Newbie questions

[Lugnutz]

Hi everyone,

I'll start off admitting I know NOTHING!!  I've been doing some research on solar applications for a small project and that led me to wind power. 
This then led me down a road of many questions. I'll try to keep my questions as clear as possible.

1st.  Using a dc motor rated at 120 VDC at a RPM of 3400 and an AMP rating of 8.15, I figured that at 500 RPM I should be getting almost 18 VDC ( this is of course assuming I did the math correctly ) . 

2nd. If running the gen at 500 RPM, producing 18 VDC, do I still use 8.15 AMPs to figure my power output? I would think that the AMPs would need to be reduced by the same factor as the RPM and Volts ( I warned ya, I know NOTHING )

3rd. What kind of wind speed am I looking at to get the 500 rpm? I know blade size and design will play a big roll in this answer. Am I correct in guessing that 10 MPH winds probably will not do the trick?

4th.  If the gen began to produce 30 VDC what effect will that have on my charge controller?  Can this rise in current be kept in check?


Thanks for taking the time to read this over. I hope I was clear with my questions. I did try the search but I don't know enough to know what to ask!
Thanks
Rick

[Rover]

Your voltage at 500 is roughly correct. Are you planning to go into battery(s) .. . I'll assume you are.
1. The battery will hold down the voltage of the turbine, ok yes at 500 rpm it "can" produce 18V, but when connected to the battery it fall to the battery voltage, which if everything is working correctly, will slowly rise
2.  Charge controller, in the case of the turbine  and a battery connection, is the battery (Yes there are other ways, but not mainstream). You only need to worry about overcharging and losing load on the turbine which might cause it to spin wildly (a number of bad things go with that) , hence a "dump load controller"... look up Ghurd and controller on here .

[Lugnutz]

Yes this will be for a battery bank.  I doubt that I need a gen as big as I described for my needs, but it was handy since it gave me all the specs ( ebay ads just don't give you enough info to go on ). 

My project is a heating system.  I have an outdoor wood stove that uses a small blower that requires just over 100 watts.  I also would like to add a seperate blower to move more warm air from the kitchen ( where the stove delivers its heat ) to the bedroom ( where I get real cold ).  That blower if I recall correctly is also close to 100 watts ( both 110 vac ).

I was looking at a hybrid solar/wind combination.  I could probably accomplish my project with solar only, but wind power is pretty darn cool.

[TomW]

Yes this will be for a battery bank.

My project is a heating system.  I have an outdoor wood stove that uses a small blower that requires just over 100 watts.  I also would like to add a seperate blower to move more warm air from the kitchen ( where the stove delivers its heat ) to the bedroom ( where I get real cold ).  That blower if I recall correctly is also close to 100 watts ( both 110 vac ).

I was looking at a hybrid solar/wind combination.  I could probably accomplish my project with solar only, but wind power is pretty darn cool.

First advice I would offer is to drive a DC fan or DC muffin fans directly rather than use an AC fan. One less device to buy and fail (inverter). Lots of muffin fans can move air with less power than an induction motor from an inverter. .

Several folks have built very efficient air movers for DC (battery) power here.

If this is the only use for this starter system I would recommend DC all the way for simplicity and lower parts count in the system. You can likely shave power needs considerably doing this, also and reducing your need for more charging capacity as a side benefit.

Just where I would go.

Good Luck with it.

Tom

[Lugnutz]

Thanks for the replies Gents.

Tom, I already have the 2 motors ( the blower for the stove mounts to the stove) would I still save if I replace them with a dc unit?

I have found a blower for my stove that might work, I'd have to get the info off the current one for cfm and measure the output size.

Thanks again
Rick

[Bruce S]

Lugnutz;
  The thought would be to eliminate the losses from changing the battery voltage up to AC via an inverter.
Since you will already have a DC source, the better plan would be to size a fan/blower or multiples to push/pull the nice warm air to where you want it.

I'm pretty sure this is what Tom was stearing you towards.

 
Cheers
Bruce S

[Ungrounded Lightning Rod]

Hi everyone,

I'll start off admitting I know NOTHING!!

We all started there at some point.  Had to learn to walk and talk...

2nd. If running the gen at 500 RPM, producing 18 VDC, do I still use 8.15 AMPs to figure my power output? I would think that the AMPs would need to be reduced by the same factor as the RPM and Volts ( I warned ya, I know NOTHING )

Yep.  Current rating is about heating up the wires in the genny, burning out brushes, and the like.  Heating goes up with the square of the current so you don't want to exceed it (though you can get away with it for short transients and maybe exceed it SLIGHTLY due to added cooling in a wind genny application.)

4th.  If the gen began to produce 30 VDC what effect will that have on my charge controller?  Can this rise in current be kept in check?

As lugnuts pointed out, your voltage is regulated by tying the genny to the battery (through a blocking diode or a rectifier).  The battery holds the voltage down (because it takes a lot of charging to move its voltage or electrolyze enough of the electrolyte to put a layer of bubbles over ALL the plates and open the circuit B-) ).  You use a dump load to throw away extra power (by discharging it from the battery) to keep the battery from overcharging enough to take damage (or "boil off" enough electrolyte that keeping it full is an excessive maintenance problem).

With the battery holding the voltage down the current rises with the wind, putting more load on the turbine, which holds the RPM of the blades down somewhat - it doesn't rise in proportion to the wind in a battery-charging application.  The excess current is a burnout problem (unless the blades are very short and the genny 'way oversize for them), so you need an automatic system for furling the mill in high winds to prevent burnout.  (Most of us use a cute hinged tail trick to do that, causing the mill to turn away from high winds.)

[Isaiah]

One might look in salvage yards for dc radiator cooling fans.
 I have two here we are using this summer for cooling and ventilating chicken coops.
 The one is running off the excess off the solar panels. good luck