Re: (ET) Re: new electrics

[Dave & Debbie Barden <daveb seanet com>]

David were/are you a FORTRAN programmer  :)

dave 
seattle

> On 20 Feb 2004 at 22:08, Herb Crary wrote:
> 
> > My first comment is that using 12v instead of 36 volts means
> > that everything uses three times the current for the same power
> > level----wires, cables, switches, breakers, relays or contactors, etc. 
> > That
> > raises the cost, perhaps the space required, etc.
> 
> That was my first thought too.  But then I remembered the motor in the 
> 2004 
> Prius, which runs at a higher voltage than the previous model, even 
> though 
the 
> new model's battery pack is of a ^lower^ voltage.
> 
> Suppose the first thing your 12 volt battery sees is a boost converter 
> that 
> makes it into, say, 400 volts of AC.  Remember that if you're talking 
> lead 
> acid batteries (and you will be for cost reasons), you're going to need 
> lots 
> more than one of them (this has implications for the battery swapping 
> issue, 
> but we'll let that go for now).  So you have a converter for each 
> battery, 
> right there on those ^really big^ quick-connect terminals.  Maybe it's 
> even 
> part of the battery itself, and it can charge the battery when it's off 
> the 
> tractor.
> 
> Of course, now we have the additional cost of the converters.  We have 
> higher 
> voltage in the drive system, which means more safety concerns and 
> testing.  
> We're getting away from off the shelf parts, so development costs rise.  
> Everything has its price.
> 
> GE was smart to design the ET with off the shelf parts, many of them 
> golf car 
> components.  IMO, that's still the only way to build such a tractor at 
> an 
> affordable price - using existing components that already are in massive 
> serial production, though not necessarily golf car parts.
> 
> Inevitably, though we come back to the very substantial costs to develop 
> the 
> tractor, and the same old chicken and egg problem that's dogged (how 
> about 
> that for a mixed metaphor) EVs all along: 
> 
> while (no external factor stimulates demand) do {
> 
> You can't buy parts cheaply enough because you only need a small number;
> 
> You only need a small number because you'll only sell a few vehicles;
> 
> You'll only sell a few vehicles because the vehicle is so expensive; 
> 
> The vehicle is so expensive because you can't buy parts cheaply enough;
> 
> }
> 
> Ahem.
> 
> A very large company that is convinced of the long term profitability of 
> such 
> a machine could break out of that do loop by deciding that it will 
> absorb a 
> loss of, say, $1000 on each unit sold for the first 5 or 10 years.  If - 
> a 
big 
> IF - sales took off, they'd make it back up in the long term.  But large 
> companies today seldom look beyond the next quarter's results, because 
> their 
> investors demand immediate return.  I'm afraid that the era of 
> risk-taking 
> among US companies is mostly gone.
> 
> 
> David Roden - Akron, Ohio, USA
> 1991 Solectria Force 144vac
> 1991 Ford Escort Green/EV 128vdc
> 1970 GE Elec-trak E15 36vdc
> 1974 Avco New Idea 36vdc
> = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
> Open source software has fewer bugs because it admits the possibility
> of bugs.
> 
>                                       -- Napoleon
> 
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>      
> 
> 
> 
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