Re: (ET) Re: new electrics

["David Roden (Akron OH USA)" <roden ald net>]

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
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