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Mertz
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| Posted: 05 April 2008 at 6:14am | IP Logged
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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.
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Gizmo
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| Posted: 05 April 2008 at 9:28am | IP Logged
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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
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GWatPE
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| Posted: 05 April 2008 at 9:45am | IP Logged
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Mertz wrote:
| 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. |
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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.
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Mertz
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| Posted: 06 April 2008 at 2:06am | IP Logged
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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.
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Highlander
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| Posted: 06 April 2008 at 6:09am | IP Logged
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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.
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GWatPE
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| Posted: 06 April 2008 at 10:01am | IP Logged
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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.
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Mertz
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| Posted: 08 April 2008 at 1:00am | IP Logged
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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.
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GWatPE
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| Posted: 08 April 2008 at 10:33am | IP Logged
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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.
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Mertz
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| Posted: 09 April 2008 at 1:02am | IP Logged
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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.
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Mertz
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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.
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ABinBoston
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| Posted: 15 April 2008 at 6:34am | IP Logged
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can you tell us what brand and model the booster you used was?
Thanks! - AB
Mertz wrote:
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. |
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Mertz
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| Posted: 15 April 2008 at 8:06am | IP Logged
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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.
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