Author Topic: New Alternator Idea (Read 6028 times)

taylorp035 · « **on:** July 01, 2009, 04:59:19 PM »

I currently have a very nice general motors car alternator. It spins very freely, so start up should not be an issue. Now I know, most of you guys will be smashing your heads against the wall, but I think this might just work.

For every one's knowledge, this is going to be more of an experiment than a permanent machine.

There are two main problems with the alternator. First, there must be power to the field coils to start the generation process. I was thinking of making a super mini vawt that will generate just enough power to start the coils. I have done this before by using a small cheap dc motor. Once it starts, the alternator will kick in and power the field coils by itself. This leads to some interesting cut in wind speed theories/ideas that could get around some cogging / stalling start up issues.

Problem number two. The alternator probably needs to spin close to 800-1000 rpm to cut in. Obviously any kind gearing would be nasty and hard to work with. I was thinking of carving some really fast blades, maybe 5-8 ft in diameter,(probably closer to 5 for the speed). Does anyone here know what the cut in speed of a car alternator would be?

Also, i have 4 neo hard drive magnets that I could possible replace the field coils with. Any suggestions?

ghurd · « **Reply #1 on:** July 01, 2009, 12:05:14 PM »

Very unsuitable in the factory configuration.

Best to look at some earlier work.

Ed has some details,

http://www.windstuffnow.com/main/gm_alt_mod.htm

I like the type with the magnets between the rotor halves.

I can not recall who made a specific one, but it was nice. The magnets were from microwaves if I recall correctly. He moved to a place without internet.

Not that I recommend it, but wind-blue makes a rotor. The photos should show enough detail to understand it.

If in the common sizes, the 4 HD neos will not make much power.

Master Zubbly figured he could get 150W per cubic inch, and there is not many cubic inches in 4 HD neos. Be quite lucky to get 10W with a good design.

G-

taylorp035 · « **Reply #2 on:** July 01, 2009, 12:16:06 PM »

These magnets are somewhat beefy as they come from large 11 platter 1.5" tall scsi hard drives. There is probably 1/2 to a 1/3 cubic inch on each magnent. I was hoping not to tear apart the alternator.

taylorp035 · « **Reply #3 on:** July 01, 2009, 12:18:41 PM »

After looking at the web link, i think that is out of the question. 50 - 100 watts would be fine by me.

ghurd · « **Reply #4 on:** July 01, 2009, 12:46:00 PM »

Brain fart? A half cubic inch is 1" x 1" x 1/2".

If they are actually a half cubic inch, then I assume they are curved.

Might look into simple motor conversions. I think it is the only practical way to get Any power out of 4 normal sized HD neos. Curved or otherwise.

G-

tanner0441 · « **Reply #5 on:** July 01, 2009, 12:48:17 PM »

Hi

I have played with lots of alternators and I never found one that was suitable, 1000 RPM seems to be the lowest speed they start putting out. Remember car alternators run up to 12,000 RPM. Also what is your wind site like, because that easy to turn alternator, wont be so easy to turn when the rotor is pulling 5 amps through it, and 100W at into a 12V battery is round 10A a 12V battery will not charge with only 12V out of the alternator.

Make an adaptor and drive the shaft from a pillar drill and try at different speeds, then re-do the sums, I realised car alternators are a none starter.

Brian

taylorp035 · « **Reply #6 on:** July 01, 2009, 12:58:25 PM »

They are curved.

taylorp035 · « **Reply #7 on:** July 01, 2009, 01:06:07 PM »

Back towards my original idea...

The alternator provides almost zero resistance when the field coils have no power. I was thinking that I would have a mini windmill power the field coils once the wind got up to about 15mph or so. Also, I think i could get 1000rpm out of a 3-5ft blade set. I don't care if this set up only works 1 out of ten days. My wind comes down a corridor made by some big high tension power lines. The wind is only good when it comes from the north or south. I could have 35mph winds from the east and the windmill will not spin at all.

taylorp035 · « **Reply #8 on:** July 01, 2009, 01:07:12 PM »

50-100 max

ghurd · « **Reply #9 on:** July 01, 2009, 01:10:38 PM »

If they are half a cubic inch, "google search the board" (upper right menu) for "#29".

You might be really lucky!

G-

taylorp035 · « **Reply #10 on:** July 01, 2009, 01:44:57 PM »

If found this web that has my alternator and wiring directions.

http://www.webpal.org/webpal/b_recovery/3_alternate_energy/electricity/lawnmower/generator/thrpag.ht
ml

As you will see, I want to replace wire #1 with the mini windmill.

taylorp035 · « **Reply #11 on:** July 01, 2009, 01:56:50 PM »

I searched that. Mine have a backing that has two holes in them so I can bolt them down. That magnet itself is more like 1/4" thick, .75 wide and 2 inches long. Very powerful. They are all the same. I could probably get more, but they are a pain to get out of the hard drive (last time it took 3 hours for one).

ghurd · « **Reply #12 on:** July 01, 2009, 02:16:13 PM »

Found it.

WXYZSCIENCE's car alts,

http://www.fieldlines.com/story/2007/7/3/191357/4809

http://www.fieldlines.com/story/2007/7/4/225522/5838

Strange HD magnets you have there.

Make sure each has one pole on each side. Some have N/S on one end and S/N on the other.

Slide a small screw driver along it. If it jumps past the middle, it needs cut in 2.

Building a 'super mini VAWT' capable of suppling a workable field current will be a big job in itself.

The money, time, and effort required to do only that, will be much more than just building a basic 50-100W HAWT.

G-

taylorp035 · « **Reply #13 on:** July 01, 2009, 02:31:58 PM »

I was thinking that the mini vawt will only "start" the field, and then the alternator will power the field after some juice starts to be generated. The mini will only get some voltage in the coils to start the whole operation.

Flux · « **Reply #14 on:** July 01, 2009, 03:23:27 PM »

"I was thinking that the mini vawt will only "start" the field, and then the alternator will power the field after some juice starts to be generated. The mini will only get some voltage in the coils to start the whole operation. "

This is pointless, the field needs about 40 W to do much so your mini turbine needs to produce at least 40W. If it doesn't and you use it to kick the thing off you need your main turbine to produce 40W before anything goes into your battery.That power doesn't disappear it has to be produced from somewhere.

Let's take a bit of a realistic look at things. A fast 5ft prop could reach 1000 rpm in about 15mph wind. With a bit of luck it would probably produce 60W at 15mph so by the time you have supplied the field you would end up with possibly 20W rather than the 60 of a pm alternator. If you have lots of high wind and you only want very little power then you can get something from a car alternator. For most people on a normal lowish wind site it is a very miserable way to get very little.

In the old days we had little luck with car dynamos and their field requirements were less and the cut in speeds lower. Alternators are a step backwards.

If you replace the wound field with permanent magnets then you loose the 40W of wasted field power but you add iron loss and cogging to delay start up and you remove some of the flexibility of the wound field and ease of load matching. It is still a pretty miserable thing but at least it will do something from about 10 mph upwards.

To replace the wound field with permanent magnets is a fair bit of work and a few scrappy magnets aren't going far towards a decent solution so in the end the whole thing becomes a lot of work for something with mediocre results. If you want to go that way then fine, you will have fun and learn a lot and you will find out the hard way what everyone else has been saying about car alternators for years.

Flux

taylorp035 · « **Reply #15 on:** July 01, 2009, 05:17:51 PM »

Thank you Flux, that was exactly what I wanted to hear.

Therefore, I could have the cut in speed at about 14-17 mph, which would be fine by me.

bob g · « **Reply #16 on:** July 01, 2009, 09:16:11 PM »

if all you are after is in the higher wind speeds, i would go back

and drive the alternator with a stepup gear arrangement of some sort

and forget the secondary windgen to power the field all together.

bob g

dbcollen · « **Reply #17 on:** July 01, 2009, 09:56:42 PM »

Since it seems that all you want to here is what a great idea it is, here goes.

"What a great idea, amazing nobody thought of it sooner, it may even solve the worlds energy needs, if I were you I would patent it before anyone else steals your idea." There are no new ideas, just different ways of applying old ideas.

Now seriously, several very knowlegable folks here explained the pittfalls of car alternators and you are determined to go for it anyhow. by all means waste as much of your money as you want, it will not change the fact it won't work very well, if at all. Also you do not need an external exciting current for the field, the claw rotor will have residual magnetism and will cascade and supply your initial field current if spun up fast enough. Some of the factory internal voltage regulators will not allow self exciting, but if you did get it to work as a wind turbine you wouldn't be using the internal regulator anyhow.

Dustin

hiker · « **Reply #18 on:** July 01, 2009, 11:59:01 PM »

ive played around with car alts on my pedgens ...

only takes a 9v transitor radio batt to fire up the field coil..

if theres no load on the alt--just hit the field coil a secound with the batt--and it starts the ball rolling..from then on the alt will supply the power to the field..

some alts retain a small amount of magnatizem-some dont--thats when you use the batt..

your setup will work--like you said once the field coil is powered up-the alt takes over--and it only takes a few volts to get the field excited--then it builds up as the alt coils start output---have fun..............

bob g · « **Reply #19 on:** July 02, 2009, 02:32:25 AM »

also like to add

if you are even going to get a fighting chance of making watts with an

automotive alternator, start with a large frame unit, such as one off a truck

and forget anything built by delco

(this coming from a guy who loves delco products

because of limitations explained by all who have responded, you will have to forego

any decent return on power until you get upwards of 15-20mph

now it is possible using a large diameter blade set, of perhaps 12 ft

and using a serpentine belt driven large frame alternator, reconnect in wye rather

than the much more common delta, in 20mph plus windspeeds to get some reasonable power.

folks don't like belt drives because of two things, efficiency hits, and safety when the belt breaks

efficiency can be quite good if done right, even up to about 10:1 ratio, and

if you use a brake drum with the brake backing plate, w/shoes and parkbrake cable

there is no reason that a reasonably industrious guy could not figure a way of making an auto brake for run away protection.

your going to have to remove the oem regulator in favor of a balmar or xantrex controller, both of which are programmable for the amount of power available to drive the alternator. this is very important, without the ability to match the blades power to the alternator it is just a non starter.

personally i think it can be done, but not cheaply. it will take a serious commitment in time and money to make a workable system that makes a reasonable amount of power.

even then in windspeeds below about 15mph the unit is just going to sit there.

this alone makes this sort of scheme useless to all but less than 1 percent of sites in my opinion.

all said and done you may find your site is not up to the task of delivering

the required amount of windspeed for any reasonable amount of time per week.

bob g

bj · « **Reply #20 on:** July 02, 2009, 07:33:00 AM »

Taylor--I have messed with car alts for about 3 years now. I learned a lot, and it was fun, but am now building two Dan's 10 footers.

They can work, the truck cases are better, as a larger diameter will give

more voltage at a given RPM.

Tried various self energizing schemes, (although hadn't tried separate mini-gen)

It all comes down to the fact that you are giving up 5 amps to run the

field.

Had big doughnut neo's made, (N-35) 3 1/2 OD, 2 thick to replace the field

windings. Seemed to be the best.

You will still have to rewind the stator. My best was 19 turns of #16 per

coil. Really hard to fit in, but do-able. That gave me 31 volts, at what

I thought was 300 rpm, until I discovered my tach was on drugs. Fair to

say less than 500rpm.

There has been lots said about bearing problems, but I had none. Used

6203-2rs which is double sealed, not shielded. Put a few drops of a good

synthetic motor oil in the bearing. (just carefully pick out the seal)

Same bearing through 3 years, and nine different alts. Suprisingly, the

back roller bearing will need more grease once a year.

Ran with 5 foot blades, tried 3, 5, and 6. Mo furling, and very noisy in

high winds.

All in all, if you are serious, and your location warrants it for shipping, I will give you my spare rotor. It will save you that part, but

you will have to do your own rewinding, as that IS a real pain.

If you are interested, E-mail me, just put in something like Otherpower in the subject line so I don't throw it out with the trash.

Best of luck

BJ

taylorp035 · « **Reply #21 on:** July 02, 2009, 11:54:40 AM »

Wow... This got a lot of people all fired up. What I currently have is a bunch of time on my hands (summer vacation) and a spare alternator and a lot of woodworking tools to play with. I am not going to power anything major like my house or anything else for that fact. This project will probably only run for 10-20 hours and that's it. It will not be water proof and I don't have a tower because of zoning issues (4 issues -

#1 - 35ft township ordinance

#2 - near a major airport

#3 - there are major high tension power lines where I would put it

#4 - the rest of my property is completely wooded

also my wind resource is not very good 11.8mph average but up to 15mph average in the winter.

I also don't have any spare 12v batteries to play with.

Now back to my happy self...

I only build windmills that cost me $0, and so far I have built 4 that produce more than 1 watt. I once made one that had an 84:1 gearbox with 4ft dia. sheet metal blades that turned a 24v motor out of an old printer that produced 10 watts.

So in the end, I will probably not really make this, just an idea. Today I am working on a 3 phase brushless motor as a generator that came out of an old tape drive.

Thank you all for pointing out for me all of the potential pit falls of a car based alternator windmill. Sorry if I wasted your time.

An for who are interested, my house is all electric and has a geothermal system. We seriously considered buying a windmill, but then we looked at our consumption and it came out to 35,000 kwh a year! That's what you get for having 10 servers running and 2 electric furnaces with 240" of snow a year.

taylorp035 · « **Reply #22 on:** July 02, 2009, 12:17:54 PM »

I also just finished the mini windmill. It is a savonius (sp?) turbine made from 4" pipe and is 6" tall. It is hooked up to my 3 phase brushless motor that is basically a pancake motor. I tested it an got 5 volts at 2500 rpm with only 3 diodes, all phases in series. Also I got about 3 amps shorted out.

taylorp035 · « **Reply #23 on:** July 02, 2009, 12:20:24 PM »

I just did the calculations, and with a TSR of 1, 2500 rpm comes at 44.6 mph! Looks like I need to make a bridge rectifier.

Madscientist267 · « **Reply #24 on:** July 02, 2009, 12:24:02 PM »

You'll have fun with it, but thats about it.

Go diskless on the servers and you'll save a bit - I have a similar problem, and ditched the hungry drives for flash and its amazing the savings in power. Of course, flash is more expensive up front than spinning disk... I think the extra reliability made the difference for me. You'll be able to get more of them on a given UPS too..

Steve

taylorp035 · « **Reply #25 on:** July 02, 2009, 12:32:03 PM »

I actually have 5 laptops, and at least 6 servers plugged in. There must be at least 50 hard drives, most of them being old and 10-15k rpm. When a computer will not start without a 220v connection, you know you are in serious trouble.

We twice now have had a 1 month electric come in at over $700 and 7000 kwh.

taylorp035 · « **Reply #26 on:** July 02, 2009, 12:33:43 PM »

I did not mean to say that it was a new idea to the world. It was just an idea that I had yesterday that sounded fun.

Madscientist267 · « **Reply #27 on:** July 02, 2009, 12:58:54 PM »

LOL yeah, that's what made me look into alternate ways of doing things. I changed over to front/back end layout and flash for as much as possible for that very reason. Of course, my system is mostly static data; flash isn't the best idea if you're constantly writing...

I ditched the old poweredges and went with some x series IBM stuff... Lots of storage on the back ends, and a single front end running all the services. Its like the step between 'old school' and virtualization. Not sure of the exact numbers but the wife came back with something like "thats much better" - a good indicator that I went in the right direction. Of course, she's not exactly privy to what all went into changing over, probably a good thing.

(note to wife in case she's reading: I love you! <kiss>)

Steve

ghurd · « **Reply #28 on:** July 02, 2009, 01:18:31 PM »

Pretty lucky to get that much with 3 diodes and 3 phases wired in series.

Connect it Wye with 6 diodes.

Don't expect much power from that windmill.

It's effectively about 1/8 of a square foot, and will have a hard time turning itself.

G-

taylorp035 · « **Reply #29 on:** July 02, 2009, 02:50:15 PM »

I just finished attaching 3 bridge rectifiers to all 3 sets of coils. Each phase came to 3.3 volts and when wired together came to 9.92 volts at 2500 rpm. I didn't see what the shorted amperage would be at that speed because I think I would burn up the diodes. It must be at least 5 amps.

The motor has a round magnet with 8 poles and 18 coils, 3 phases, 6 coils per phase / all in series.

taylorp035 · « **Reply #30 on:** July 02, 2009, 02:51:28 PM »

Funny you say that, my dad who does all this stuff works for IBM

taylorp035 · « **Reply #31 on:** July 02, 2009, 04:29:16 PM »

here are some new performance numbers for the mini windmill

rpm = 9.89 volts
rpm = 4.71 volts
rpm = 0.95 volts

charging at 2500 rpm

cell = 3.79 watts
cells = 5.928 w
cells = 7.12 w
cells = 6.838 w
cells = 5.38 w
cells = 3.66 w
cells = 1.09 w

charging at 1500 rpm

cell = 1.18 w
cells = 1.25 w
cells = 0.31 w

ghurd · « **Reply #32 on:** July 02, 2009, 05:32:19 PM »

Try to learn some of the nomenclature.

There is really nothing in there I can understand within the context and parts description.

Guessing you somehow got about an amp out of a VCR type/style motor.

Usually Isc doesn't tell anything worth knowing.

The 2 to 3 cell numbers don't make sense to me, to the point of being completely irreconcilable.

Now, just for fun, see how much effective swept area will it take to get 7W of actual output.

Maybe at 5, 10, 20 and 50MPH.

Remember to figure in the coil resistance and losses, and PN junction losses.

I find it a lot more fun when it works.

G-

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Author Topic: New Alternator Idea (Read 6028 times)