Re: Mechanical Question about project Urgent!
 

If you are looking to recover energy lost by a car, you would be better off trying to recover heat from the engine and brakes.

Re: Mechanical Question about project Urgent!
 

Thanks a lot guys; this is really informative.

I understand your arguments, and I too believe that I will not recoup enough. But I think it is a useful experiment. At the ver yleast I can learn more on this subject.

So I just basically stacked the PAPST large CPU fans on the hood of the car, perpendicular to the ground. I have 3 of these large fans. They are wired in series and connected to a resistor. I will use hte multimeter to read voltages when driving hte car at a variety of speeds. After this I will calculate the power and then I can see how much I generate. Unfortuantely I will not be able to see the increase of my drag coefficient with this assembly.

Any thoughts?

Once again; I cant thank you guys enough for your input.

Re: Mechanical Question about project Urgent!
 

Brenn,
What is the part number of your fans. Most of the Pabst line is brushless.

Re: Mechanical Question about project Urgent!
 

I was able to use my fan as a generator.

I used a 1 k-ohm resistor and read the voltage across the two leads.

My data as follows:

15 mph = 1.20 V
20 mph = 2.06 V
25 mph = 2.68 V
30 mph = 2.83 V
35 mph = 2.77 V
40 mph = 2.82 V
45 mph = 2.70 V
50 mph = 2.52 V
55 mph = 2.26 V
65 mph = 2.21 V

The fan probably was not designed to handle such high rpm's past 40 mph.

Can I make any conclusions from this data taht will allow me to test the efficacy of using fans. Please note that I was not able to calculate how much the overall drag coefficient increased on my car.

Thanks so much for all your help.

Re: Mechanical Question about project Urgent!
 

You are making about one hundredth of one watt of power...that's not much!

P = E^2 / R

Re: Mechanical Question about project Urgent!
 

hmm...is htere any practical usage for one hundredth of one watt of power? Remember that I have 5 of these fans. So its more like one twentieth of one watt of power.

Re: Mechanical Question about project Urgent!
 

Hey Bren, try wiring the fans in parallel and see what happens.