10 footer questions

[gsw999]

I have built a 10 footer and have a few questions ( please bear with me im new to this )

firstly , its a 24volt model with 140 turns 16awg wire , 24 magnets 2x1x.5" , it has metal blades on at the moment which are about 3feet long , I know this isnt ideal and Iam in the process of trying to build some wooden blades which i will get done soon.

The turbine seems to work well and furls a little bit once left to run free, havent had any real winds here yet but tomorrow expecting 25mph wids so looking forward to that.

I have the three phases set up to a single rectifier which outputs to 2 dc wires.

i dont have a charge controller connected at the moment as i am running from some old lorry batteries that have seen better days, anyway when i connect up 2 batteries it runs at 26 -29volts , 4 batteries 48-55 volts, when the turbine is allowed to run free ( not ideal i know ) the turbine puts out anywhere from 60 to 100 volts, my main question is, if it was connected to a grid tie inverter would I be "taking advantage " of the increase of power that the turbine as its not "held back" by the voltage of the batteries.

also when the turbine is connected to 24 volts is it the job of big blades to crank it round harder so its charging with more amps  , on the subject of amps I tried checking the amps with my 10$ multimeter set to "10A" but didnt get a reading.

I guess I just need to do more research to understand better whats going on.

Thanks

Gav

[Flux]

I think you might have a steep learning curve to come. Some of your questions are a bit vague, such as the bit about the rectifier. Unless you have a 3 phase bridge I suspect you have it connected single phase.

The 3 ft metal blades are a total unknown in the equation but certainly it will behave very differently with the proper 10ft wooden prop.. I also think 140 turns is high for a 24v machine unless you have copied the very old design that was connected delta.

The power you get in low winds with only a 6ft slow prop will be fairly limited with the poor matching to the alternator so that and the possibility of it being connected for single phase will mean you get only a small current and depending on your ammeter you may not be able to measure it. With small prop and lots of turns it will need to work at a fairly high voltage and that means lower current anyway.

A grid tie inverter would in theory get you more power than battery charging by matching things better but you are a long way from going down that road yet. I am not entirely sure you have seen any power out at all yet so wait for more wind and see if you can measure any amps into a battery. No way will it be furling, you are probably seeing the effects of turbulent wind.

Make sure you have it connected properly with a 3 phase rectifier and you can try it in better wind with the present prop but don't expect much. You need to build the 10ft prop before you can start to do much serious testing.

Flux

[gsw999]

It is connected to a three phase retifier , and yes I have a very steep learning curve ahead of me like mount everest , its just that when its tied to 24volts I am guessing it needs the bigger blades on it to stand half a chance, I will get on the blades this week.

[galeforce jones]

also when the turbine is connected to 24 volts is it the job of big blades to crank it round harder so its charging with more amps  , on the subject of amps I tried checking the amps with my 10$ multimeter set to "10A" but didnt get a reading.

Not sure if you're familiar with multimetres? You can only check amps in series with the load (the battery in your case)

[Flux]

If you are using a 3 phase bridge that is fine.

I think with 140 turns you will need to connect in delta to work properly at 24v even with the correct prop. You can try it in star but it will stall before you reach cut in and never get away properly. It should work fine for test purposes at 48v in star and if it does then you can reconnect for delta when you get your final batteries.

Flux

[gsw999]

also when the turbine is connected to 24 volts is it the job of big blades to crank it round harder so its charging with more amps  , on the subject of amps I tried checking the amps with my 10$ multimeter set to "10A" but didnt get a reading.

Not sure if you're familiar with multimetres? You can only check amps in series with the load (the battery in your case)

Right thats my problem then , I am checking "trying to check" amps on the dc wires coming from the turbine.

[gsw999]

If you are using a 3 phase bridge that is fine.

I think with 140 turns you will need to connect in delta to work properly at 24v even with the correct prop. You can try it in star but it will stall before you reach cut in and never get away properly. It should work fine for test purposes at 48v in star and if it does then you can reconnect for delta when you get your final batteries.

Flux

Ill be honest I have heard of this but dont know really what the difference is , can you "alter" it after the stator has been made?. so ,much to learn . i always try to run before I can walk!!!

[Flux]

You can only alter it if you have brought out the 6 leads. If the star point is connected inside then you can't.

On the subject of measuring current with a multimeter, unless you are sure what you are doing it can be tricky. You need to connect the meter in the lead from the rectifier to the battery and also most meters have another connection for current. One is common to the volts and the other is usually marked 10A. if by any chance you manage to connect this connection as for a voltmeter you will blow the internal fuse with the current that a battery will supply.

[galeforce jones]

On the dc side of the 3 phase rectifier you have a + and - connection. The meter will be placed between the + on the rectifier and the + on the battery, you really should have a fuse close to the battery on the + side. It would be better to use a dc panel meter at least 0-50 amps for a 10 footer.

[zvizdic]

 its a 24volt model with 140 turns 16awg wire , 24 magnets 2x1x.5"

140 turns is a 48V not 24V

http://www.otherpower.com/stator.shtml

[ChrisOlson]

firstly , its a 24volt model with 140 turns 16awg wire , 24 magnets 2x1x.5" , it has metal blades on at the moment which are about 3feet long

Gav, this thing should cut in at about 70 rpm, which is way too low for 10 foot blades, and even worse for a 6 foot rotor.  Are you sure you have the specs right?  This machine won't even work on 24 volt, or at best maybe deliver up to 10 amps with a 10 foot rotor.

Your rotor has to spin to make any power, and you got this one wound to run way too slow.
--
Chris

[gsw999]

Thanks for the responses, Im still learning this stuff, thought if I built something everything would all fall in to place , my problem is I dont understand the basics about resistance, batteries , testing stuff , circuits etc all the stuff you needs to know to make stuff that works, but this is a learning curve.

It does turn really well at the moment , and its been out in some wind and is still standing, can anyone suggest a more appropriate winding for the stator, looking to run a 24v system just to power basic stuff via a 24 volt inverter , security lights etc.,I can buy whatever wire is needed , I dont know about different types of windings, star / delta etc , this is just another thing I am looking to learn.

as for the blades I need to have a go at making some , was speaking to a carpenter I met the other day he is up for making some blades but will wait on the stator first and take it from there.

[birdhouse]

being a carpenter...

i dreaded carving blades.  they only have one straight edge, and are complex curves.

i opted for the chainsaw method derived from a member here oztules.

a 24 grit flap wheel on an angle grinder finishes them up fast. 

here's a vid of me chainsaw carving. 

http://www.youtube.com/watch?v=vXfN3lM-xOU

worth looking into! 

adam

[Flux]

For star connection with those magnets then 140 turns will give you a 48v winding. If you had not made the star connection inside then you could have connected it delta. This was a very early option for the 10ft machine and I suspect that is where you got your data from.

If you follow the modern plans then all the connections are for starand you will need something like 70 turns. I suggest you look at the information for the current project and use the latest figures for turns and wire size. For a newcomer you would do well to buy the book and benefit from a lot of additional data.

If you are good at brain surgery and can remember where the internal star point is made you could probably get inside with a dremel tool or similar and break the star point and bring the extra 3 leads out and change to delta. If you can manage this your winding will work fine on 24v.

Flux

[gsw999]

I am sure its wired in star with coil 1 to 4 to 7 , 2 to5 to8,3 to 6 to 9.

Maybe I have made a 48volt one which doesnt appear to be a problem when wind is over 10mph, I haved connected the system to 4 x 12v batteries and will await some wind.

I had it running directly to 3 12v batteries ( no controller ) and I had a 12v inverter connected to one of the batteries with a 400 watt security light and it was running it for over an hour with no loss of charge ( bank kept slipping down then popped back up with a bit of wind so its def making/putting power in, its probably non standard to put a 12v inverter into a system that is using different voltage but my 12v 1000watt inverter seems to be more stable than my 800w 24v ( both cheapies ), keeping the tests going.

How do i test the amps going in to the batteries, is there a good bit of kit i can use or will a correctly connected multimeter suffice?

Thanks

[Flux]

You can use a multimeter on the amps range as long as you don't exceed the rating and blow the fuse ( I always do and gave up years ago).

Otherwise you need an ammeter big enough to deal with your expected current, used to be common on older cars but not so easy to find now. You may get something on ebay if you watch what you are buying.

The best way is to use a shunt in series with the battery feed lead and use a millivoltmeter to measure the volt drop. You can use your multimeter on the lowest dc volts range. You can use an expensive commercial shunt or you can calibrate a bit of wire and measure the volt drop across that. There is a fairly well known length of a certain AWG wire that has been mentioned here many times, you can probably find it. I don't remember it as we don't have AWG wire here.

You can work these things out from wire tables but you are probably not at that point yet.

Flux

[TomW]

A 1 foot piece of #10 solid copper wire will drop 1 Millivolt per amp of current flowing through it.

I think they are good up to 150 amps as mine see that occasionally in use.

50 amps is probably a better max rating.

Very good for "close enough" cheap home brewed shunts.

I use a couple of them here with cheap EbaY analog meter amp gages.

Tom

[Flux]

Thanks Tom, I knew someone would come up with the answer.

Just need to explain that it goes in the lead from the rectifier to battery positive. The multimeter set on mv range will then read charging amps, I hope it is easier to understand than trying to explain how to measure amps with a multimeter.

Flux

[gsw999]

Thanks guys I had a problem with my multimeter readings due to a low battery , it seems to be putting out 24 volts at about 70-80 rpm after that it gets pretty hard to tell.

i missed out on a couple of 1kw grid tie sma inverters on ebay 250$ each reckon it would have been worth a go even just for the future.

[bob golding]

as for the blades I need to have a go at making some , was speaking to a carpenter I met the other day he is up for making some blades but will wait on the stator first and take it from there.

its not as hard as it sounds to make a set of 10 ft blades. i have done it with nothing more than a pencil, a sharp,new, saw and a spokeshave. a workmate or a decent bench with a vice is all you need. mark out your profile on a piece of 6x2 from jewsons or travis perkins.  this will be a bit thinner than recommended but will work. i use windstuffnows profile. its on his website.

the hardest part is cutting down the grain. takes forever to do, which is why you need a new saw. irwin panel saw about 7 quid from b and q is what i use. after you have cut down the grain on the flat side putting the twist in is really easy if you follow hughs instructions. something to  check the thickness helps but it is a pretty forgiving design so as long as they weigh about the same they will work.

the last set i made are still flying after 3 years. gave them a bit of tlc by filling the  leading edges with polyeser filler and leading edge tape a couple of months ago. otherwise they have worked fine even up to a 85 mph gale. the turbine got trashed but the blades survived.

[Flux]

Strangely I have not in general found carpenters to be the best people to make blades, a good carpenter will be able to make anything from wood, but the concept is quite different from what they normally do and you will have a job explaining the marking out process.

If you can't get your head round the marking out process then just don't attempt it or at least just practice on a bit of scrap wood until you get to visualise the shape.

Once you are confident with the marking out then the rest is easy, I prefer to do it like Bob with hand tools but you can use any method that removes wood. For big blades the chain saw method is excellent but you can do it with a power plane and an angle grinder with a coarse sanding disc if you can live with the stink and noise.

Once you have made a successfully blade you will find the next 2 easier and it really is not as intimidating as many imagine. I made a pvc prop once, it took me longer and the end result was not something I would consider a thing of much use, I really don't see why people go this way when a decent wooden prop is pretty much within the capability of any reasonably practical person.

Flux

[gsw999]

Cheers guys, just moved in to a new unit where I have plenty of space to set up Jigs etc, I have 2 of Hughs books, the older one seems to have better instructions for blades so using the 2 I should be ok , I wish to set up a Jig and use one of the new fancy Irwin ultrasharp saws, take my time , and hopefully do a good job.

[klsmurf]

Strangely I have not in general found carpenters to be the best people to make blades, a good carpenter will be able to make anything from wood, but the concept is quite different from what they normally do and you will have a job explaining the marking out process.

LOL  Hey, I resemble that remark! I've found this to be true also. I took a laid out 3 ft. blade and a rough cut one to work one day, and most of the fellows couldn't figure the markings out until I showed them the cut out blade. I've done cabinet making also and there's the guys that can make blades.