Ram Air Wind Alternator

[ketel0ne]

So here's the concept a, 6-8" Ram air tube from the grill to an 6-8" blade assembly with a larger pulley to a half sized pully on one of these alternators. I have several hundred pages of alternator documentation(zip file) of how to pull this off. Looking for your thoughts. Also thinking that a solar panel could be rigged into the setup as well against the battery.

http://cgi.ebay.com/Permanent-Magnet...QQcmdZViewItem

[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. Since the energy you gain from the generator spinning must result in some proportional increase in drag, I'm not sure it would help with auto efficiency at all. I think the best bet would be minimizing electrical consumption, disconnecting the alt, dropping in a couple deep cycle LA batts, and using the solar panel as much as possible.

[FormulaTwo]

before everyone here tells you not to do it.

just go freaking do it.
then tell us how it works out!

but seriously tho, only charging while moving etc....
the ram air will mess up your aerodynamics....


run it like this.... Put it in your back bumper, with a hole cutt for the fan, whatever u use to spin. make a scoop to it. THEN, have it so that it will capture the exhaust gas blowing onto it, as well as, the air you are generating while the car is moving.

[DracoFelis]

I would think your idea would just be trading direct alternator drag on the engine (the normal case), for aerodynamic drag on the car itself (since I would think the wind ram would cause additional aerodynamic drag, proportional to the power generated). This isn't exactly a win.

However, if you add an active shutter system (at the grill, in front of your "ram"), you could then use the system like this:

1) When the car is tuned off or stopped, the shutter opens, and therefore any wind blowing into the grill will generate some electrical power. If you live in a windy area, this would be a great way to top off a deep-cycle battery when you park somewhere.

2) And you might want the shutters to also open, when the break lights come on (i.e. when you step on the breaks, even very gently). This will allow you to usefully use the aerodynamic drag this "ram" produces to assist with breaking (and generate a little electrical power in the bargain).

3) If you don't have any other charging circuit (i.e. you have disconnected the main alternator of the car), and the battery is getting low, you might want an override switch to open the shutter and therefore have your ram start charging things (albeit at the cost of more aerodynamic drag, while charging).

4) At all other times, I would leave the shutter closed (this system turned off), to avoid the aerodynamic drag on the car.

NOTE: I don't see any reason you couldn't do both this and a solar panel. If you used deep cycle batteries, the combo might very well let you disconnect the normal alternator from your car, thereby lowering that electrical drag on the car. You would then be running mostly off of the deep cycle battery (or batteries), with the solar and wind power (and your idea is essentially a clever way to hide a wind turbine in your car) when you are parking. And you would even get a little "while you are driving" assist from the solar cell (if the sun was out), and the wind ram (if/when you are slowing down or stopped).

[JanGeo]

not enough air flow to make any power - small boat generators I have worked with have three 2 foot radius blades and only produce 10-15 amps in 20-25 mph winds . . . maybe at higher speeds with ducted air flow would work . . . extra battery means extra weight

[rh77]

Originally Posted by JanGeo

extra battery means extra weight

I'm thinking that if it's remotely possible, that it would be a supplement to the alternator. If it proves effective, a clutch mechanism similar to that of the magnetic A/C engagement, could cut the load from the alternator and use the wind. If this second step proves effective, a simple electronic system could be setup to engage/disengage the clutch, based on electrical load/wind generation.

No idea is too crazy here

Scientific testing can only determine effectiveness.

RH77

[Matt Timion]

It would work wonderfully at highway speeds IMHO, but what about city driving?

I still think that finding a way to do this with the exhaust gases would be the best bet. If you could rig it up to capture both exhaust and wind that would be the best.

[rh77]

Originally Posted by Matt Timion

I still think that finding a way to do this with the exhaust gases would be the best bet.

Agreed. A turbo could do a variety of things aside from just pumping more air into the engine. If you somehow hook it to a gearset to step-down the RPMs of the output, it could easily be an alternator or more. Due to the high speeds, precision crafting would be essential.

RH77

[JanGeo]

Anyway you do it, all you have to do is pump the current into the battery and the engine alternator will automatically not charge if the battery voltage is already high enough. The only thing you may want to do is let the battery run down a little if you know that wind power is coming down the road when you are heading for highway. An extra battery is also possible if you get a voltage booster you can pump the additional battery 12 volts up to 14 volts and feed it to the main vehicle battery you should be all set. I have a simple way of doing it with an inverter and a 35 amp switcher charger - might be interesting to give it a try then get something setup that will just boost the voltage directly like a beefed up hobby charger that operates off a 12 volt battery.

[DracoFelis]

Originally Posted by theclencher

I proposed such a thing to my engineer uncle when I was about 12. He said the extra aero load would negate the proposed engine drag reduction "benefits". There ain't no free lunch.

Which is why I was proposing that the OP use an active shutter system, so that the unit is only engaged (i.e. only have the shutter open) when:

A) You want regen braking. As you can easily get more aero drag, simply by opening the shutter. And all that aero drag/braking, generates "free" power for the car.

or B) You are already stopped. In which case the only power you will get out of the thing is on a windy day (when the wind blows into the unit). But such power (even when you are parked with the engine off) would occasionally come (more so in windy areas, less so if you park in a garage).

or C) Your battery is low enough, that you really need the extra power, and you are therefor willing to put up with the drag.


In case A&B (above) the power is "a free lunch" (beyond the extra weight of this contraption). And in case C, you will "pay the price", but you at least have an option to get the power if/when you really need it...