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Forum Index : Windmills : 500W 24V to charge 12V system
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wallablack Senior Member  Joined: 10/08/2011 Location: AustraliaPosts: 164 |
I have a Chinese 500W 24V turbine sitting in the shed and am thinking of using it to charge my 12V shed batteries. I DO NOT want to change my battery configuration as everything on it is 12V. I have trolled the internet and have mixed reports of doing this. What is the easiest way to achieve this? Foolproof systems do not take into account the ingenuity of fools. |
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| charlie_ruizpr Newbie  Joined: 08/07/2010 Location: Posts: 36 |
I was planning on doing the same thing and I was recommended from other members to us a step down converter mostly found on ebay. |
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Downwind Guru  Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
Perhaps someone can tell me what the difference is with a 24v windmill to a 12v mill, as most of the chinese ones use exactly the same generator for all their voltage ranges.(12, 24, 36, 48) Its just the cutin voltage to RPM that changes. Your best option would be to change the stator wiring from star to delta for a 12v mill and that should solve the problem. There is no reason the 24v mill wont work at 12v as it is, its just it will be loaded very heavy, and may struggle to get out of stall. Sometimes it just works |
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yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
it is all going to depend on how the turbine is built and wired. check any documentation that you can find to see if they list a cut in RPM for 24 volt. Grab a multimeter and measure the AC voltage across two phase wires as you spin it over by hand on the bench with no battery connected. this will give you a number to work with that will be close to the dc output voltage after the rectifier. If it hits 10 volts under 35 RPM it is probably wired as a high voltage generator, it will be tough to get rolling. 50 to 120+ RPM would be ideal for a bigger set of blades and should bolt straight up with a suitable rectifier regulator and dump load. I would scrounge the rectifier pack and diversion load from the 24 volt controller and invest in a morningstar TS-60 controller or something similar. I have a 12/24 300 watt 5 foot chinese on the bench now. I just gave it a spin with a socket on the cordless drill and it was on 12 volts at about 230 RPM. It runs pretty sweet and knocks out good amps in light winds as a 12 volter. I am guessing here, but measuring two wires AC, 8.5 to 9 volts would be close to 12.? volts DC after a rectifier pack. So measure/guess the revs at 8.8volts and that should be close to the point where it starts to charge a 12 volt battery. If the insides look anything like the one I pulled to pieces earlier this year chinese anatomy then swapping the wiring configuration will be a challenge, it is not wound like a standard 3 phase motor. I'm confused, no wait... maybe I'm not... |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
I agree. That will definitely work, it will decrease the output voltage, and increase the output current capability. Another practical alternative would be to separate the three windings entirely, and feed each winding into it's own four diode bridge rectifier, and then parallel the dc outputs of the three rectifiers. The results will be pretty much the same either way, but one solution may prove easier or more convenient to do than the other in individual circumstances. Cheers, Tony. |
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| MickWh Newbie Joined: 08/05/2010 Location: Posts: 19 |
Out of interest would it be possible to go the other way around, 12V turbines are cheaper than 24V, but my battery system is 24V. |
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| Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
It all depends on the alternator construction and if you can access the windings. Also 12 volt at what rpm? because if the turbine dont have internal voltage regulation and is capable of running at a higher rpm then 90% of the time simply doubling the rpm will double the output voltage......IE- 100rpm cutin at 12v will be close to 200rpm cutin for 24v. A lot of turbines have the same windings just run at different rpm for different voltages and/or wired in star or delta, for which ever better suits the voltage range. Check out the given rpm to volts of the turbines you consider buying and often the rpm goes up with the rated voltage. If you want a good Chinese 24v mill then contact Phil for one, as they are proven to work. Sometimes it just works |
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| wallablack Senior Member Joined: 10/08/2011 Location: AustraliaPosts: 164 |
The Chinese manufacturers specifications are in: Power Output: 500W Min up to 5Kw Maximum. Best Feature: Highly utilized technology that "auto-detects" and "auto-adjusts" so your system voltage no rorries. Slip Rings: Yes (this is no in thier language) Blades: 19 Carbon Fibre Composite Blades. (Actually fibreglass but it has fibres so it must be carbon fibre) Foolproof systems do not take into account the ingenuity of fools. |
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