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Forum Index : Windmills : 12V 900W Turbine - Splitting the Load Over 2 Controllers?
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Technophiliac Regular Member  Joined: 18/12/2020 Location: New ZealandPosts: 92 |
I am installing a 12V 900W (max) turbine. Most Chinese commercial controllers are rated for a max of 500W at 12V. I was thinking is there any reason I cannot run two 12V 500W MPPT controllers each with their own dump load in parallel to split the current and take the load? Seems to me a reasonable thing to do if the 3 phase AC cable runs are symmetrical in cable size and length to feed the 3 phase AC side of each controller, with each controller connected to the same 12V battery bank. Anyone able to comment would be appreciated! Davo, Wellington. You can have it perfect, on time, and at the best price. Choose any two. |
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| Warpspeed Guru  Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
What makes you so certain they will split the current and load share ? The two MPPT systems may just as easily fight each other. One system draws more power, pulling down the source voltage. The other system says Oh! the source voltage is dropping, I will reduce the loading. So one system goes to max, the other throttles right back. No real way of knowing what will happen, but your chances of getting perfect load sharing are just about zero. Cheers, Tony. |
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| Technophiliac Regular Member Joined: 18/12/2020 Location: New ZealandPosts: 92 |
Hey Tony, many thanks for your thoughts. Yes I worried about that, hence the post. What if I used 2 x 500W PWM controllers to get the necessary capacity? Davo, Wellington. You can have it perfect, on time, and at the best price. Choose any two. |
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| Kamak Senior Member  Joined: 13/04/2021 Location: CanadaPosts: 150 |
It might be possible to find two reasonable power rated 12V Buck converters (1500W 30A DC-DC Boost Converter Step Up Power Supply Module Constant Current ) in parallel with current limiting capability, then in series with your 12V 500W MPPT's |
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| Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578 |
I would suggest the chances of getting over 500w from your turbine is minimal. Exactly what is the make and model of the unit you are going to be using? |
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| Technophiliac Regular Member Joined: 18/12/2020 Location: New ZealandPosts: 92 |
Not sure why the scepticism, for example what capacity do many car alternators have? 12V 800W Smaraad F-800M5 aka SM5-800 (Made in China) I cannot verify who the manufacturer really is but it may be this company. Davo, Wellington. You can have it perfect, on time, and at the best price. Choose any two. |
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| Technophiliac Regular Member Joined: 18/12/2020 Location: New ZealandPosts: 92 |
To give you even more fuel for scepticism here is also a 12V 1000W Smaraad F-1000M5 aka SM5-1000 but even 800W is currently more than I can handle. These are a step up from the lower powered single mould units commonly seen. Its the smallest generator package I could find in the design I wanted. And for your Crocodile Dundee "Now that's a knife" moment:  Davo, Wellington. You can have it perfect, on time, and at the best price. Choose any two. |
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| Technophiliac Regular Member Joined: 18/12/2020 Location: New ZealandPosts: 92 |
Anticipating the next question, why 900W, the 800W unit is said to peak at 900W and the 1000W similarly peaks above that. To start with I'll run under size blades to limit the power (and lessen the spin time too....I know) Back to the original question: One option might be to use one 500W controller (with its own dump load) and make a AC 3 phase side Dump Load voltage sensitive hack and look to limit the power thru the controller that way. Dump load options are standard ceramic dump resisters, Oil heater elements or PTC heating elements. Davo, Wellington. You can have it perfect, on time, and at the best price. Choose any two. |
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| Kamak Senior Member Joined: 13/04/2021 Location: CanadaPosts: 150 |
I'm pretty sure two DC-DC buck converters will do the trick for you. They will divide your total gen output by maintaining output voltage, throttling, and maintaining constant current to both your 500W MPPTs. |
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| Technophiliac Regular Member Joined: 18/12/2020 Location: New ZealandPosts: 92 |
I did find some like you proposed but they were only about 300W each from memory at 12V (higher wattage at higher volts...). My observation of solar MPPT's is they disconnect from the panels at regular intervals and let the panels "spin up". Not entirely sure why they do that, I suspect its a necessary part of the MPPT logic, someone here will know, but if / when a wind MPPT does the same there is going to be excess power running around == a turbine spinning up which might not be such a good idea, as I understand it its not a good idea to have them freewheeling when the power's up running in high winds. Maybe that's not an issue if the wind controllers divert power to the dump instead, which would make more sense to me. Elevator pitch: DC-DC buck Converters may well protect the controllers but at the expense of the turbine? Davo, Wellington. You can have it perfect, on time, and at the best price. Choose any two. |
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| Technophiliac Regular Member Joined: 18/12/2020 Location: New ZealandPosts: 92 |
I need to get it running on small blades and see what the controller is actually doing. If they do maintain the load and I can find some 500W DC-DC buckies I might give it a go. Or 3 x 300W Buckies and 3 controllers might work..... Starting to become big bucks! But maybe a good option. Davo, Wellington. You can have it perfect, on time, and at the best price. Choose any two. |
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| Technophiliac Regular Member Joined: 18/12/2020 Location: New ZealandPosts: 92 |
Doh, but wait a minute, are you suggesting I place the DC-DC buck converters between the turbine and controller? That section is running 3 phase AC.... Davo, Wellington. You can have it perfect, on time, and at the best price. Choose any two. |
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| Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578 |
Because nothing I have read or seen of these things has confirmed ther stated output. Looking on fleabay I see ridicilously exaggerated claims for these things. 3000w and selling for $149. If I thought they had a hope in hell of doing that I'd (and im sure others would too) buy a couple and put them on a diesel engine to make a generator. Looking at many ads i see things like a claim of 3000w peak, 1000w constant. Have enough experience with Chinese seller lies no to see these red flags. A 80a car alt will do around 1000w. Knowing the power, speed, cooling and size of the units makes me extremely suspect on the ability of these turbines to come close. Have you looked at the windspeed these turbines need to make the claimed power and compared it to what you get in your area? Id waget that a 25% reduction in wind speed results in a 50% at least reduction in output. Be interested to see how you go with this but wont hold my breath with you gettingnmore than 2-300w out of the thing. Might be worth looking at backing up with some solar panels. |
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| Technophiliac Regular Member Joined: 18/12/2020 Location: New ZealandPosts: 92 |
 Yep indeed solar panels are of course being looked at to complement. I've only set out the tip of the iceburg problem, not the whole evolving plans. I've recently commented in this forum about buyer beware and I of course agree much care is required in the selection of products purchased with Wind Turbines a case in point. The wind here varies like everywhere with the expectation that power generated will be a function of wind speed (in simple terms). Average wind speed might be over 6 m/s with occasional peak of 20 m/s. IMO that will test the maximum available output and we will see - when I get a backend to cope with a full propellor install of 2.2m diameter that is.... I am yet to test this kit so maybe the first 15 m/s gust blows it up. I'm going to find out - maybe Davo99 you'll get the "told you so" spot. Happy to share results in due course - if anyone is interested. Davo, Wellington. You can have it perfect, on time, and at the best price. Choose any two. |
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| Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578 |
I hope you can say that! Best outcome for you and i will have learned something worthwhile. Also nice to learn about good chinese products in the midst of what I can tell are a lot of rubbish just by the specs. I'm not against chinese made things, there is just so much crap and to be honest, the Chinese sellers are farking liars with so many things. In their culture, it not on them to tell the truth, its on the buyer to figure out the truth. I just bought my father some new chinese made toys. The biggest wood chipper and flail mowers they make. Both are VERY well made and solid beyond our expectations. Lot of nice, well thought out touches and minimal shortcuts. So far with the few hours work i have done with them i think they will last a good long time... like the other chinese machinery he, myself and a friend has an extensive range of and have had zero trouble with for many years despite flogging some of it mercilessly. For whatever reason, seems so much of other china products are over hyped, inferior crap no matter what the price. Electronics and electrical seem the polar opposite in quality to the machinery. Just the specs on these turbines makes me question their quality because they are literally defying physics. In comparison, the machinery seems to not only live up to but exceed what it is advertised to do. I hope your turbinebworks out the same. Id love to put one on an engine and sin it up to test their claimed ratings...only if someone else was buying the alternator because i have no confidence in them. Certainly interested in how you go with it and do hope you can prove my suspicions unfunded. |
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| Technophiliac Regular Member Joined: 18/12/2020 Location: New ZealandPosts: 92 |
 That's for you to say, I doubt you'll see that from me!Curiously these are marketed as "Real 800W" turbines. I'm a gonna find out!  Davo, Wellington. You can have it perfect, on time, and at the best price. Choose any two. |
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| Solar Mike Guru Joined: 08/02/2015 Location: New ZealandPosts: 1138 |
Technophiliac, I have done some research looking at various smaller vertical turbines, this one is interesting, it appears to be quite well made, bit pricey to get to NZ; Power output curve is similar to yours, if it can be believed. FX-600  Regarding a suitable controller, seems easiest use an off the shelf suitable sized mppt controller from another bigger turbine, rather than attempt to get multiple ad hoc controllers to load share. I will be designing one and publish details on the forum, but will be awhile away. Cheers Mike |
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| Technophiliac Regular Member Joined: 18/12/2020 Location: New ZealandPosts: 92 |
Indeed Mike. As I've previously said you get what you pay for. By serendipity I have a 48V FX-800W awaiting installation to also try, they tell me its the only one sold to NZ! There are two versions to this(!) The publicly promoted small one, and the larger "real" 800W one. (I confirm no typo here) Why they do it like this I really cannot fathom. Maybe someone can suggest? (Why wouldn't you promote your best products? My best guess is its about the development of relationships first?) The generator component appears of similar quality to the picture of the above 12V generator. The bearings have no discernable play for what that's worth! Who knows how long they will remain like that but its a good start. The generators can also be bought separately. I speculate you may find it difficult to do better than one of those as the generator component for your custom home vertical turbine but respect you may wish to exercise your skills and I cannot yet vouch just how robust these things are. I understand they run slower than horizontal turbines, are purportedly quieter, are less efficient (a little) but may make comparatively more power in lighter winds. Also their blades may not last as long as the horizontal competitors. There, you sort of asked! Where are you in NZ? I am yet to find an economic commercial 12V Controller with separate Dump Load specified to run @ 900W. Can you point me to one? Quite a few are stated to run to 500W / 12V or at higher voltage wattage's. How faw away is "awhile". Months? Weeks?? (Optomistic look!) Davo, Wellington. You can have it perfect, on time, and at the best price. Choose any two. |
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| Technophiliac Regular Member Joined: 18/12/2020 Location: New ZealandPosts: 92 |
I think I'll use some dump loads summing say between 200W and 500W on the AC side with volt sensing SSR control and use a 500W controller as well. Effectively the controller will get what power is left over. Could use an AC 3 phase SSR with 3 dumps of say 150W a piece or It may seem better to rectify the 3 phase to DC and run dumps across that, that way I can step the dump loads using more than one voltage sensor to control multiple DC SCRs. A third option might be to run say 3 x 3 phase AC SSR's to their own rectifier to a smallish dump load of say 150W each and progressively switch these in as needed (Effectively 3 AC SSR / Rectifier / dumps in parallel switch in at different voltage levels). The economics of parts and safe capacities may determine the economic option! Any one? Davo, Wellington. You can have it perfect, on time, and at the best price. Choose any two. |
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pollenface Regular Member Joined: 01/09/2020 Location: AustraliaPosts: 47 |
I have the 1000w boost/mppt controller from ebay $65AUD. It works, but my turbine has never produced more than 225w in a single instance. Off grid man caver |
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