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Forum Index : Windmills : Voltage booster
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Mertz Newbie  Joined: 03/04/2008 Location: United StatesPosts: 15 |
I am running 2 generators, one using an Indiana 24v and the other an Ametek 30v. The Ametek will spin in very light winds producing some voltage. I can have both turning in 6 to 8 mph winds which are very common in my area. The problem is that they don't get up to 12 volts so there is no charge to my batteries. I eventually want to connect to the grid and but the inverter I found has a minimum voltage of 24 volts. Has anyone had any experience with a voltage booster? I am thinking about connecting it to the Ametek to get the higher voltage and using the high amp producing Indaina for the power at lower voltage. My theory is that there will be both higher voltage but lower amps from the Ametek (sacrifice the amperage to get the voltage) and using the Indaina as the primary generator to develop the amperage. So if the Ametek is producing 15.5 volts and the Indiana is producing 8 amps that would be 124 watts of usable power to the batteries at low wind speeds so I would be producing power most of the time the wind is blowing. Now they spin but are both under 12v most of the time. Mertz |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5116 |
Hi Mertz What if you connected the windmills in series? Would that work? Another option could be to use a little boost converter, like the one from Oatley Electronics, a K091A. It will convert 8 volts to over 14 for charging 12v SLA batteries. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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GWatPE Senior Member  Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi Mertz, You only have 6-8mph winds. My rough estimate would be about 2-3W per sq metre of blade area as output in an alternator at this windspeed. I do not know how you get the 124W, maybe 8 x 15.5? I wish it was that simple. My windmill still puts amps into my 24V battery even though its output is < 15VAC for much of the time. I use a boost type topology that I designed for my mill. I am not in a position to offer specific advice for your equipment. I would suggest that the windmills you have are working correctly, but you do not have enough wind. They were designed to operate in more wind. For a well designed mill of say 2m dia rotor, at the 2.5-3 m/s windspeed, I would expect an output of < 8W. Calculate the rotor areas of your mills and do a comparison. I expect the value you get will be much less than 124. Cheers, Gordon. become more energy aware |
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| Mertz Newbie Joined: 03/04/2008 Location: United StatesPosts: 15 |
I have enough winds to get better performance but I have most constant winds at 6 to 8 mph and would like to use that as much as possible. It is a shame to watch my generators spin and not produce anything useful. I know I am providing amperage to the batteries but they are very slow in charging unless I get to 12 volts. I found a booster that can be set a various voltages. I intend to hook it up as I described and see what happens. I will report back when I get some results. I had the mills hooked up in series but didn't work well since they are of different capacity. Mertz |
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Highlander Senior Member Joined: 03/10/2006 Location: AustraliaPosts: 266 |
G'day Mertz, your probably aware of this but just checking. Did you series connect them in ac or dc? If you do it in ac it won't work unless they are perfectly in sync which is highly unlikely. Be carefull of a volt booster, does it have overvoltage protection? If your mill gets upto speed and starts producing higher voltages you may have a problem. Central Victorian highlands |
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| GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi Mertz, I suggest you look at a wind energy v windspeed graph. This will give you an idea of the available enrgy. Remember that there is a cubic relationship between the energy and the windspeed. Only about a third of the calculated wind energy can be extracted by the turbine. Do you know if the turbine blades on your machines will be efficient at the low RPM? I think you will find that a commercial voltage boost cct will tend to stall your windmill, as there will be output voltage regulation, or input voltage tracking, control. This is not the energy distribution of the wind. I have found that the low windspeed portion of the wind envelope requires a large capture area turbine to produce a useful output. At less than 4m/s windspeed it is only useful to have the windmill spinning, in anticipation of capturing the stronger gusts. I do harness the 1-10W wind energy range. Commercial equipment even with a maximising function tends to cover the 10W and up. DIY F&P enthusiasts have made marked inroads to modifying the original design to overcome some of the low wind and startup deficiencies. You may be able to consider rewiring of your machines to increase the voltage output. The maximum output will be comprimised, but from your description, this may not be as important. cheers, Gordon. become more energy aware |
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| Mertz Newbie Joined: 03/04/2008 Location: United StatesPosts: 15 |
My series connection was a DC connection but I didn't have the blocking diode installed so one gennie turned the other. Both units have different power. The Indiana will generate twice the amps in the same wind but the Ametek spin more often. Good point about stalling the mill. The Ametek30 is difficult to stall. I am currently using 2 blades but have a 3 blade wood prop ready to go on. The Ametek spins and produces 3 to 4 volts in a 2 to 3 mph wind connected to a set of 12 volt batteries. The Indiana will also produce 3 to 4 volts but needs a sightly higher wind to start spinning. It has 3 blades but needs a bigger vane to get it turned into the wind at slower wind speeds. Even with the booster there still would not be any load on the mill until it hits the 12 volts isn't that correct? So if I am producing say 5 volts and boost it to 10 it will still spin easily until it goes to 6 plus volts and therefore boosted to 12 plus volts creating the load on the battery. Is that a correct assumption? I can set the booster to different voltage outputs and will have a charge controller to dump the voltage should it go higher than 14.1 volts. The higher voltage won't be a problem once I get off the batteries and on to the grid tie inverter. It will accept much higher voltaqes. I am not sure if the booster I am getting is regulated output, some are. I really don't care if it is regulated since I want to get as much voltage as I can from the low wind speeds. Mertz |
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| GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi Mertz, the set voltage boost you are describing will bring the cut in speed down, but the manufacturers design will be drastically changed. Without some power controlling means, you will notice that the windmill will produce much less power at the top end with a commercial set voltage boost cct. This is like the problem F&P DIY'ers have, trying to match stators and rotor speeds to a battery system by rewiring etc. You have basically a system that is designed for moderate winds and charging a 12V battery, and your requirements seem to be a low wind design for 24V system. You may be able to incorporate a voltage boost cct with a series resistance. This has been suggested by "flux" from "otherpower" forum. This will reduce the effective mill load as the windspeed increases. check this option, and it may help, Gordon. become more energy aware |
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| Mertz Newbie Joined: 03/04/2008 Location: United StatesPosts: 15 |
Good points but I am essentially sacrificing the Ametek for the voltage and using the Indaina for the power. I will be hooking up the booster only to the Ametek before my parallel connection. If I only had one generator than this would be a serious issue. Since I have the unit coming the best thing to do is install it and see what happens. I will report back for everyones information. I intend on leaving everything else as is until I get the results and then I will be changing blades to the wood ones I built for the Ametek. Mertz |
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| Mertz Newbie Joined: 03/04/2008 Location: United StatesPosts: 15 |
I hooked up the booster over the weekend and am now reading 13 plus volts on my Ametek even in light wind. The input voltage at 2.77 has an output voltage reading 13. I have is set so that it will go up to 13.20 with the batteries connected. The Indiana is producing about 7.8 while the Ametek is at 13.20. In theory I am inputing the 13 volts from the Ametek and the amperage from the Indiana. I am very please with the results. Next step grid tie inverter. Mertz |
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| ABinBoston Newbie Joined: 06/04/2008 Location: Posts: 2 |
can you tell us what brand and model the booster you used was? Thanks! - AB |
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| Mertz Newbie Joined: 03/04/2008 Location: United StatesPosts: 15 |
It was one I got from ebay. It is a 12/24v converter. Price was $40 If you can't find it let me know. I don't have access to ebay here so I can't send the link. Mertz |
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| GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi mertz, The windmills from your descriptions are a permanent magnet generator with a mechanical brush type commutator. I have been unable to find details on an Ametek, or Indiana type windmill. Do you have any details on power rating or blade rotor dia, etc? The voltage figs you have mentioned would only be useful if rpm was also given. What power rating is the DC-DC converter? It appears to be an output regulating converter from the details you have given. Does it have current limiting? A voltage boost maximising cct on both windmills would still probably be a better solution. .. Gordon. become more energy aware |
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| Mertz Newbie Joined: 03/04/2008 Location: United StatesPosts: 15 |
First of all I am not an electrical engineer. The electrical part of building the windmills has been the most challenging for me. I understand the basic principles but beyond that I get lost. Both my generators are permanent magnet DC probably brush type. The Ametek 30 has become the standard for small wind turbines since the Ametek 99 is now very hard to find. I found the Indiana on the web and the guy that sold it to me did a comparison test on it versus the Ametek30. It can be found at http:windpulse.com/AmetekData.html You will see that the Indiana is about twice as good as the Ametek. I am using 5 foot diameter blades with 3 on the Indiana and 2 on the Ametek. The Ametek spins easier and usually spins much faster than the Indiana. I need a better set of blades that are a little faster for the Indiana to maximize its power. We had 13.1 mph average winds yesterday. When I checked the system in the evening the Ametek approached 14v and the Indiana varied between 10 and the high 13s. My battery bank voltage had gone from 12.36 in the morning to 12.96 in the evening. The information I got with the booster indicated that it was regulated voltage. It does vary some when connected to the battery. Everything seems to be working just as I wanted it. I have controlled voltage to the batteries and will normally have at least 13v delivered by the Ametek and the amperage delivered by the Indiana. Nest step is to get my grid tie inverter. A 12v inverter would be best but I have a 24v inverter I can get for $300 that will work. No batteries required which should increase my voltage to the inverter. Mertz |
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| GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi mertz, I was led to believe that your windmills were commercial units. Not so! ... Gordon. become more energy aware |
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| Mertz Newbie Joined: 03/04/2008 Location: United StatesPosts: 15 |
No, they are hand made. I had a lot of fun building them but got really frustrated trying to use the power. I wanted to power my stock heater in the shop using a 2000/4000watt inverter but that didn't work. So now all I am doing is charging my RV and a couple of car batteries. I ran some Christmas light this winter after rigging them for 12v. I ran them directly of the generator so the got brighter as the wind got faster. It was kind of fun. I have spent a lot of time doing reseach and trying to find a reasonably price grid tie inverter that will work with my system. After that I can just let them fly with just regular maintainance and some tuning of the blades. Mertz |
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| GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi mertz, You should calculate the energy your windmills can expect to harness. I am sure that you will not be happy to see how little energy these windmills will harness in the low wind conditions you have described.... Gordon. become more energy aware |
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WineGuy Newbie Joined: 16/04/2008 Location: United StatesPosts: 10 |
I'm kind of confused here (I'm a newbie, you have to expect things like this). I was under the assumption that the gen produced no power until the gen voltage output was higher than the battery voltage. So the Ametek will produce power before the Indiana. Mertz wrote: In theory I am inputing the 13 volts from the Ametek and the amperage from the Indiana. This sounds like comparing apples to oranges. If the Indiana is not above the battery voltage, does it still provide amperage even if the Ametek has high enough voltage? I thought they would be independent of each other, almost operating in parallel. Point of confusion #2 With a voltage booster, doesn't the current drop proportionately (power in = power out)? Sure wish I was smart instead of so darn cute! |
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| GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
I believe that the two units are to be run in parallel. I have been trying to read between the lines as well. Here are the data specs from the above link. These are apparently open cct volts and short cct amps at the various RPM. I am not sure how much value they are for determining power output as a wind generator. Indiana 24vdc RPM Volts Amps 100 6.12 1.64 200 12.24 3.28 300 18.36 4.93 400 24.48 6.57 500 30.60 8.21 600 36.72 9.85 700 42.84 11.49 Reaches 14 Volts at 229 RPM Ametek 30vdc RPM Volts Amps 100 3.36 1.00 200 6.71 2.00 300 10.07 3.00 400 13.24 3.95 500 16.60 4.88 600 19.92 5.85 700 23.24 6.83 Reaches 14volts at 423 RPM I hope this data helps someone. .. Gordon. become more energy aware |
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| Mertz Newbie Joined: 03/04/2008 Location: United StatesPosts: 15 |
My theory here is that the Ametek is producing the 13 volts needed in the parallel circuit so when the generators come together they are producing over 13v and although I am not getting any amperage to speak of from the Ametek I am getting the full amperage from the Indiana. The unit is attached to the output of the Ametek before the parallel so it has no effect on the Indiana. I have multimeters connected to the output for both generators and the output from the combined connection to the batteries and it proves out the theory. This unit is probably meant to get a constaint current applied to it so I am not sure how long it will last under the varied supply of a wind generator. It has been up and running for several days now in 13 mph winds with gust to 32. So far no problems. Mertz |
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