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Re: EV kits on S.F.Craigslist
by Peter VanDerWal
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There range figures are very questionable. I'd be inclined to say BS.
60 miles at 55mp with a 72V pack of GC batteries?
This isn't like 1970's technology, it IS 1970's technology. Specifically
it's a guy that has a large stockpile of equipment that is 30 years old
and he's trying to sell it for way to much.
For only about 10% more you can do a conversion that uses modern
components and will work with a normal conversion, not a fiberglass kit on
a VW pan.
> cowtown@... wrote:
>> An 800A contactor and "Regen braking with down shifting" and
>> "remanufactured and modified jet fighter plane generator used as
>> motor" sounds like an EV made in the 70's that avoids using that same
>> era's more silicon-heavy controls (SCRs, Triodes, etc). Any idea how
>> smoothly a VW-with-jet-starter/generator conversion can be driven in
>> everyday use, how efficiently they run when compared to current motors
>> and PWM controllers, and what is their comparative durability?
>
> The 1970's aircraft starter-generators are still state-of-the-art today;
> DC motor technology has hardly moved. They have huge strong commutators,
> class H insulation, interpoles and pole facing windings, high speed
> bearings, are banded and balanced for high RPM, etc. They are excellent
> for regenerative braking.
>
> However, they were optimized to be light, not efficient. Compared to a
> modern series DC traction motor, The aircraft starter-generator is about
> half the weight but only 75% efficient versus 85%. They also didn't care
> about noise; these things scream like a giant vacuum cleaner.
>
> Smoothness isn't a characteristic of the motor; it's a characteristic of
> the controller.
>
>> Would a "cutting-edge' Curtis SepEx controller, say 600A in the 36-84V
>> range, make this older style conversion any more efficient, or would
>> it also need a motor more specific to the job?
>
> If the old one used an SCR controller, a Curtis or other modern
> controller will be more efficient. The efficiency of the motor itself
> won't change.
>
> The main limitations of these old unit are:
>
> - lower efficiency (reduces range by 10% or so)
> - hard to use shaft (odd spines, no support bearing)
> - need a lot of cooling (due to lower efficiency, no internal fan)
> - too small for a full-size EV (only suited to very small light cars)
> --
> Ring the bells that still can ring
> Forget the perfect offering
> There is a crack in everything
> That's how the light gets in -- Leonard Cohen
> --
> Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
>
_______________________________________________
For subscription options, see
http://lists.sjsu.edu/mailman/listinfo/ev
60 miles at 55mp with a 72V pack of GC batteries?
This isn't like 1970's technology, it IS 1970's technology. Specifically
it's a guy that has a large stockpile of equipment that is 30 years old
and he's trying to sell it for way to much.
For only about 10% more you can do a conversion that uses modern
components and will work with a normal conversion, not a fiberglass kit on
a VW pan.
> cowtown@... wrote:
>> An 800A contactor and "Regen braking with down shifting" and
>> "remanufactured and modified jet fighter plane generator used as
>> motor" sounds like an EV made in the 70's that avoids using that same
>> era's more silicon-heavy controls (SCRs, Triodes, etc). Any idea how
>> smoothly a VW-with-jet-starter/generator conversion can be driven in
>> everyday use, how efficiently they run when compared to current motors
>> and PWM controllers, and what is their comparative durability?
>
> The 1970's aircraft starter-generators are still state-of-the-art today;
> DC motor technology has hardly moved. They have huge strong commutators,
> class H insulation, interpoles and pole facing windings, high speed
> bearings, are banded and balanced for high RPM, etc. They are excellent
> for regenerative braking.
>
> However, they were optimized to be light, not efficient. Compared to a
> modern series DC traction motor, The aircraft starter-generator is about
> half the weight but only 75% efficient versus 85%. They also didn't care
> about noise; these things scream like a giant vacuum cleaner.
>
> Smoothness isn't a characteristic of the motor; it's a characteristic of
> the controller.
>
>> Would a "cutting-edge' Curtis SepEx controller, say 600A in the 36-84V
>> range, make this older style conversion any more efficient, or would
>> it also need a motor more specific to the job?
>
> If the old one used an SCR controller, a Curtis or other modern
> controller will be more efficient. The efficiency of the motor itself
> won't change.
>
> The main limitations of these old unit are:
>
> - lower efficiency (reduces range by 10% or so)
> - hard to use shaft (odd spines, no support bearing)
> - need a lot of cooling (due to lower efficiency, no internal fan)
> - too small for a full-size EV (only suited to very small light cars)
> --
> Ring the bells that still can ring
> Forget the perfect offering
> There is a crack in everything
> That's how the light gets in -- Leonard Cohen
> --
> Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
>
_______________________________________________
For subscription options, see
http://lists.sjsu.edu/mailman/listinfo/ev
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