DIY Electric Car Forums banner

1 - 20 of 22 Posts

·
Registered
Joined
·
70 Posts
Discussion Starter #1
Details and pictures of the prototype:

http://www.transport20.com/electric-vehicle/mitsubishi-i-miev-sport-brutally-fast-electric-sports-car-prototype/

--
Paul Wujek ([email protected])

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

·
Registered
Joined
·
70 Posts
Discussion Starter #2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 

·
Registered
Joined
·
70 Posts
Discussion Starter #3
> Details and pictures of the prototype:
>
> http://www.transport20.com/electric-vehicle/mitsubishi-i-miev-sport-brutally-fast-electric-sports-car-prototype/
>

Looks a little like the Loremo with more conventional layout (if you
can call it that!)

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

·
Registered
Joined
·
70 Posts
Discussion Starter #4
This looks like the output of a product design group who got together
and for a mutual masturbation session. I'm pretty sure no engineer
ever touched this.



On 10/25/07, Hunter Cook <[email protected]> wrote:
> Looks interesting. Most of it is pretty cool...I still don't know how to
> feel about hub motors (are they sprung?), but this bit is the only one
> that really got my eyebrows raised:
>
> "Someone at Mitsubishi has been really thinking outside the square in
> getting the most out of the vehicle because the car has several features
> we haven't seen before, including an auxiliary photovoltaic unit built
> into the roof, and a fan inside the front grill that generates
> electricity from the rush of air flow, both of which put energy back
> into the battery, just as the vehicle's regenerative braking also does."
>
> A FAN!? Please, tell me the reporter made that up as a joke.
>
> Hunter
>
> On Thu, 2007-10-25 at 23:09 +0000, Paul Wujek wrote:
> > Details and pictures of the prototype:
> >
> > http://www.transport20.com/electric-vehicle/mitsubishi-i-miev-sport-brutally-fast-electric-sports-car-prototype/
> >
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev


--
www.electric-lemon.com

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

·
Registered
Joined
·
70 Posts
Discussion Starter #5
All that work and they put the steering wheel on the wrong side. ;-)

On 10/26/07, Peter Gabrielsson <[email protected]> wrote:
> This looks like the output of a product design group who got together
> and for a mutual masturbation session. I'm pretty sure no engineer
> ever touched this.
>
>
>
> On 10/25/07, Hunter Cook <[email protected]> wrote:
> > Looks interesting. Most of it is pretty cool...I still don't know how to
> > feel about hub motors (are they sprung?), but this bit is the only one
> > that really got my eyebrows raised:
> >
> > "Someone at Mitsubishi has been really thinking outside the square in
> > getting the most out of the vehicle because the car has several features
> > we haven't seen before, including an auxiliary photovoltaic unit built
> > into the roof, and a fan inside the front grill that generates
> > electricity from the rush of air flow, both of which put energy back
> > into the battery, just as the vehicle's regenerative braking also does."
> >
> > A FAN!? Please, tell me the reporter made that up as a joke.
> >
> > Hunter
> >
> > On Thu, 2007-10-25 at 23:09 +0000, Paul Wujek wrote:
> > > Details and pictures of the prototype:
> > >
> > > http://www.transport20.com/electric-vehicle/mitsubishi-i-miev-sport-brutally-fast-electric-sports-car-prototype/
> > >
> >
> > _______________________________________________
> > For subscription options, see
> > http://lists.sjsu.edu/mailman/listinfo/ev
>
>
> --
> www.electric-lemon.com
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
>

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

·
Registered
Joined
·
70 Posts
Discussion Starter #6
Paul Wujek <[email protected]> wrote:
> Details and pictures of the prototype:
>
> http://www.transport20.com/electric-vehicle/mitsubishi-i-miev-sport-brutally-fast-electric-sports-car-prototype/

ABG has been covering the news on this
http://www.autobloggreen.com/category/mitsubishi/
Latest update:
The non-sport version available in Japan in small volume in 2009, at
$25K price point

There are a bunch of in-action videos available on this vehicle on YouTube
http://youtube.com/results?search_query=miev&search_sort=video_date_uploaded
This one, by EvWorld is particularly informative
http://youtube.com/watch?v=U3u-AdX_Mhc

-kert

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

·
Registered
Joined
·
70 Posts
Discussion Starter #7
Same reaction here.

What in heck does this mean?

"....and a fan inside the front grill that generates electricity from
the rush of air flow, both of which put energy back into the battery,
just as the vehicle's regenerative braking also does."

Hunter Cook <[email protected]> wrote:
> Looks interesting. Most of it is pretty cool...I still don't know how to
> feel about hub motors (are they sprung?), but this bit is the only one
> that really got my eyebrows raised:
>
> "Someone at Mitsubishi has been really thinking outside the square in
> getting the most out of the vehicle because the car has several features
> we haven't seen before, including an auxiliary photovoltaic unit built
> into the roof, and a fan inside the front grill that generates
> electricity from the rush of air flow, both of which put energy back
> into the battery, just as the vehicle's regenerative braking also does."
>
> A FAN!? Please, tell me the reporter made that up as a joke.
>
> Hunter
>
> On Thu, 2007-10-25 at 23:09 +0000, Paul Wujek wrote:
> > Details and pictures of the prototype:
> >
> > http://www.transport20.com/electric-vehicle/mitsubishi-i-miev-sport-brutally-fast-electric-sports-car-prototype/
> >
>
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev



--
Tehben
'90 Toyota 4x4 Pickup
'hElix EV'
Website: www.helixev.com
evalbum: http://www.austinev.org/evalbum/1225

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

·
Registered
Joined
·
70 Posts
Discussion Starter #8
It means some dodo over at Mitsubishi believes in perpetual motion machines.


----- Original Message ----

Same reaction here.

What in heck does this mean?

"....and a fan inside the front grill that generates electricity from
the rush of air flow, both of which put energy back into the battery,
just as the vehicle's regenerative braking also does."


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

·
Registered
Joined
·
70 Posts
Discussion Starter #9
Glenn Saunders <[email protected]> wrote:
> It means some dodo over at Mitsubishi believes in perpetual motion machines.
>
Or, it means its just a regular cooling fan and some reporter got a
bit confused.

-kert

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

·
Registered
Joined
·
70 Posts
Discussion Starter #10
If I understand this paragraph in the article correctly,
it means literally what it says. The fan behind grille generated
electricity. What's so weird about it?

I have fan behind radiator in my ACRX which has water cooled
drive. The fan could be positioned in front of the radiator,
makes no difference. It runs only when the temp of the inverter
heat sinks or motor windings exceeds preprogrammed value.

All other times it just sits there and I assume spins quite fast
from oncoming airflow at speed. The frontal area defines drag
resistance, if I have 1.5m^2 of the grill area and air comes in,
it will be certain wind resistance value and *almost* the same
whether that air just goes around under hood components and gets
drafted out, or does some useful work on the way (like spinning
that fan which is PM motor capable of generating some power, say,
to keep aux battery topped of, or even DC-DC'ed high enough
contribute to the traction battery. Contribution may seem small,
but otherwise power is just wasted, so you regain something
otherwise lost anyway. Similar to regen, and this has nothing to
do with perpetual motion - the fan is not on the roof where it would
indeed take more energy from the battery to run than it will produce.
It's already there, inside the car, and spins. I [almost] won't gain
efficiency by removing it - frontal area is not affected. So why
not take advantage of free generator?

If I would be interested to bother to
collect and measure energy generated by my fan, I'm sure I could
recover few Wh that way. Sure the cost of DC-DC and circuitry
making fan's role reversible may make it not worthwhile (for me),
but this is not the point of the article. It is very doable and
effect is measurable.

Victor

--
'91 ACRX - something different

Tehben Dean wrote:
> Same reaction here.
>
> What in heck does this mean?
>
> "....and a fan inside the front grill that generates electricity from
> the rush of air flow, both of which put energy back into the battery,
> just as the vehicle's regenerative braking also does."
>
>
Hunter Cook <[email protected]> wrote:
>> Looks interesting. Most of it is pretty cool...I still don't know how to
>> feel about hub motors (are they sprung?), but this bit is the only one
>> that really got my eyebrows raised:
>>
>> "Someone at Mitsubishi has been really thinking outside the square in
>> getting the most out of the vehicle because the car has several features
>> we haven't seen before, including an auxiliary photovoltaic unit built
>> into the roof, and a fan inside the front grill that generates
>> electricity from the rush of air flow, both of which put energy back
>> into the battery, just as the vehicle's regenerative braking also does."
>>
>> A FAN!? Please, tell me the reporter made that up as a joke.
>>
>> Hunter
>>
>> On Thu, 2007-10-25 at 23:09 +0000, Paul Wujek wrote:
>>> Details and pictures of the prototype:
>>>
>>> http://www.transport20.com/electric-vehicle/mitsubishi-i-miev-sport-brutally-fast-electric-sports-car-prototype/
>>>
>>
>> _______________________________________________
>> For subscription options, see
>> http://lists.sjsu.edu/mailman/listinfo/ev
>
>
>

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

·
Registered
Joined
·
70 Posts
Discussion Starter #11
----- Original Message -----
From: "Victor Tikhonov" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Friday, November 16, 2007 12:52 PM
Subject: Re: [EVDL] article: Mitsubishi i MiEV Sport - brutally fast
electric sports car prototype


> If I understand this paragraph in the article correctly,
> it means literally what it says. The fan behind grille generated
> electricity. What's so weird about it?

Absolutely nothing. If the fan serves a dual role (and it almost certainly
does) it makes complete sense. What truly is weird is the inability of some
list members to conceive of the possibility. I thought we were a pretty
smart bunch.

Lon

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

·
Registered
Joined
·
70 Posts
Discussion Starter #12
Victor Tikhonov <[email protected]> wrote:
> If I understand this paragraph in the article correctly,
> it means literally what it says. The fan behind grille generated
> electricity. What's so weird about it?
>
> from oncoming airflow at speed. The frontal area defines drag
> resistance, if I have 1.5m^2 of the grill area and air comes in,
The way i understand physics, the moment you connect a load (battery,
resistor or whatever ) to the generator behind the fan, your drag on
the fan increases.
Enough so that extra power put out by main motor due do this will be
bigger than power you get back.

-kert

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

·
Registered
Joined
·
70 Posts
Discussion Starter #13
I've been contemplating this also. I look at the two extremes:

If the wind blowing through the fan blade then slams into internal stuff and
slows down anyway, so you might think the drag would have been there anyway,
why not get something from it. But I figure it'll build back pressure back
to the fan blade, until there is little pressure drop across the blade, and
little energy converted to electricity by the blade. I don't think the
blade will recover much sitting in the middle of air stacked up in front of
the car, there will be no pressure differential to speak of, like a hydro
turbine in a dam with the same depth water on both sides.

If the airflow could be streamlined behind the fan blade so back pressure
wouldn't build behind the blade, then you'd be better off getting the fan
out of the way and letting the wind pass through, thus reducing aero drag.

I think the answer still comes up that if the fan is in good enough airflow
to recover significant energy, you're still better off letting the air pas
uninterrupted, so it's really just another perpetual motion example in
disguise. By definition, the fan can only recover power by increasing drag,
and it'll never be 100% efficient.

If the fan has to be there anyway for other uses, I suspect it would be
better to let it freewheel than load it with a generator that is less than
100% efficient and have it create more drag in the airflow.

Marty

----- Original Message -----
From: "Victor Tikhonov" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Friday, November 16, 2007 2:52 PM
Subject: Re: [EVDL] article: Mitsubishi i MiEV Sport - brutally fast
electric sports car prototype


> If I understand this paragraph in the article correctly,
> it means literally what it says. The fan behind grille generated
> electricity. What's so weird about it?
>
> I have fan behind radiator in my ACRX which has water cooled
> drive. The fan could be positioned in front of the radiator,
> makes no difference. It runs only when the temp of the inverter
> heat sinks or motor windings exceeds preprogrammed value.
>
> All other times it just sits there and I assume spins quite fast
> from oncoming airflow at speed. The frontal area defines drag
> resistance, if I have 1.5m^2 of the grill area and air comes in,
> it will be certain wind resistance value and *almost* the same
> whether that air just goes around under hood components and gets
> drafted out, or does some useful work on the way (like spinning
> that fan which is PM motor capable of generating some power, say,
> to keep aux battery topped of, or even DC-DC'ed high enough
> contribute to the traction battery. Contribution may seem small,
> but otherwise power is just wasted, so you regain something
> otherwise lost anyway. Similar to regen, and this has nothing to
> do with perpetual motion - the fan is not on the roof where it would
> indeed take more energy from the battery to run than it will produce.
> It's already there, inside the car, and spins. I [almost] won't gain
> efficiency by removing it - frontal area is not affected. So why
> not take advantage of free generator?
>
> If I would be interested to bother to
> collect and measure energy generated by my fan, I'm sure I could
> recover few Wh that way. Sure the cost of DC-DC and circuitry
> making fan's role reversible may make it not worthwhile (for me),
> but this is not the point of the article. It is very doable and
> effect is measurable.
>
> Victor
>
> --
> '91 ACRX - something different
>
> Tehben Dean wrote:
>> Same reaction here.
>>
>> What in heck does this mean?
>>
>> "....and a fan inside the front grill that generates electricity from
>> the rush of air flow, both of which put energy back into the battery,
>> just as the vehicle's regenerative braking also does."
>>
>>
Hunter Cook <[email protected]> wrote:
>>> Looks interesting. Most of it is pretty cool...I still don't know how to
>>> feel about hub motors (are they sprung?), but this bit is the only one
>>> that really got my eyebrows raised:
>>>
>>> "Someone at Mitsubishi has been really thinking outside the square in
>>> getting the most out of the vehicle because the car has several features
>>> we haven't seen before, including an auxiliary photovoltaic unit built
>>> into the roof, and a fan inside the front grill that generates
>>> electricity from the rush of air flow, both of which put energy back
>>> into the battery, just as the vehicle's regenerative braking also does."
>>>
>>> A FAN!? Please, tell me the reporter made that up as a joke.
>>>
>>> Hunter
>>>
>>> On Thu, 2007-10-25 at 23:09 +0000, Paul Wujek wrote:
>>>> Details and pictures of the prototype:
>>>>
>>>> http://www.transport20.com/electric-vehicle/mitsubishi-i-miev-sport-brutally-fast-electric-sports-car-prototype/
>>>>
>>>
>>> _______________________________________________
>>> For subscription options, see
>>> http://lists.sjsu.edu/mailman/listinfo/ev
>>
>>
>>
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
>
>


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

·
Registered
Joined
·
70 Posts
Discussion Starter #14
> The way i understand physics, the moment you connect a load (battery,
> resistor or whatever ) to the generator behind the fan, your drag on
> the fan increases.
> Enough so that extra power put out by main motor due do this will be
> bigger than power you get back.
>
> -kert

Yeah, the drag on the fan increases. The point is that the fan isn't
out in the open, it's inside the grill of the car where there's
already other stuff around it creating drag. The fan is already in a
turbulent airflow; you won't make a noticeable difference between
having it loaded and not loaded.

That said, it's probably not worth the effort/time/money unless it's a
dual-purpose cooling/generation fan (to cool the electronics at low
speeds, for example) or if it's just a marketing trick.

-Morgan LaMoore

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

·
Registered
Joined
·
70 Posts
Discussion Starter #15
From: Victor Tikhonov
>> If I understand this paragraph in the article correctly, it means
>> literally what it says. The fan behind grille generated
>> electricity. What's so weird about it?

Loni wrote:
> Absolutely nothing. If the fan serves a dual role (and it almost
> certainly does) it makes complete sense. What truly is weird is the
> inability of some list members to conceive of the possibility. I
> thought we were a pretty smart bunch.

A fan can indeed generate electricity if you let the wind spin it. But
the voltage it generates will be pretty low -- try it for yourself!

So, they would need a special DC/DC step-up converter to make use of
this power for (say) charging the 12v battery.

The next problem is in how much power you actually generate. If the
motor draws 12v at 10 amps as a fan (120 watts), it would be
exceptionally well designed if it could generate even 1/4th of that as a
wind generator. With the usual automotive grade motors and fans, even
1/10th of that (12 watts) would be doing good. Is it worth the bother to
generate 12 watts?

--
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
 

·
Registered
Joined
·
70 Posts
Discussion Starter #16
I can't explain it more clearly than I did. Just do the measurements
and you will see if this works.

Besides, I don't believe Mitsubishi engineers who created this EV
are complete idiots who is ignorant of such basic concepts of
physics. They would not do it it this would make no sense
(that is unless press grossly misinterpreted in the article what
they've actually done).

Victor

Marty Hewes wrote:
> I've been contemplating this also. I look at the two extremes:
>
> If the wind blowing through the fan blade then slams into internal stuff and
> slows down anyway, so you might think the drag would have been there anyway,
...
>
> If the fan has to be there anyway for other uses, I suspect it would be
> better to let it freewheel than load it with a generator that is less than
> 100% efficient and have it create more drag in the airflow.
>
> Marty
>

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

·
Registered
Joined
·
70 Posts
Discussion Starter #17
Lee Hart wrote:

> A fan can indeed generate electricity if you let the wind spin it. But
> the voltage it generates will be pretty low -- try it for yourself!

That of course depends on design. I'd try it if I had *that* particular
fan with its motor from *that* Mitsubishi.

> So, they would need a special DC/DC step-up converter to make use of
> this power for (say) charging the 12v battery.

If it's a plain DC motor driven fan (which is big assumption), fan
voltage will be proportional to its RPM. Meaning that spinning fast it
will always exceed 12VD output, in turn meaning that if it's directly
connected to a 12V battery ('course through the reverse diode to prevent
being powered from it) there will always be the balance point starting
at high enough veh. speed when that fan will be loaded on the battery
and current will flow in to it slowing it down, so the output drops
allowing speed up, and eventually self-sustained equilibrium will
be established.

> The next problem is in how much power you actually generate. If the
> motor draws 12v at 10 amps as a fan (120 watts), it would be
> exceptionally well designed if it could generate even 1/4th of that as a
> wind generator. With the usual automotive grade motors and fans,...

What makes you think that in this hi tech show-case EV usual automotive
grade motors and fans are used?

... even 1/10th of that (12 watts) would be doing good. Is it worth the
bother to
> generate 12 watts?
>
If it cost one diode and otherwise you loose that 12 watts anyway,
yes, it worth it. Why not?

If its DC-DC converter cost $1,000, no, it's not worth
it for you and me. But it worth it for Mitsubishi if someone decides to
buy this car for many thousands of dollars once they read (if true) that
engineers squeezed every drop of efficiency they could and something
[like this] in this car is so unique no other car has. They don't only sell
extra 12W, but bragging rights to point this out as achievement worthy
mentioning (which will be translated in money, they know it).

But, again, I'd take even 12W if it cost next to nothing and
otherwise is power lost anyway. I'm sure *their* fan, special
and optimized for this role output more than that though.

Victor

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

·
Registered
Joined
·
70 Posts
Discussion Starter #18
A fiend of mine has a bit of a spread including his own personal
junkyard in the high desert outside Ellensburg in central Washington
State. Once during a visit with him I conducted a bit of an
experiment.
The Ellensburg area is notorious for high winds (among other
things). I had been helping my friend sort through some piles of junk
that were lying around and had come across a small permanent-magnet
fan of the sort that plugs into a car's cigarette lighter. I removed
the shroud, attached the fan to a pole, and drove the pole into the
ground (I mean, the dirt, not the electrical ground ;) I then attached
my digital VOM to the fan's leads and let it sit. I did not have a
vane or other means to keep the fan pointed into the wind, and the
records I kept of the voltage readings are long gone, but IIRC I got a
mean of approximately 8 volts with peaks around 15. My WAG estimate of
the wind speed is 25 - 40 mph (gusty).
I reckon this is somewhat in line with the volume of air that
would travel across the fan(s) in question, but of course I can't
know for sure. The fan I used is almost certainly of lower quality /
efficiency than that used in the Mitsubishi, which would always be
pointed into the wind. The power produced would certainly not go very
far in keeping even an accessory battery charged, but as Victor points
out, if it is cheap enough- why not?

Victor Tikhonov <[email protected]> wrote:
> Lee Hart wrote:
>
> > A fan can indeed generate electricity if you let the wind spin it. But
> > the voltage it generates will be pretty low -- try it for yourself!
>
> That of course depends on design. I'd try it if I had *that* particular
> fan with its motor from *that* Mitsubishi.
>
> > So, they would need a special DC/DC step-up converter to make use of
> > this power for (say) charging the 12v battery.
>
> If it's a plain DC motor driven fan (which is big assumption), fan
> voltage will be proportional to its RPM. Meaning that spinning fast it
> will always exceed 12VD output, in turn meaning that if it's directly
> connected to a 12V battery ('course through the reverse diode to prevent
> being powered from it) there will always be the balance point starting
> at high enough veh. speed when that fan will be loaded on the battery
> and current will flow in to it slowing it down, so the output drops
> allowing speed up, and eventually self-sustained equilibrium will
> be established.
>
> > The next problem is in how much power you actually generate. If the
> > motor draws 12v at 10 amps as a fan (120 watts), it would be
> > exceptionally well designed if it could generate even 1/4th of that as a
> > wind generator. With the usual automotive grade motors and fans,...
>
> What makes you think that in this hi tech show-case EV usual automotive
> grade motors and fans are used?
>
> ... even 1/10th of that (12 watts) would be doing good. Is it worth the
> bother to
> > generate 12 watts?
> >
> If it cost one diode and otherwise you loose that 12 watts anyway,
> yes, it worth it. Why not?
>
> If its DC-DC converter cost $1,000, no, it's not worth
> it for you and me. But it worth it for Mitsubishi if someone decides to
> buy this car for many thousands of dollars once they read (if true) that
> engineers squeezed every drop of efficiency they could and something
> [like this] in this car is so unique no other car has. They don't only sell
> extra 12W, but bragging rights to point this out as achievement worthy
> mentioning (which will be translated in money, they know it).
>
> But, again, I'd take even 12W if it cost next to nothing and
> otherwise is power lost anyway. I'm sure *their* fan, special
> and optimized for this role output more than that though.
>
> Victor
>
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
>

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

·
Registered
Joined
·
70 Posts
Discussion Starter #19
> But, again, I'd take even 12W if it cost next to nothing and
> otherwise is power lost anyway. I'm sure *their* fan, special
> and optimized for this role output more than that though.
>
> Victor

I dont think people quite got this concept. The "power" is not lost
anyway, this power isnt even generated _unless_ you connect the load
to the generator.
Freewheeling fan is not generating power, it has voltage on generator
but there is no power, zero current, zero power.
As soon as you connect the load, the fan starts generating power,
taking this out of the airstream surrounding it. This airstream, in
normal EV is generated by main propulsion motor.
As soon as you try to get that power out of the airstream, youe either
have to increase power on main motor to maintain constant speed, or
your speed will reduce.

Its a small effect, and might go unnoticeable on your main wattmeter,
but regardless of that this remains true: extra power put out by main
motor will be bigger than power got back from the generator.
Regardless of where the fan is placed, external or internal, what type
of generator is connected and so on.

As with Mitsu MiEV, the article is a misinterpretation. ( Look at the
MiEV videos on youtube, the language barrier explaining the workings
is huge with their engineers )

-kert

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

·
Registered
Joined
·
70 Posts
Discussion Starter #20
From: Andrew Kane
> I conducted a bit of an experiment... small permanent-magnet fan...
> attached the fan to a pole... I got approximately 8 volts with
> peaks around 15. My WAG estimate of the wind speed is 25-40 mph...

A good experiment. Any PM motor becomes a generator just by turning it.

The *no-load* voltage is almost exactly proportional to rpm. If that motor ran at 1200 rpm at 12 vdc, then if you spin it at 1200 rpm it generates 12 vdc.

But, it's not doing any work. Watts = Volts x Amps. Power out is zero, because the current out is zero.

If you connect the motor to a load, now it will generate current. But two things are immediately apparent. First, the generator slows down a lot -- this is from the efficiency of the propeller (it is "slipping" in the air). Second, the generated voltage drops even more than can be accounted for by the reduced rpm -- this is because the motor is not 100% efficient (there is a voltage drop in the winding resistance, among other things).

You can see this most clearly by getting two identical PM DC motors. Couple their shafts with a piece of rubber hose. Run one motor from a 12v battery. At no load, the second motor will generate almost 12v (like 10-11v for typical automotive-grade motors). But put a load on the generator -- it slows down and the output voltage falls.

Try different loads. By measuring the input and output voltage and current, you will find that your best input-output efficiency is only about 30-40%. That's because automotive motors are only about 60% efficient, and 0.6 x 0.6 = 0.36 or 36%.

When the two motors are coupled with fans instead of a direct shaft coupler, the efficiency falls even more. With the badly designed propeller fans on most consumer products, you'll be doing good to get even 50% efficiency on each one, or 25% overall. Multiply that by the 36% of the two motors themselves. You'll find that the overall efficiency is just 0.6 x 0.6 x 0.5 x 0.5 = 0.09 or 9%.

9% efficiency might still be good enough, if the wind is "free energy". But if that wind was created by the traction motor moving the car through the air, then you have a bad deal overall.

Some years back, we talked about a contest to make some EV "hood ornaments" that used the various mad ideas people have to generate energy. Ones with a propeller, or solar cells, or generator on the wheel, etc. All they need to do is light a little LED, or just be an attention getter. Not much came of it, but it's an entertaining notion!

--
"Excellence does not require perfection." -- Henry James
--
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
 
1 - 20 of 22 Posts
Top