Ram Air Wind Alternator

[DracoFelis]

Originally Posted by theclencher

Would it even turn over when the vehicle is stopped, only by wind speed? I think it would generate little, if any, under that condition.

I would suspect that would depend upon how strong the wind is hitting the grill. And that will depend upon how windy the area you live in is.

[ketel0ne]

With a wind gauge in a duct tube behind the grill 8 inches, I have the following data:

Top wind speed 78mph (top speed for commute was 75mph coasting down mountain)
Avg wind speed 37mph (avg speed for commute was 42mph)

I have no instaneous yet as I could not be under the hood and see the gauge. This was data from my daily commute this morning. Trying the lower grill on the way home.

[ketel0ne]

Further research, the max speed of the wind gauge I am using is 78mph. So the avg is affected as well. No complete data yet. Looking to borrow a higher power wind gauge. Possibly one with a remote data display. Oh how has the scangauge spoiled me.


ETA: The wind data is also not time specific over the commute. So no way to know how much time there was no wind to make the average.

[AlexK]

JanGeo mentioned there will not be enough power available, based on his experience with boat wind turbines. Actually it's a simple calculation to see how much power is available. A pretty good wind turbine would capture 1/3 of the available kinetic energy of the wind. At sea level, 78 mph, 8" diameter turbine, 33% efficiency, the available power would be 524W. That would be 37A (assume 14VDC) at perfect conversion to electrical power. Available power is proportional to wind speed cubed so slowing down really hurts performance. For example at 25 mph, current would drop to 1.2A.

I can't prove it, but it seems to me that covering the hole (to improve aerodynamics) and running the alternator from the engine instead would be more efficient. It's just a matter of conservation of energy. The power has to come from somewhere, and the inefficiency of the wind turbine would be wasted energy. Seems like the old grill block is a pretty good idea.

[GasSavers_Ryland]

what is the average electrical draw on a car? around 80-90 watts for engine electrical, 20-50 watts for radio, 200 watts for all the lights that come on with the head lights, am I missing anything?
now the Air 403 wind generator's specs are as fallow:
Rotor Diameter: 46" (1.14 meters)
Weight: 13 lbs (6 kg)
Start up wind speed: 7 mph (3 m/s)
Voltage: 12, 24 and 48 volts (Inquire for others.)
Output: 400 watts at 28 mph (12.5 m/s)

average vehicle speed is what, around 25mph? so unless you do alot of highway driving you might end up needing a prop close to that size if you are going to do any driving at night, or in the rain (head lights on), now of corse if you were running a race car without any other electrical loads, you could get by with a much smaller prop and generator.

[cfg83]

Hello -

There is a website with a Honda Insight that uses a "drop down" 5th wheel for starting the car. This is the closest I could find (search for Mike Dabrowski) :

http://www.greencarcongress.com/2006...our_de_so.html

How about a drop down wheel for regen breaking? I did some calcs on the item in question :

Assume : 10" diameter 5th wheel = 5" Radius
Circumfernce = 2*PI*R => 31.4" => 2.61 feet
Max RPMs for this alternator = 18,000

18,000 * 2.61 feet => 46,980 feet per minute maximum for alternator

60 MPH => 1 Mile Per Minute => 5,280 feet per minute

5280 / 46,980 = .11 => 11% => At 60 MPH, when the altenator connects to the road, it will only be at 11% of it's maximum design load.

With a clever design, you should be able to create a regenerative break system. When you hit the break, the wheel goes down. If you keep it inline with one of the wheels, you should be able to reduce the drag penalty.

I don't know how to achieve the "clever", part, however .

CarloSW2

[JanGeo]

Don't think in terms of max rpm for max output - it can output a lot of power at lower rpms also. You should belt couple it to the wheel anyway and gear it up - be good to spin up the tire however or there will be a lot squeeling tires.

[red91sit]

Originally Posted by cfg83

Hello -

There is a website with a Honda Insight that uses a "drop down" 5th wheel for starting the car. This is the closest I could find (search for Mike Dabrowski) :

http://www.greencarcongress.com/2006...our_de_so.html

How about a drop down wheel for regen breaking? I did some calcs on the item in question :

Assume : 10" diameter 5th wheel = 5" Radius
Circumfernce = 2*PI*R => 31.4" => 2.61 feet
Max RPMs for this alternator = 18,000

18,000 * 2.61 feet => 46,980 feet per minute maximum for alternator

60 MPH => 1 Mile Per Minute => 5,280 feet per minute

5280 / 46,980 = .11 => 11% => At 60 MPH, when the altenator connects to the road, it will only be at 11% of it's maximum design load.

With a clever design, you should be able to create a regenerative break system. When you hit the break, the wheel goes down. If you keep it inline with one of the wheels, you should be able to reduce the drag penalty.

I don't know how to achieve the "clever", part, however .

CarloSW2

Hmm very intersting, i was considering a very similar system, however mine will use a small motorcycle rear end, (powered 5th wheel) for highway cruising.

[cfg83]

red91sit -

Originally Posted by red91sit

Hmm very intersting, i was considering a very similar system, however mine will use a small motorcycle rear end, (powered 5th wheel) for highway cruising.

Ok, I found the Insight 5th wheel guy on another GasSavers posting, so you can have his tech solution for reference :

http://www.99mpg.com/mikesinsight/

CarloSW2

[MetroMPG]

Somehow I missed this thread...

Originally Posted by omgwtfbyobbq

The only problem I can think of is efficiency. According to wikipedia (maybe?) the best (small) permanent magnet generators are ~60% efficient while most new alternators are ~55% efficient (bosch PR), and circa 2004, ~70% efficiency for the best bosch versions.

Can you point to a source for that info? Wikipedia (all of which is true, btw) claims 90% alternator efficiency:
http://en.wikipedia.org/wiki/Alterna...harging_system