Author Topic: alternator/electrical questions (Read 3779 times)

boarder girl · « **on:** May 13, 2005, 03:00:35 PM »

I have my first prototype turbine and nozzle almost complete. I hope to set it up and get the runner turning this weekend (I'll send pics when I get a chance). It will be operating off of the flow from the corregated discharge tube at this point. I do have plans to make it more efficient by running 4" pipe system inside the downspout/discharge system, as a penstock - but saving that for later. Want to see what kind of power I can generate from the current configuration.

I think I have a handle on the mechanical portion of this project but I am clueless on the electrical part. I have an alternator off of a Cushman utility vehicle. It has a built in regulator (I'm told this will prevent overcharging the batteries).

questions:

Do I have to turn this alternator at a certain rpm to get it to work?
How can I measure the rpm at the runner? This will help me design the right pulley system.

My thought is to charge batteries (12V) and run a DC air compressor intermitently to aerate the pond. I would want the system to sense when the batteries are running low and shut off the compressor, giving time for the batteries to recharge and then turn on again.

Does this sound feasible?
What kind of controller do I need to do this?

If anyone could share a schematic of what this system might look like that would be helpful.

Thanks!

P.S. sorry if I repeated this. The first time I posted, I don't think I picked the "hydro" section.

ghurd · « **Reply #1 on:** May 13, 2005, 09:44:48 AM »

Alternators like that have problems, like they use a good part of the power to make the magnetic field (where we use magnets).

Maybe the right stepper motor could get some power for testing.

They should turn easy for use with not much head. Cheap too.

The rpm will drop under load.

(Tiny, but I'm waiting on a batch of these with high hopes,

http://www.goldmine-elec-products.com/prodinfo.asp?number=G14781&variation=&aitem=3&mite
m=5

http://www.goldmine-elec-products.com/prodinfo.asp?number=G9550&variation=&aitem=5&mitem
5 )

Search 'low voltage disconnect circuit'. Some are easier than others. "http://www.maxim-ic.com/appnotes.cfm/appnote_number/2237">http://www.maxim-ic.com/appnotes.cfm/appnote_number/2237

Maybe a 'dump load' with a wider operating range. All about the same idea.

Some kind of off the shelf solar controller with LVD might work. Watch out for the open circuit voltage rating. Some are kind of low, so if the battery gets disconnected it could cook the controller.

Like a SS-6 with LVD would be OK, if the open circuit voltage of the alternator was always below 25v or so. Maybe a very simple shunt regulator between the alternator and controller, set at 20v.

G-

ghurd · « **Reply #2 on:** May 13, 2005, 09:45:31 AM »

Got me on what happened there

Ungrounded Lightning Rod · « **Reply #3 on:** May 13, 2005, 02:08:35 PM »

My thought is to charge batteries (12V) and run a DC air compressor intermitently to aerate the pond.

Why not have it run an air pump directly?

For that matter, if the water is going into the pond, you could run it through an aspirator and then discharge it at the bottom, and end up with no moving parts but the water. B-)

Vernon · « **Reply #4 on:** May 13, 2005, 02:18:31 PM »

The alternator will work over the range of RPM's that it turned when mounted on the original vehicle. I would estimate that 2000 to 6000 RPM would produce a regulated 14.2V output if the alternator is good. It will take perhaps 3K RPM to get full rated current if that is needed and I would try for 3K RPM because the field will draw less current and the installation will be more efficient at that approximate speed. If this is a very low power installation, less than around 200 Watts, a PMG will be a better choice as the field loss (about 30W) is eliminated.

A voltage comparator set to operate and drop out a relay at 10.5 Volts will save the a lead acid 12V battery from damaging excessive discharge. Strobe tachs are available that will accurately measure the RPM of the wheel .. or alternator for that matter.

Experimental · « **Reply #5 on:** May 14, 2005, 06:33:36 PM »

Hi Border Gal, have watched your posts with great interest and really envy you, for haveing that pond !! ( any fish in it

)

I really don,t know how much I can help you, as i don,t have much experence with water systems, But a lot with alternators -- enough at any rate to say, standard alternators are really a waste of time -- unless you can spin them fast enough -- then there are other problems to contend with, and I won,t bother going into that !!

Only one alternator type, I have had good luck with, is a small one used on a lot of Kabota powered equipment, and the modified PMA,s offered by several manufacturers...

The ones, used by Kabota (think I,m spelling that right!!??) are small, with a permanant magnet hub and they work, fairly well -- BUT I really think you might be better off, building one of the units like the ones on this forum !!

The big problem I see, is the head pressure you need to turn most alternators, at the RPM, they need to operate -- but one of the type offered by the creators of this board, could probably operate well, with a slightly modified water wheel..

You would be turning in the 200, 300 RPM range and all the control devices and such are available -- and with your background, you could build your own -- the plans are available, on line --FREE !! (scoraig wind site)

I,m dumber than a rock, and I still built three of there load dumps, from the plans i got off there web site -- one of these, could be used on the things you want to power, and they are adjustable, so you could keep your batteries nearly at full charge !!

Hope I have been somewhat helpful, and still want to know if there are fish in that pond --I have my fishing gear handy --Always !! Bill H.....

ghurd · « **Reply #6 on:** May 14, 2005, 07:29:58 PM »

Stupid try at a fix...

Search 'low voltage disconnect circuit'.

Some are easier than others.

"http://www.maxim-ic.com/appnotes.cfm/appnote_number/2237">http://www.maxim-ic.com/appnotes.cfm/ap
pnote_number/2237">http://www.maxim-ic.com/appnotes.cfm/appnote_number/2237

Maybe a 'dump load' with a wider operating range.

All about the same idea.

Some kind of off the shelf solar controller with LVD might work.

Watch out for the open circuit voltage rating. Some are kind of low, so if the battery gets disconnected it could cook the controller.

Like a SS-6 with LVD would be OK, if the open circuit voltage of the alternator was always below 25v or so. Maybe a very simple shunt regulator between the alternator and controller, set at 20v.

G-

boarder girl · « **Reply #7 on:** May 15, 2005, 05:54:14 PM »

Ok, don't laugh! Hope the pictures come thru. It's crude but it does turn. I will guess 60 rpm. I could count the set screw on the pulley going around - it sounded like one per second. Thanks for all your comments. I didn't have a good feeling about the alternator. I don't think they make pulleys big enough for me to get 3000 rpm out of it. I think there's a good chance I can get my hands on rotors and stators. Maybe I can use the mill at work (after hours) to machine seats for magnets. I have to admit, most of what you guys said about alternators is greek to me. I will get someone knowledgable to read these threads and translate for me.

This is not the design I plan to proceed with. I just was anxious to turn the wheel! I have plans to run irrigation pipe (penstock) thru the corregated tube...all safety for excess flow taken into account. Now if I can just get husband to "buy into it". : )

My next goal is to take the fan apart, paint it, replace the bearings (there from 1947) and design some waterproofing into it. It will probably be a while before I am making power : ( unfortunately.

Thanks for the moral support.

Great fishing by the way. That's why I want to aerate. Its getting very algae/weedy...could become a stinking mess.

Regard,

Lori

ghurd · « **Reply #8 on:** May 16, 2005, 08:11:19 AM »

Nice!

The foam out the back makes it look faster than 60rpm.

There was some talk about what type of bearings to use.

The tight seals on some hold the power back, unless they are trimmed (?).

I wonder how it would turn one of those $10 tread mill motors?

http://www.fieldlines.com/story/2005/3/23/225230/317

G-

ghurd · « **Reply #9 on:** May 16, 2005, 09:23:00 AM »

Sorry. Should have said where to get the motor!

http://www.surpluscenter.com/item.asp?UID=2005051610104230&item=10-2167&catname=electric

Shipping is more than the motor!

Here is what it did for me, old post copy/paste:

The treadmill motor.

Better than I expected! 5 ohms, 15v open by hand (no ropes), 2A short (hard to get a full turn by hand). It will take some figuring for me to get something to spin it for better tests.

There is a big ol' honkin' flywheel. Cast iron, balanced, 6" dia, 1/2" thick, with 11 fins (fan) measuring 1.625" long, 5/16" thick, 5/8 tall. A few holes and it's ready for blades.

There is some slop in the bearings. The shaft moves in and out about 1mm, and the bearing center moves with it.

All in all, not bad for $10.

G-

PS- Norm has it now, but I think the bearings are more suited

for hydro than wind.

Somebody had a test with wind blades on it, but I can't find it!

Experimental · « **Reply #10 on:** May 16, 2005, 10:32:38 AM »

Hello Lori,

Well, I,ve been holding off saying anything, because I didn,t want to be the guy to throw a monkey wrench into your plans --- But, knowing how that fan assy you are useing is constructed -- I seriously doubt it will work for you !!

A really quick test, would be to put a stick or 2 X 4 against that pulley and I bet you could stop it from turning, pretty easily --and you are going to need torque to spin any kind of generator !!

BUT, don,t be discouraged -- it could be modified to work better by adding some flat plates from some of the outer blades, to the inner shaft -- forming a simple paddle wheel !!

That won,t be the best design for this use, but will add power to it thru shear weight of the water !! BUT, one drawback I see is, being emersed in the stream, will cause the "back" of the blades, to push water -- this will rob some of your power ....Lifting it up, out of the stream, will help a lot !!

I wish I were a little more knowledgeable about computers -- I would draw you a picture and send it to you -- BUT, I,m old and dumb and it,s surprising that I can even manage email!!

Don,t know where you are located, but if you and your husband are anywhere near Washington state, I would be glad to come and take a look ( with my fishing pole, of course !!) and a drawing of something that "might" work !!

Ghurds idea for a gen, might do that part, but your turbine needs more work first and some of the other guys may come up with a better idea -- I remember seeing some turbines on this forum, just for water, you might try looking back thru the archives -- But , most were pretty complex !!

ONE question -- do you always have this flow of water, or will it deminish in summer

Above all, don,t be discouraged -- keep working --My best to you, Bill H....

ghurd · « **Reply #11 on:** May 16, 2005, 10:51:20 AM »

I wondered about lifting the blades (whole thing) up a little too.

Just shorten the yellow rope about 2"?

There is a lot of flow there, kind of thought it may just be blasting out the back,

not causing much drag.

That treadmill motor turns very easy. Very little bearing losses.

I could keep it past 10V with my finger in the 'fins'. Yup, Painful.

Seems like a good first try for the low speed setup.

Need to try a few pulley sizes I'm sure.

Maybe even plywood pulleys, just to find the right size?

Mr. Lori may like the idea of a $10 item that works,

instead of $100 in just magnets.

She can spring the upgrades on him later!

G-

boarder girl · « **Reply #12 on:** May 16, 2005, 11:08:09 AM »

Ok I don't quite understand. How do you get a treadmill motor to produce electricity? Do you have to modify it in some way? What kind of motor is it? I visited the link. I hear mention of PM motor. What is that. I can get motors. Let me know what kind to get. I will ask around here at work. They throw them away all the time around here. Sorry for being such an electrical dummy! : )

ghurd · « **Reply #13 on:** May 16, 2005, 11:53:12 AM »

How do you get a treadmill motor to produce electricity?

You spin it!

Do you have to modify it in some way?

Nope!

Need a diode (1 way check valve) to keep the battery from making it run as a motor.

Then the electric the motor makes goes into the battery.

PM motor. What is that.

Permanent Magnet.

Ask about PM, DC, high power, low RPM motors.

Wish you luck, but I doubt if they use any.

You don't want a gear head motor. At least I don't. Too hard to turn.

High power means low coil resistance, so you don't waste so much

just trying to get it out of the motor.

Low RPM means it won't need to spin so fast to get it up to the volts you want.

Most common DC motors tend to go 'fast',

way too fast to be easy to use for this kind of thing.

A rule of thumb that never really works for me...

Say you have a 140V DC PM motor rated at 1000 RPMs.

And you want 14V. So it should make 14V (1/10 of the rating)

At 100 RPMs (1/10 of the rating).

A quick test to see if it is a cantidate.

Spin it. Remember how hard it turns.

Connect the motor wires to each other.

Spin it. If it is a 'lot' harder to spin, it is worth looking closer.

G-

boarder girl · « **Reply #14 on:** May 16, 2005, 02:09:16 PM »

Thanks, I'll get on it.

ghurd · « **Reply #15 on:** May 16, 2005, 10:57:40 PM »

If you get one of those $10 treadmill motors,

post it RIGHT HERE, and I'll tell you

how what where when

to connect the diode.

I'd offer to come help, with my fishing pole too,

but those leaves look foreign to me.

boarder girl · « **Reply #16 on:** May 17, 2005, 05:30:38 AM »

Great info. Just for the record I'm hoping to run a 4" pipe system thru the corregated system (I've figured out how to do it). So my runner will be fed by a penstock instead. This should be much more effecient. Calculations suggest 100-150 watts. Also, Nando informed me that my wheel is too big. I need to find 6" dia. which I am trying to do right now.

boarder girl · « **Reply #17 on:** May 31, 2005, 06:59:49 PM »

Ok I got the treadmill motor in. Tell me about this diode. I'm anxious to try it out on the current prototype. I hope to be building prototype #2 which will consist of a smaller wheel for more RPM (still looking for parts). Thanks for the info. This is fun!

Lori

ghurd · « **Reply #18 on:** June 01, 2005, 05:36:41 AM »

Hey!

I was starting to wonder if you gave up!

Will test the motor today, post it this evening.

G-

ghurd · « **Reply #19 on:** June 08, 2005, 02:22:21 PM »

Lori,

Duh. I must have hit the wrong button.

Maybe this is too late.

With the motor over the fan, and the pulley over the pulley.

The motor turning clockwise looking from the pulley end.

The Red is positive.

So the diode goes between the red motor wire and the positive battery terminal.

Most diodes have a black stripe at one end. The stripe goes toward the battery.

Radio Shack has 6 amp diodes that should be good enough for testing the setup.

The higher the voltage the better.

They only list 6A 50V, #276-1661.

I would prefere something heavier for permanent. Maybe a 25 amp 200V "Bridge Rectifier". It is actually 4 diodes in a heavy case with 4 terminals.

Easy to connect and mount, and has a heat sink built in.

The red motor wire connects to either (or both would be better by using 2 of the 4 diodes) of the " ~ " terminals.

The " + " terminal goes to the battery.

Radio Shack lists a 25A 50V, #276-1185.

Sorry,

G-

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Author Topic: alternator/electrical questions (Read 3779 times)