39 PM:

Rick,
   Beautiful graphic, but it is not to scale.  If it was to scale, you wouldn't even be able to see the batteries.
    EV's are cool, but you have to give credit where it is due.  Gasoline has excellent energy density.
Later
John C. Briggs

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