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5417Re: [evworld] Re: Batteries

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  • Yodda Pierce
    Oct 9, 2005
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      I just wanted to answer your last question here.
      Perhaps your question was rhetorical, but you asked
      what applications would require 3000 Wh/Kg. My
      thought would be like military vehicles like tanks,
      amphibious assault vehicles, aircraft, commercial and
      military, perhaps trucks. Those are a few I can think
      of. The advantage would be if we had a battery with
      this type of energy, fuel cells would not be needed
      due to their high cost. Then all the resources could
      focus on batteries and the result would be to get a
      high output EV batery available to the public. The
      problem right now seems not to be that we do not have
      a battery that meet the criteria for electric
      vehicles, but rather that the cost for such a battery
      pack is very expensive making the electric vehicle
      50-100% more than the cost of the ICE vehicle.
      Therefore, additional resources need to be spent not
      only to improve battery technology, but rather to
      improve production methodologies to make these
      advanced battery chemistries affordable in a EV pack.
      The lowest cost I could find for a 30 Kwh battery pack
      was from a company called Thunder Sky in China. It
      was about $15,000-20,000 which was a decrease of
      $80,000 from the $100,000 price tag for a similar
      lithium polymer battery from 3M. Hopefully we can see
      the prices fall to $1000-$5000 range in the future and
      we can then see the BEV become very close to the price
      of the ICE car and have similar range. Of course new
      battery technologes still need to be considered,
      however we are now in th e position where existing
      technology can produce a low weight, high power output
      EV battery pack. We just need to get the price down.

      --- Paul Scott <pscottvfx@...> wrote:

      > Hi All,
      > I'm enjoying the talk about batteries. Yes, it's the
      > crux of the matter. A
      > while back, I asked a question to the EV lists about
      > the theoretical limits
      > to batteries. I got several great responses, but
      > William Kortoff's seemed to
      > be the best. I'm reprinting it below:
      > At 07:30 PM 3/29/2004, Paul Scott wrote:
      > A question for you engineers on the lists. This is
      > a quote from "Power To
      > the People" by Vijay Waitheeswaran in a section on
      > the battery electric
      > vehicle:
      > "The trouble is that battery systems are pushing
      > the upper limits of
      > specific energy - the number of watt-hours they can
      > store for a given
      > weight. The best that conventional batteries can
      > achieve theoretically is
      > 300 watt-hours per kilogram (Wh/kg), though most
      > manage barely half that in
      > practice. That is nowhere near enough for the armed
      > forces. The Pentagon has
      > said that it wants to deploy portable equipment
      > loaded with energy-guzzling
      > features that would require up to 3100 Wh/kg by
      > 2006. The physical
      > properties of batteries make it impossible for them
      > to ever achieve such
      > goals."
      > His comments on the needs of the military
      > notwithstanding, are his facts
      > and figures correct on the battery's theoretical
      > limit? I had not heard of
      > such a limit and he doesn't explain it at all.
      > Paul Scott
      > 310-399-5997
      > pscottvfx@...
      > This does remind me of gloom and doom
      > anti-technology predictions from
      > the past. It is possible to know and calculate the
      > theoretical maximum
      > energy from specific battery combinations---that's
      > basic electrochemistry.
      > The theoretical limits of current batteries are
      > actually much higher than
      > 300 wh/kg. The basic reactants of lead acid imply a
      > limit around 120
      > watt hours per kilogram, and actual batteries
      > deliver 20 to 40 wh/kg.
      > At the other extreme, I believe the reactants of
      > current lithium battery
      > chemistries imply a theoretical value around
      > 1500-3000 wh/kg. The
      > difference between the theoretical and actual values
      > results from the
      > weight of case, electrical conductors, separators,
      > electrolyte, important
      > non-reactant ingredients, and reactants that don't
      > get used.
      > Fifteen years ago, the best practical and known
      > rechargeable batteries
      > delivered maybe 70 wh/kg. Today, commercial
      > batteries are reaching
      > 200 wh/kg. It is fair to argue on a technical basis
      > that a specific
      > chemistry will have a definite practical performance
      > limit. But new
      > combinations will continue to be developed in the
      > future; I wouldn't
      > want to predict where things will go in the future.
      > I certainly wouldn't
      > want to predict that technology won't improve beyond
      > a certain point.
      > I can't see what practical applications would need
      > 3000 wh/kg.
      > /wk
      > > All good points Ernie. To look at electric
      > vehicles today, one would think
      > > they all have
      > > to be small and extremely ugly. Also looking at
      > hybrids and plug-in
      > > hybrids gives the
      > > impression that we will always have an internal
      > combustion engine in our
      > > vehicle. But
      > > predicting the future can make everyone look
      > silly.
      > >
      > > For now, the plug-in hybrid looks like the best
      > "vehicle" to blaze the
      > > trail to a pure
      > > electric vehicle. Biofuels definitely fit well
      > with a plug in hybrid and
      > > hopefully we
      > > will see both these technologies blossom soon.
      > With the history of battery
      > > electric
      > > vehicles, it's easy to understand why they seem
      > limited to small marginal
      > > units. But
      > > every single limitation of the battery electric
      > vehicle that I've been
      > > able to think of,
      > > all leads back to the battery. The next question
      > one must ask oneself is,
      > > has battery
      > > technology already reached its zenith. If we
      > listen to General Motors and
      > > others, this is
      > > the case. They claim that they've given up on the
      > battery and have moved
      > > on to the
      > > hydrogen fuel cell. What they actually claim is
      > that they've given up on
      > > the electric
      > > vehicle, but we all know a hydrogen fuel cell
      > vehicle is nothing but an
      > > electric vehicle
      > > that gets its electricity from the fuel cell.
      > >
      > > Possibly the battery has run up against a
      > technological brick wall.
      > > Possibly General
      > > Motors is being genuine and does not have a hidden
      > agenda in their
      > > campaign to explain to
      > > us why they have given up on the battery electric
      > vehicle. But while
      > > General Motors and
      > > US Car may have given up, others still have some
      > hope for the battery. My
      > > belief is that
      > > battery technology is still in its infancy.
      > Materials science along with
      > > growing need
      > > from all sectors of society may still produce some
      > very pleasant and
      > > exciting battery
      > > technology surprises for us in the future.
      > >
      > > Why should a battery be any different than the gas
      > tank? Why can't a
      > > battery be superior
      > > to a fuel tank? If the battery can be recharged in
      > about the same amount
      > > of time it takes
      > > to fill the fuel tank, that eliminates one of the
      > biggest gripes. If the
      > > battery can be
      > > made to work in all weather conditions, another
      > common gripe goes by the
      > > wayside. And if
      > > range can be achieved similar to that of liquid
      > fuel vehicles, no one will
      > > have that to
      > > complain about. There or still cost and
      > environmental and other issues to
      > > consider but I
      > > see no brick wall.
      > >
      > > Why couldn't a large truck be a pure battery
      > vehicle? What, other than our
      > > current
      > > perceptions or misperceptions makes something like
      > this impossible. It's
      > > tough to twist
      > > our minds in new ways and as we predict the future
      > were sure to look like
      > > fools at times.
      > > There is also a lot of inertia to break through,
      > as with any new concept.
      > > The electric
      > > vehicle is generally understood to have certain
      > characteristics. Even
      > > people who are
      > > usually up on the latest technologies and are
      > knowledgeable about vehicles
      > > in particular
      > > will often hold some very incorrect views about
      > electric vehicles. Battery
      > > electric
      > > trucks may still be a long way off but the view of
      > all electric vehicles
      > > as being slugs
      > > on the road is about to be shattered.
      === message truncated ===

      Yahoo! Mail - PC Magazine Editors' Choice 2005
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