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PostPosted: Sun Jan 13, 2008 11:19 am
by jongwitman
This is an awsome site. I would love to try this wind generators. I am an electrician so I have some knoledge of what you are doing. What about using a 12v car alternator with this wind turbine? Your drawings aren't to clear , where on the site can I search for detaild plans on building such a wind turbine? I want to use it to charge deepcycle batteries and then power some lights and my tv and dvd. I will use an overvoltage relay to switch the turbine from charging to shortcircuit at 14.1 volt and back to carging at around 12.5 volt.
I would appreciate any advice .
Ps . Have you thought about building and selling your turbines?


Re: alternator

PostPosted: Sun Jan 13, 2008 5:51 pm
Hi jongwitman! Yes, I also think windgat should make up his wind charger etc. in a kit form for those who do not have all facilities to make their own!
I am also an electrician/electronics technician and it seems that we are beginning to gather birds of a feather on this forum. We should not do what our forefathers did, namely keep everything to themselves. We should genuinely share ideas and resources where we can. We cannot afford to be held hostage any longer by authorities who did not do their homework (planning expansion of our electricity generating capacity). Now WE have to pay more for electricity in order to subsidize their bad planning. What happened to good old long-term loans from abroad? Enough said!

Regarding your question on the use of a car alternator: 1) It needs excitation from a power source and you are trying to generate power;
2) An alternator has a fair amount of "cogging", i.e. it is difficult to turn with the excitation on, something which is bad for start-up of a wind turbine.

At first, I thought the guys didn't know what they were doing, because I could not see the usual iron core for the coils as we electricians are so used to! Only later did I find out that the magnets that they use is nothing that I was used to in the past! Indeed very powerful ! This means that without an iron core in the coils, there still is enough flux to generate power in the coils as the magnetic rotor sweeps past them. This also has the effect that you don't have "cogging" and the turbine speeds up until it reaches cut-in speed and generates power.

A car alternator could be used with a slow speed, high torque turbine with multi-blades or a big Savonius vertical turbine by using gears, belts & pulleys, but with greater losses and you'll have to over design.

Re: alternator

PostPosted: Sun Jan 13, 2008 7:09 pm
by jongwitman
Thanks jtech
Ja dit maak sin . Ek verstaan nie al die groot ingelse terme wat jy gebruik nie maar ek weet dat an alternator ge exite moet word. My idee is om lekker groot deepcycle batterye te gebruik en sterk inverters. ek wil die ding so koppel dat ek op altwee my karre plugs onder die voorbumper sit , en dan waneer hulle by die huis is ook inplug by my sisteem. So. Kom ons se ek het 1000ah deepcycle batterye en my twee kar batterye wat gelaai word deur wind en dalk deur son . dan kan ek my ligte en tv ens van die inverter af laat werk. My stiefpa gaan nou sy geyser met ou olie en solar energie laat werk. Ek weet die brand van olie stel weer gasse vry maar dit is net om die solar aan te help. Ons het n stalasie gebou met ou geyser tenk onder het ons solide staal stawe ingesit wat ons met n olie burner verhit die olie word gereguleer met n solenoid en termostaat. Ou olie kos so 10c per liter as jy dit moet gaan koop maar ons kry honderde liters verniet so olie maak sin .
Agter my ma se huis is n water stroom wat kom van n fontein en daar wil ons n waterwiel bou.
die stroom gee so 200 - 300 liter per minuut . sal hierdie tipe gen. werk? is die formule vir potensieele energie van die stroom reg as ek se : hoogte(head) x vloei (l/s) x gravity (9.8)?
Dit beteken dan dat die stroom maar net 40 wat het want die maks head wat ons sal kry is so 1 m.. Ek gaan maar sukkel om al die goed te kry vir so n gen hier in kimberley so sal graag will hoor of julle so iets in kit vorm of geheel sal verkoop.

Thanks eers

Re: alternator

PostPosted: Mon Jan 14, 2008 3:35 pm
Hallo Jongwitman,
Ek is nie seker of ons toegelaat word om in Afrikaans te kommunikeer nie, want dan kan die res van die wereld nie deelneem nie! (I will gladly translate this if requested by anyone.)
Hier is 'n "link" na inligting oor waterkrag:

Sterkte en laat weet wat julle alles aanvang met alternatiewe energie.

Re: alternator

PostPosted: Mon Jan 14, 2008 4:27 pm
by windgat
Hello Ouens! Nothing wrong with Afrikaans! Perhaps we can try and be international and use English, but anyone is welcome to express themselves is the language of their choice. Using English of course has the advantage that there are more people out there who could help you - Australia, USA, England etc.

Jong - be careful when connecting the car batteries to the other battery bank as you describe. This can result in a brief huge surge of current from the charged to the uncharged batteries, which can damage the batteries and wiring. Hopefully you will install fuses! If so, they are sure to blow if the (differently charged) batteries are connected directly to each other.

I think you need more height to make the water wheel worthwhile, 40W is very little. Could you run a pipe upstream?

I am happy to make parts to order, especially the stator which I have made coils winders and jigs for. Let me know what you want and I will let you know what the parts would cost.

Re: alternator

PostPosted: Tue Jan 22, 2008 9:26 am
by xgth
Hi all

My first post, and a great site I might add!

A note on using a car alternator for wind power generation... a car alternator only starts producing worthwhile electricity when turning at about 1500 rpm. You will probably need a 1:5 gearing system to make this worth the effort with a wind turbine... This introduces lots of other problems, specifically- energy losses when using gears or pulleys ;-)

Also, re using car batteries coupled to an inverter... not a good idea, especially not for long periods, since car batteries are not designed to be deeply discharged and then recharged numerous times.


Re: alternator

PostPosted: Tue Jan 22, 2008 10:34 am
by windgat
Hi and welcome X! Yes lots of people start by looking at the alternator idea... it might work with short blades (which allows high rpm), but of course that means less wind is caught and so power is very low. Gearing as you say is a whole other issue, including noise!

To prolong battery life, a cut out circuit should be installed which stops all current when a 12V battery drops below 12.2V. Deep cycle batteries have thicker plates, and so should last longer when deeply discharged. I bought 'high cycle' batteries recently, which are apparently somewhere between deep cycles and standard car batteries. I still need to install a low voltage dropout (LVD) circuit, and so for now I monitor the battery voltage manually.

Re: alternator

PostPosted: Mon Feb 04, 2008 8:15 am
by Jeannette Unite
Can anyone build one of the wind energy systems for me and how much would it cost?

I saw the wind turbines in the harbour near Copenhagen which were beautiful and less offensive noise wise than a car motor.

I am hoping to build a studio outside Cape Town where I can fire glass (ceramic) kilns and I would like renewable energy on the site

Jeannette Unite

Re: alternator

PostPosted: Mon Feb 04, 2008 10:42 am
by xgth
Hi Jeanette

Maybe you'd be better of with a commercial unit?



Re: alternator

PostPosted: Tue Feb 05, 2008 9:10 am
by forum_admin
Query from Jeanette moved to 'General' forum


Re: alternator

PostPosted: Wed May 14, 2008 4:35 pm
by frans
If you want to go the Alternator route, DK Enterprises has a nice plan with metal blades (I dont like) and an Alternator. If u cant find the site email me and I will send u a copy. I am also in C Town so maybe can drop it off.
If you do decide to build please post photos for us and tell us how well it works. Good Luck, Frans

Re: alternator

PostPosted: Fri Dec 12, 2008 11:35 am
by Jan
Goeie dag.

Ek en my kolega wil 'n wind terbine bou op sy plaas in Namibiƫ. Ons gaan dit basis uit 'n windpomp bou en dan die ratte uit die kop haal en 'n pully gebruik wat op sy beurt 'n alternator draai. Wat sal die verkieslike spoed wees waarteen die alternator moet draai?Dit sal 'n 24V 145Ah alternator wees. Wat sal beter wees, 'n 12V of 'n 24V alternator? Enige raad en voorstelle?

Re: alternator

PostPosted: Mon Dec 15, 2008 12:31 pm
by windgat
Hello Jan. You should test the alternator by spinning it with a motor (or electric drill). Measure the RPM, perhaps by using a bicycle speedometer, and see how fast you need to spin it to get 28V (for a 24V system). This will be the minimum speed to aim for. For 12V, aim for 14V. Then you can measure the RPM of the turbine in a typical wind speed, and work out the gearing ratio you will need from there. Of course under load the blades will turn slightly slower.

24V allows more power and thinner cables - power loss in the cable is P = I * I * R. Windpomps usually have many flat blades, called 'push' blades, which generate high torque but lower power. Typically they can capture about 15% of the energy in the wind. That's why most turbines use 3 blades which are designed a bit like an aircraft propeller and use lift. They also turn faster so gearing is not needed, and can capture a larger percentage of the wind energy, well over 50%.

When you say 145Ah I assume you mean 145A. That's a lot of current, and if you get anywhere near that you will need very thick cables.

I would suggest you test the alternator extensively on the bench (see the 'Benchtesting' page on the website) before putting it at the top of the tower.

Good luck with your project!