# [EVDL] Zenn Says See You Later, Batteries!



## EVDL List (Jul 27, 2007)

>From the ET list. Lawrence Rhodes.....
Posted by: "Remy Chevalier" [email protected] cleannewworld
Date: Sun Sep 2, 2007 9:50 am ((PDT))

Startup Says See You Later, Batteries!
Breakthrough Power Technology Claims to Deliver 500 Miles on 5-Minute Charge
By GRANT SLATER
AUSTIN, Texas -- Aug. 31, 2007-

http://abcnews.go.com/Technology/Story?id=3D3547157&page=3D1


Millions of inventions pass quietly through the U.S. patent office each
year. Patent No. 7,033,406 did, too, until energy insiders spotted six words
in the filing that sounded like a death knell for the internal combustion
engine.

An Austin-based startup called EEStor promised "technologies for replacement
of electrochemical batteries," meaning a motorist could plug in a car for
five minutes and drive 500 miles roundtrip between Dallas and Houston
without gasoline.

By contrast, some plug-in hybrids on the horizon would require motorists to
charge their cars in a wall outlet overnight and promise only 50 miles of
gasoline-free commute. And the popular hybrids on the road today still
depend heavily on fossil fuels.

"It's a paradigm shift," said Ian Clifford, chief executive of Toronto-based
ZENN Motor Co., which has licensed EEStor's invention. "The Achilles' heel
to the electric car industry has been energy storage. By all rights, this
would make internal combustion engines unnecessary."

Clifford's company bought rights to EEStor's technology in August 2005 and
expects EEStor to start shipping the battery replacement later this year for
use in ZENN Motor's short-range, low-speed vehicles.

The technology also could help invigorate the renewable-energy sector by
providing efficient, lightning-fast storage for solar power, or, on a small
scale, a flash-charge for cell phones and laptops.

Skeptics, though, fear the claims stretch the bounds of existing technology
to the point of alchemy.

"We've been trying to make this type of thing for 20 years and no one has
been able to do it," said Robert Hebner, director of the University of Texas
Center for Electromechanics. "Depending on who you believe, they're at or
beyond the limit of what is possible."

EEStor's secret ingredient is a material sandwiched between thousands of
wafer-thin metal sheets, like a series of foil-and-paper gum wrappers
stacked on top of each other. Charged particles stick to the metal sheets
and move quickly across EEStor's proprietary material.


The result is an ultracapacitor, a battery-like device that stores and
releases energy quickly.

Batteries rely on chemical reactions to store energy but can take hours to
charge and release energy. The simplest capacitors found in computers and
radios hold less energy but can charge or discharge instantly.
Ultracapacitors take the best of both, stacking capacitors to increase
capacity while maintaining the speed of simple capacitors.

Hebner said vehicles require bursts of energy to accelerate, a task better
suited for capacitors than batteries.

"The idea of getting rid of the batteries and putting in capacitors is to
get more power back and get it back faster," Hebner said.

But he said nothing close to EEStor's claim exists today.

For years, EEStor has tried to fly beneath the radar in the competitive
industry for alternative energy, content with a yellow-page listing for an
indiscriminate office building and a handful of cryptic press releases.

Yet the speculation and skepticism have continued, fueled by the company's
original assertion of making batteries obsolete - a claim that still
resonates loudly for a company that rarely speaks, including declining an
interview with The Associated Press.

The deal with ZENN Motor and a $3 million investment by the venture capital
group Kleiner Perkins Caufield & Byers, which made big-payoff early bets on
companies like Google Inc. and Amazon.com Inc., hint that EEStor may be on
the edge of a breakthrough technology, a "game changer" as Clifford put it.

ZENN Motor's public reports show that it so far has invested $3.8 million in
and has promised another $1.2 million if the ultracapacitor company meets a
third-party testing standard and then delivers a product.

Clifford said his company consulted experts and did a "tremendous amount of
due diligence" on EEStor's innovation. EEStor's founders have a track
record. Richard D. Weir and Carl Nelson worked on disk-storage technology at
IBM Corp. in the 1990s before forming EEStor in 2001. The two have acquired
dozens of patents over two decades.

Neil Dikeman of Jane Capital Partners, an investor in clean technologies,
said the nearly $7 million investment in EEStor pales compared with other
energy storage endeavors, where investment has averaged $50 million to $100
million.

Yet curiosity is unusually high, Dikeman said, thanks to the investment by a
prominent venture capital group and EEStor's secretive nature.

"The EEStor claims are around a process that would be quite revolutionary if
they can make it work," Dikeman said. Previous attempts to improve
ultracapacitors have focused on improving the metal sheets by increasing the
surface area where charges can attach.

EEStor is instead creating better nonconductive material for use between the
metal sheets, using a chemical compound called barium titanate. The question
is whether the company can mass-produce it.

ZENN Motor pays EEStor for passing milestones in the production process, and
chemical researchers say the strength and functionality of this material is
the only thing standing between EEStor and the holy grail of energy-storage
technology.

Joseph Perry and the other researchers he oversees at Georgia Tech have used
the same material to double the amount of energy a capacitor can hold. Perry
says EEstor seems to be claiming an improvement of more than 400-fold, yet
increasing a capacitor's retention ability often results in decreased
strength of the materials.

"They're not saying a lot about how they're making these things," Perry
said. "With these materials (described in the patent), that is a challenging
process to carry out in a defect-free fashion."

Perry is not alone in his doubts. An ultracapacitor industry leader, Maxwell
Technologies Inc., has kept a wary eye on EEStor's claims and offers a
laundry list of things that could go wrong.

Among other things, the ultracapacitors described in EEStor's patent operate
at extremely high voltage, 10 times greater than those Maxwell manufactures,
and won't work with regular wall outlets, said Maxwell spokesman Mike Sund.
He said capacitors could crack while bouncing down the road, or slowly
discharge after a dayslong stint in the airport parking lot, leaving the
driver stranded.

Until EEStor produces a final product, Perry said he joins energy
professionals and enthusiasts alike in waiting to see if the company can own
up to its six-word promise and banish the battery to recycling bins around
the world.

"I am skeptical but I'd be very happy to be proved wrong," Perry said.



Copyright =A9 2007 ABC News Internet Ventures

Messages in this topic (1)

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## EVDL List (Jul 27, 2007)

I'd like to see a line drawn representing it's rate of discharge.
Because I doubt it's linear in the sense it goes from 3500 V to 0 like
this: \ Or even less of an angle. It might be flat then drop off
suddenly and rapidly at some point? Isn't that how capacitors usually
discharge?

Any progress on the 3500 V Zilla Otmar?  Still at 2,000 amps or so?

How hard is it going to be to make a controller of sorts for this 3500 V device?

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## EVDL List (Jul 27, 2007)

My favorite part:

"a motorist could plug in a car for five minutes and drive 500 miles 
roundtrip between Dallas and Houston
without gasoline."

Let's see, 500 miles in an NEV...
How about Dallas to Houston in a LSV...

> Startup Says See You Later, Batteries!
> Breakthrough Power Technology Claims to Deliver 500 Miles on 5-Minute 
> Charge
> By GRANT SLATER
> AUSTIN, Texas -- Aug. 31, 2007-
>http://abcnews.go.com/Technology/Story?id=3547157&page=1



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## EVDL List (Jul 27, 2007)

Well yeah if you can hook straight up to the feeder lines coming out of
a nuclear power plant, maybe a 5 min change could happen with enough
cooling.

Danny

----- Original Message -----
From: Adrian DeLeon <[email protected]>
Date: Monday, September 3, 2007 2:34 pm
Subject: Re: [EVDL] Zenn Says See You Later, Batteries!
To: [email protected]

> My favorite part:
> 
> "a motorist could plug in a car for five minutes and drive 500 
> miles 
> roundtrip between Dallas and Houston
> without gasoline."
> 
> Let's see, 500 miles in an NEV...
> How about Dallas to Houston in a LSV...
> 
> > Startup Says See You Later, Batteries!
> > Breakthrough Power Technology Claims to Deliver 500 Miles on 5-
> Minute 
> > Charge
> > By GRANT SLATER
> > AUSTIN, Texas -- Aug. 31, 2007-
> >http://abcnews.go.com/Technology/Story?id=3547157&page=1
> 
> 

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## EVDL List (Jul 27, 2007)

Old story by now, search the archives.
EEStor has nothing to prove their claims yet, but neither is there any
evidence that they will not be able to deliver something useful.

They've made some remarkable ultracaps in the past IIRC, not useful for
powering an EV but still quite a remarkable advancement suggesting they
do indeed have a cutting edge technology base there.

Danny

----- Original Message -----
From: Lawrence Rhodes <[email protected]>
Date: Monday, September 3, 2007 12:08 pm
Subject: [EVDL] Zenn Says See You Later, Batteries!
To: Electric Vehicle Discussion List <[email protected]>,
[email protected], [email protected]

> >From the ET list. Lawrence Rhodes.....
> Posted by: "Remy Chevalier" [email protected] =

> cleannewworld Date: Sun Sep 2, 2007 9:50 am ((PDT))
> =

> Startup Says See You Later, Batteries!
> Breakthrough Power Technology Claims to Deliver 500 Miles on 5-
> Minute Charge
> By GRANT SLATER
> AUSTIN, Texas -- Aug. 31, 2007-
> =

> http://abcnews.go.com/Technology/Story?id=3D3547157&page=3D1
> =

> =

> Millions of inventions pass quietly through the U.S. patent office =

> eachyear. Patent No. 7,033,406 did, too, until energy insiders =

> spotted six words
> in the filing that sounded like a death knell for the internal =

> combustionengine.
> =

> An Austin-based startup called EEStor promised "technologies for =

> replacementof electrochemical batteries," meaning a motorist could =

> plug in a car for
> five minutes and drive 500 miles roundtrip between Dallas and Houston
> without gasoline.
> =

> By contrast, some plug-in hybrids on the horizon would require =

> motorists to
> charge their cars in a wall outlet overnight and promise only 50 =

> miles of
> gasoline-free commute. And the popular hybrids on the road today still
> depend heavily on fossil fuels.
> =

> "It's a paradigm shift," said Ian Clifford, chief executive of =

> Toronto-based
> ZENN Motor Co., which has licensed EEStor's invention. "The =

> Achilles' heel
> to the electric car industry has been energy storage. By all =

> rights, this
> would make internal combustion engines unnecessary."
> =

> Clifford's company bought rights to EEStor's technology in August =

> 2005 and
> expects EEStor to start shipping the battery replacement later this =

> year for
> use in ZENN Motor's short-range, low-speed vehicles.
> =

> The technology also could help invigorate the renewable-energy =

> sector by
> providing efficient, lightning-fast storage for solar power, or, on =

> a small
> scale, a flash-charge for cell phones and laptops.
> =

> Skeptics, though, fear the claims stretch the bounds of existing =

> technologyto the point of alchemy.
> =

> "We've been trying to make this type of thing for 20 years and no =

> one has
> been able to do it," said Robert Hebner, director of the University =

> of Texas
> Center for Electromechanics. "Depending on who you believe, they're =

> at or
> beyond the limit of what is possible."
> =

> EEStor's secret ingredient is a material sandwiched between =

> thousands of
> wafer-thin metal sheets, like a series of foil-and-paper gum wrappers
> stacked on top of each other. Charged particles stick to the metal =

> sheetsand move quickly across EEStor's proprietary material.
> =

> =

> The result is an ultracapacitor, a battery-like device that stores and
> releases energy quickly.
> =

> Batteries rely on chemical reactions to store energy but can take =

> hours to
> charge and release energy. The simplest capacitors found in =

> computers and
> radios hold less energy but can charge or discharge instantly.
> Ultracapacitors take the best of both, stacking capacitors to increase
> capacity while maintaining the speed of simple capacitors.
> =

> Hebner said vehicles require bursts of energy to accelerate, a task =

> bettersuited for capacitors than batteries.
> =

> "The idea of getting rid of the batteries and putting in capacitors =

> is to
> get more power back and get it back faster," Hebner said.
> =

> But he said nothing close to EEStor's claim exists today.
> =

> For years, EEStor has tried to fly beneath the radar in the =

> competitiveindustry for alternative energy, content with a yellow-
> page listing for an
> indiscriminate office building and a handful of cryptic press =

> releases.
> Yet the speculation and skepticism have continued, fueled by the =

> company'soriginal assertion of making batteries obsolete - a claim =

> that still
> resonates loudly for a company that rarely speaks, including =

> declining an
> interview with The Associated Press.
> =

> The deal with ZENN Motor and a $3 million investment by the venture =

> capitalgroup Kleiner Perkins Caufield & Byers, which made big-
> payoff early bets on
> companies like Google Inc. and Amazon.com Inc., hint that EEStor =

> may be on
> the edge of a breakthrough technology, a "game changer" as Clifford =

> put it.
> =

> ZENN Motor's public reports show that it so far has invested $3.8 =

> million in
> and has promised another $1.2 million if the ultracapacitor company =

> meets a
> third-party testing standard and then delivers a product.
> =

> Clifford said his company consulted experts and did a "tremendous =

> amount of
> due diligence" on EEStor's innovation. EEStor's founders have a track
> record. Richard D. Weir and Carl Nelson worked on disk-storage =

> technology at
> IBM Corp. in the 1990s before forming EEStor in 2001. The two have =

> acquireddozens of patents over two decades.
> =

> Neil Dikeman of Jane Capital Partners, an investor in clean =

> technologies,said the nearly $7 million investment in EEStor pales =

> compared with other
> energy storage endeavors, where investment has averaged $50 million =

> to $100
> million.
> =

> Yet curiosity is unusually high, Dikeman said, thanks to the =

> investment by a
> prominent venture capital group and EEStor's secretive nature.
> =

> "The EEStor claims are around a process that would be quite =

> revolutionary if
> they can make it work," Dikeman said. Previous attempts to improve
> ultracapacitors have focused on improving the metal sheets by =

> increasing the
> surface area where charges can attach.
> =

> EEStor is instead creating better nonconductive material for use =

> between the
> metal sheets, using a chemical compound called barium titanate. The =

> questionis whether the company can mass-produce it.
> =

> ZENN Motor pays EEStor for passing milestones in the production =

> process, and
> chemical researchers say the strength and functionality of this =

> material is
> the only thing standing between EEStor and the holy grail of energy-
> storagetechnology.
> =

> Joseph Perry and the other researchers he oversees at Georgia Tech =

> have used
> the same material to double the amount of energy a capacitor can =

> hold. Perry
> says EEstor seems to be claiming an improvement of more than 400-
> fold, yet
> increasing a capacitor's retention ability often results in decreased
> strength of the materials.
> =

> "They're not saying a lot about how they're making these things," =

> Perrysaid. "With these materials (described in the patent), that is =

> a challenging
> process to carry out in a defect-free fashion."
> =

> Perry is not alone in his doubts. An ultracapacitor industry =

> leader, Maxwell
> Technologies Inc., has kept a wary eye on EEStor's claims and =

> offers a
> laundry list of things that could go wrong.
> =

> Among other things, the ultracapacitors described in EEStor's =

> patent operate
> at extremely high voltage, 10 times greater than those Maxwell =

> manufactures,and won't work with regular wall outlets, said Maxwell =

> spokesman Mike Sund.
> He said capacitors could crack while bouncing down the road, or slowly
> discharge after a dayslong stint in the airport parking lot, =

> leaving the
> driver stranded.
> =

> Until EEStor produces a final product, Perry said he joins energy
> professionals and enthusiasts alike in waiting to see if the =

> company can own
> up to its six-word promise and banish the battery to recycling bins =

> aroundthe world.
> =

> "I am skeptical but I'd be very happy to be proved wrong," Perry said.
> =

> =

> =

> Copyright =A9 2007 ABC News Internet Ventures
> =

> Messages in this topic (1)
> =

> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
> =


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## EVDL List (Jul 27, 2007)

----- Original Message ----- 
From: "Lawrence Rhodes" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>; 
<[email protected]>; <[email protected]>
Sent: Monday, September 03, 2007 1:06 PM
Subject: [EVDL] Zenn Says See You Later, Batteries!


>From the ET list. Lawrence Rhodes.....
Posted by: "Remy Chevalier" [email protected] cleannewworld
Date: Sun Sep 2, 2007 9:50 am ((PDT))

Startup Says See You Later, Batteries!
Breakthrough Power Technology Claims to Deliver 500 Miles on 5-Minute Charge
By GRANT SLATER
AUSTIN, Texas -- Aug. 31, 2007-

http://abcnews.go.com/Technology/Story?id=3547157&page=1


Millions of inventions pass quietly through the U.S. patent office each
year. Patent No. 7,033,406 did, too, until energy insiders spotted six words
in the filing that sounded like a death knell for the internal combustion
engine.
Hi EVerybody;

Gees! I HOPE so. OK, putting on my Old Fart cap here, been in an' out of 
the EV Cause for, lets see, 40 plus years. Boy have I scene lottsa 
Badd-eries claims come and go over the years. Still running the goodamn Led 
Acids, as was YEARS ago. My pockets arent /or were EVer very deep. Not 
wanting to rain on anybodies parade here, but I'll take the Missouri Tag's 
statement: "Show Me State" I'm in that state now, without EVer leaving 
Connecticut. Oh I hope these guys have something? What a revolution it would 
be. Not only cars, but trux, trains, lawnmowers, even CAMERAS that didn't 
chomp through C cells like a dead short!

Badd-eries, Crapaciters, I don't care. Get them OUT there BEFORE the oil 
Co's violate every trust law, and bury the technoplogy. Look what happened 
to "Our" Nmh's Building a better battery is easy enough, getting it to the 
American Sheeple will be the issue!

End of Rant

Bob, waiting ....still 

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## EVDL List (Jul 27, 2007)

There isn't any sort of proof for their claims, and they're claiming
some pretty crazy stuff. This is hundreds if not thousands of times
better than current capacitors. It would be like going straight from
lead-acid batteries to something 100x times better than Li-Ion; an
extremely remarkable leap. Besides that, they're extremely secretive,
not answering any questions, leading me to doubt their claims even
further.

That said, I really, really hope they actually can produce these capacitors.

Also, capacitors wouldn't be a swap-out replacement for batteries; a
regular controller like Zilla would absolutely hate capacitors,
because of their discharge cycle.

If you're drawing constant current, the discharge profile of a
capacitor is a line from the max voltage at full charge to 0V at
empty. That means to get full capacity from them, your controller has
to work on any voltage from 3500V to 0V. Of course, you have to choose
some reasonable lower cutoff point; you can't operate all the way down
to 0V. If you choose to cut off at 10% voltage, you only lose 1% of
capacity, so that isn't such a big deal.

Designing electronics/controllers that work at such high voltages is a
big deal, though. Even huge IGBT's usually only go up to 1200 or 2400
volts. In low quantities, IGBTs that are big enough would cost over
$1000 each, making controllers extremely expensive. Designing a
controller for this would be much harder than designing a Curtis or a
Zilla.

Of course, if the capacitors actually existed, the potential benefits
would probably push big companies to develop the required technology,
but economics would probably prevent home EV'ers from getting their
hands on an appropriate controller for quite a while.

-Morgan

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## EVDL List (Jul 27, 2007)

> Morgan LaMoore wrote:
> > This is hundreds if not thousands of times
> > better than current capacitors.
> I agree there is reason to be doubtful about EEStor. such devotion to
> ...


----------



## EVDL List (Jul 27, 2007)

> I agree there is reason to be doubtful about EEStor. such devotion to
> secrecy is a bad sign of their mentality. but it's not true that what
> they claim is that much better than existing caps. from memory it's
> something like 20 times better specific energy than Maxwell's super
> caps. not thousands or hundreds.

Woah, I didn't realize we had such good caps!

> it's not true either that caps are fundamentally problematic to use for
> controllers. even if it discharged the voltage linearly that would be ok
> for switchmode controllers. the hv zillas can operate in a good range of
> voltages as they are. a cap discharges as the squareroot iirc. at half
> voltage it's 75% depleted. that's workable. GM's Volt is planned to use
> only 50% capacity of its lithiums from 80% charge down to 30%. make no
> mistake about it, if they have what they claim and get it to us it would
> be a wet dream come true even at the somewhat problematic 3500v. it
> would be the rifle headshot at the already mortally wounded ICE. it
> would be dead before it hit the ground so to speak.

I'm not saying it won't work well; I'm just saying that it won't work
well with the technology currently available to home EV'ers. There's
no doubt that if it were available for sale, car makers would snatch
it up and quickly design controllers that work great with its
capacitive discharge curves and high voltages. I just think it would
be a while before you or I could build our own EV to use EEstor caps.
I guess that doesn't matter, though; it's more important that EV's
replace gas cars than that we can make our own EV's with EEstor.

It seems like almost everyone's sentiment is "I don't think it's real,
but I hope it is."

-Morgan LaMoore

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## EVDL List (Jul 27, 2007)

Maxwell Ultracaps are 5wh/kg, EEStor's proposal is 350wh/kg.
EEStor's 52KW-Hr proposed pack would be 336 lbs and essentially be a
range equivalent of about 4.5 gal of gasoline. There is no reason 2 or
4 could not be used other than cost and weight capacity of the frame.

Traditional controllers would not handle the high voltage in the EEStor
proposal. In fact there are not many readily available transistor
options for high current transistors in this voltage range. IGBTs have
handled up to 6KV, if you try to account for inductive spikes then even
that may not be enough. Even with just a 4KV transistor, there aren't
many readily available ones to build a controller capable of hundreds of
amps. The cost could be astronomical if you could even obtain the
parts. So, it is not a matter of simply modifying an existing design if
the transistor type, gate driver, current limiter, etc need to be
changed. That's entirely a start-again-from-scratch problem.

I doubt this will be possible with the familiar brushed DC motor at all.
The PWM does not lower the voltage, it only chops it, in this case
chops it into very short (like <3% duty!) high current 3500V pulses. 
The inductance of the motor lowers the current, but that does nothing to
change the fact that there's short 3500V pulses being applied across the
commutator bars. I suspect arcing will quickly destroy it. An external
LC filter in the controller could filter it to an average low voltage DC
but when you look at how big the inductor and capacitors need to be it
may not be practical to make a controller that actually lowers the
voltage this way.

Well there are plenty of possible solutions, but it's all beside the
point- EEStor's not available nor proven to be possible. Nor is it
worthwhile to keep analyzing their specs in the patent, there is no
telling if the power/energy per unit mass/volume, or cost will turn out
anything like what they hypothesized initially. It was totally
premature to give specs based on a theory with no physical data to back
it up.

EEStor announced a "milestone" of being able to produce the barium
titaniate powder with the purity required to base a production line on
(whatever that means). They said they'd be providing them for the 2007
ZENN vehicles- well it's Sept and they're still a no-show, AFAIK they
have yet to demonstrate a prototype as well, even a small piece of this
module that weighs only a kg would be FINE proof-of-concept prototype if
it could demonstrate hundreds of W-hr/kg. Easy to verify what it does. 

Right now we don't even need to see yet if it can last for an indefinite
number of cycles, operate in a consumer vehicle environment, and can be
made cheap. We just need to see a demonstration of this "hundreds of
wh/kg", that's the key question.

Danny

----- Original Message -----
From: Dan Frederiksen <[email protected]>
Date: Monday, September 3, 2007 7:49 pm
Subject: Re: [EVDL] Zenn Says See You Later, Batteries!
To: Electric Vehicle Discussion List <[email protected]>



> > Morgan LaMoore wrote:
> > > This is hundreds if not thousands of times
> > > better than current capacitors.
> > I agree there is reason to be doubtful about EEStor. such devotion
> ...


----------



## EVDL List (Jul 27, 2007)

> --- [email protected] wrote:
> 
> I doubt this will be possible with the familiar
> brushed DC motor at all.
> ...


----------



## EVDL List (Jul 27, 2007)

> > --- [email protected] wrote:
> > I doubt this will be possible with the familiar
> > brushed DC motor at all.
> > The PWM does not lower the voltage, it only chops it,
> ...


----------



## EVDL List (Jul 27, 2007)

> However, a huge inductor with at least 10 times the inductance of the
> motor might work (in series with the motor). With 10 times the
> inductance, the motor would only experience 10% of the voltage spike;
> the inductor would deal with the rest of the voltage swing. You don't
> even need the capacitor (of an LC filter); the car's/motor's
> mechanical inertia takes care of that part for you. The inductor will
> be somewhat expensive, though, and cores that big aren't
> mass-produced.

Oh, one other problem with my inductor idea: with more inductance,
you'd have even worse problems with voltage spike when you switch the
transistor. You'd need some huge snubber caps to compensate.

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## EVDL List (Jul 27, 2007)

> --- Morgan LaMoore <[email protected]> wrote:
> 
> > > --- David D. Nelson <[email protected]> wrote:
> > > The solution is simple. Just put a BIG variac in
> ...


----------



## EVDL List (Jul 27, 2007)

> > Variacs are for AC power, not DC. Also, that seems
> > like a really
> > inefficient/lossy/expensive system.
>
> Hence the  at the end of the line. <g>
>

Oops, sorry for missing that.

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## EVDL List (Jul 27, 2007)

A transformer is certainly one solution, even an autotransformer like a
variac. The only thing is that like you say it'd need to be a BIG
variac. Transformer windings capable of hundreds of amps is a huge
amount of copper. A core capable of tens of kw is huge too. Well we
could up the freq (we still need HV transistors for an inverter for the
Primary side) but skin effect limits on wire diameter, leakage, and core
losses also increase.

But yeah this illustrates the different thinking necessary when the
controller's task changes this much.

Danny

----- Original Message -----
From: "David D. Nelson" <[email protected]>
Date: Monday, September 3, 2007 10:30 pm
Subject: Re: [EVDL] Zenn Says See You Later, Batteries!
To: Electric Vehicle Discussion List <[email protected]>

> 


> > --- [email protected] wrote:
> >
> > I doubt this will be possible with the familiar
> > brushed DC motor at all.
> ...


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## EVDL List (Jul 27, 2007)

Just saying, you need to deliver 200A @ 100V to a motor, that's under 6A 
average current @ 3500V but in reality the controller's transistors will 
need to switch pulses of 200A, 3500V @ about 3% duty cycle. So the 
transistors need to be capable of peak currents of 200A, although the 
average still needs to be only 6A.

The inductance of the motor may not be enough to smooth out the current 
here. In fact with that low of a duty I'm pretty sure it won't be 
enough. An inductor's current changes in proportion to voltage, so 
current will change real fast during that 3% on-time. Of course it has 
to, 97% of the time it's running on the energy stored in the magnetic 
field alone and current will decay quite a bit over all that time unless 
you lower the period (raise the switching freq).

In regards to an LC filter output stage for the controller:
The inductance won't make an additional voltage spike because the 
flyback diode takes care of that. But what I think WILL happen is in a 
DC motor, the brief period between contacts on the commutator will 
result in an intense arc as the load is removed. By its nature this 
high voltage spike is in the same direction as the motor's normal 
voltage so you can't catch it with a diode. A cap can moderate it but a 
cap stage with hundreds of amps of ripple rating @ high voltage is 
really really expensive as well as large and failure-prone.

Danny



> Morgan LaMoore wrote:
> 
> >>--- [email protected] wrote:
> >>I doubt this will be possible with the familiar
> ...


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## EVDL List (Jul 27, 2007)

> > --- [email protected] <[email protected]> wrote:
> > A transformer is certainly one solution, even an autotransformer like a
> > variac. The only thing is that like you say it'd need to be a BIG
> > variac.
> ...


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## EVDL List (Jul 27, 2007)

> [email protected] wrote:
> > Maxwell Ultracaps are 5wh/kg, EEStor's proposal is 350wh/kg.
> 
> This is why I will doubt EEstor's claims until real samples are
> ...


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## EVDL List (Jul 27, 2007)

> [email protected] wrote:
> > A transformer is certainly one solution, even an autotransformer like a
> > variac. The only thing is that like you say it'd need to be a BIG
> > variac. Transformer windings capable of hundreds of amps is a huge
> ...


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## EVDL List (Jul 27, 2007)

I think the key to using this type of technology will be to hide it from
the user behind a dc-dc converter having it's own inductance and
capacitance.
A very high efficiency bidirectional dc-dc converter (QR-ZVS?) would
provide something like a 300V, -100 to 400 amp interface .
This can then feed an AC 3phase hbridge or a dc motor. Maybe the dc
link voltage would be controllable and be part of the control or maybe
it is just dumb, acts like a battery and lets us use whatever controller
we want. At 300:3500 we are already at 12:1 voltage ratio in the dc-dc.
That is pushing the limit on practical high power dc-dc converters,
especially if we are asking to have a dynamic range of 12:1 to 2:1

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## EVDL List (Jul 27, 2007)

> Jeff Shanab wrote:
> > A very high efficiency bidirectional dc-dc converter (QR-ZVS?) would
> > provide something like a 300V, -100 to 400 amp interface. This can
> > then feed an AC 3-phase h-bridge or a DC motor. Maybe the DC link
> ...


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## EVDL List (Jul 27, 2007)

> > At 300v:3500v we are already at 12:1 voltage ratio in the DC-DC.
> > That is pushing the limit on practical high power dc-dc converters,
> > especially if we are asking to have a dynamic range of 12:1 to 2:1
>
> Not really. Any PFC boost converter has a fixed output (about 400vdc)
> and an input that varies from 0v to the peak of the AC line (370v for a
> 240vac line). These are mass produced by the millions and have
> efficiencies of 95% or so.

Except that in a PFC boost converter, the power drawn is proportional
to the square of the input voltage, so there is low current at low
voltage. For an EV, you want constant power, so current is inversely
proportional to voltage. I suspect that this will have a big effect on
efficiency.

Also, we're talking much higher power here. How many 20kW wall
adapters do you see?

> Wide-range DC/DC step-down converters are also common. Universal input
> switching power supplies will deliver 12vdc with a 90-265vac input
> range, and there are many DC/DCs with a 4:1 input range. A 6:1 input
> range is a little more difficult, but straightforward.

Most of these are low current; an EV would need 100 times more
current, which means 10000 times more resistive losses. You don't
really want to use 10000 times more copper to make up for that.

-Morgan

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## EVDL List (Jul 27, 2007)

Lee Hart Wrote:
>Not really. Any PFC boost converter has a fixed output (about 400vdc)
and an input that varies from 0v to the peak of the AC line (370v for a
240vac line). These are >mass produced by the millions and have
efficiencies of 95% or so.

>Wide-range DC/DC step-down converters are also common. Universal input
switching power supplies will deliver 12vdc with a 90-265vac input
range, and there are >many DC/DCs with a 4:1 input range. A 6:1 input
range is a little more difficult, but straightforward.


I was thinking in terms of High Power and Bi-directional converters.
Since each side needs to be sized for the max current and max voltage it
can produce, Isn't their a inheriant loss of efficiency when some of the
active components are significantly oversized for the main mode of use?

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## EVDL List (Jul 27, 2007)

Lee Hart Wrote:
>> Any PFC boost converter has a fixed output (about 400vdc) and an
>> input that varies from 0v to the peak of the AC line (370v for a
>> 240vac line). These are mass produced by the millions and have
>> efficiencies of 95% or so.
>>
>> Wide-range DC/DC step-down converters are also common... there
>> are many DC/DC's with a 4:1 input range. A 6:1 input range
>> range is a little more difficult, but straightforward.



> Jeff Shanab wrote:
> > I was thinking in terms of High Power and Bi-directional converters.
> > Since each side needs to be sized for the max current and max voltage
> > it can produce, isn't their a inheriant loss of efficiency when some
> ...


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## EVDL List (Jul 27, 2007)

> Morgan LaMoore wrote:
> > Except that in a PFC boost converter, the power drawn is proportional
> > to the square of the input voltage, so there is low current at low
> > voltage.
> ...


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