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Forum Index : Windmills : DC 130v 2 1/2 hp DC Motor
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asvin bahadur Newbie  Joined: 29/07/2008 Location: MauritiusPosts: 21 |
hi everyone, i have just purchased this DC motor(DC 130v 2 1/2 hp Permanent Magnet MOTOR, WIND GENERATOR) from Ebay and i am not very happy with it. it is very hard to turn because of the carbon brush and it cost me a fortune and i don't think i will be able to use it as a wind turbine. will do some experimenting s during the weekend. already cut out the blades in PVC s. Has anyone out there ever used this type of DC motor for a wind turbine? thank you. asvin.b |
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vawtman Senior Member  Joined: 14/09/2006 Location: United StatesPosts: 146 |
Hi Asvin Do you have a link or pic of the nameplate? Mark |
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| vawtman Senior Member Joined: 14/09/2006 Location: United StatesPosts: 146 |
Oh and another thing if the leads are shorted and that's the reason it turns hard that would be a good thing. 
Not sure of your experience |
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Dodgeman Newbie Joined: 19/07/2008 Location: United StatesPosts: 33 |
I have been competing with you on ebay for a decent dc motor recently
If I am not mistaken, you are describing the "treadmill duty" motor? From my findings, many of the treadmill type motors are rated upwards of 10,000 RPM at 130 volts, from what I have heard/read on the subject, the "rule of thumb" is to quarter (1/4) the input ratings of the motor (from the data plate or spec sheet) to get approximate expected output, (derating by 3/4ths or factor of 4) I forgot which site I read this information on, and have yet to confirm or deny it to be accurate. If, indeed this is the case for dc motor sizing for wind genny use, and you indeed have a high rpm treadmill motor, they very well may not be too suitable for direct drive wind generator applications. From what I understand you should look for a reasonably low RPM rated PM DC motor (like 1725-2500 or so) with the highest current (amp) rating and voltage you can get ahold of. The reasoning behind this "quarter derating" theory suggests that, if you take one fourth of 10,000rpm, and one fourth of 130 volts, you will still require 2500 motor shaft input RPM from your propeller to produce about 32.5 volts. (that will still charge batteries but the RPM, to me, seems still a bit high for a small PVC bladed mill) Using 3-4 ft pvc blades, I would guesstamate about 400-600 RPM at the most ??, in hurricane type winds ??. (I dont know enough math to back that up and it is only a wild guess since I dont own a tachometer capable of accuratly counting the rpms of any of my previous generators, it could be entirely possible and I just guessed wrong.) That would be a -Derating factor- of about 14, or 1/14th of rated RPM, that fourteenth would then be applied to the 130 volt input rating which would net you about 9-10 volts at 400-600 rpm. The motor I got (for about $50 U.S. Dollars delivered) was a 3/4 hp 90 volt pm dc industrial type 56c frame (TEFC) totatly enclosed fan cooled motor. These motors are much heavier and better made than the treadmill duty motors and generally have a higher current rating and much lower (1750 +/-) RPM ratings and are also continious duty motors as where the treadmill motors are intermittent duty, not to mention the sealed ball bearings as opposed to the brass sleeve bushings in the treadmill motors. I could be way off base in my advice to you, but, it the information I have been going by in my search for a permanent magnet motor if you can gear it at all, that would aid in acheiving the higher rpm needed to operate correctly ?? Hope this helps and if you can provide a spec sheet or even a picture of the motor it may help. above all, good luck with your experiments, and keep us posted,,and remember, its all experi-Mental electricity 
Dodgeman |
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| windlight Guru  Joined: 03/03/2007 Location: AustraliaPosts: 331 |
I think he means this one http://cgi.ebay.com.au/2-5hp-130V-DC-motor-Wind-generator-w- Flat-Base-Mount_W0QQitemZ130242013149QQihZ003QQcategoryZ1218 37QQssPageNameZWDVWQQrdZ1QQcmdZViewItem allan "I like this place and willingly could waste my time in it" - (Act II, Scene IV). |
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| asvin bahadur Newbie Joined: 29/07/2008 Location: MauritiusPosts: 21 |
hi everybody, sorry for my late response, the model is the same one as Allan mentioned, only the bracket is different (http://cgi.ebay.com.au/eBayISAPI.dll?ViewItem&item=13024254 6823). Dodgeman thank for your advises and tips. i had to read your mail twice to understand it. just to tell you a bit about my experimentation that i did during the week end. i am actually in the process of setting up a wind turbine. i received most of the equipment that i need for the job, like charge controller, batteries, DC to AC inverter, solar panel, DC motor(s. As mentioned earlier, i have already cut out the blades from an 8" PVC. the blades are each 34" long. all i need to do now is make a tower for the turbine. also i am going to mount the turbine on top of my house. i have already work out the plan for mounting the tower. the main problem is noise vibration which hopefully i am taking care of in my plan. i made some modifications to the DC motor that i have purchased. The motor is so easy to dismantle and i removed the carbon brushes and turned the shaft by hand. As expected, the rotation was more as compared to before. the brushes was causing the shaft to slow down. therefore i decided to modify the springs that push the brushes and making it softer. that way the pressure applied is less and we have more rotation. after mounting the motor, i tested it and it work just fine. i am sure that even in a small breeze, it is going to turn. the only problem now is that the output voltage with this type of motor will be around 5V. I am thinking of using a stepper to increase the voltage or even using two wind turbine. i guess i will have to wait and do some more tests. cheers asvin.b |
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| Dodgeman Newbie Joined: 19/07/2008 Location: United StatesPosts: 33 |
Hello again Asvin, I am sorry about my grammar and I still find it hard to describe some things in a post or two, I frequently find myself rereading many writers descriptions, so dont feel bad 
anyway, I looked into the motor that was posted by Allan as your link did not work or was expired. That little gold motor is indeed, a treadmill duty motor. It appears to also be -continious duty- rated, for its 1.5 hp rating@ 95 vdc so I will use that figure. However, its only rated 6750 RPM and not the 10,000 that I expected, I still believe that without gearing, your 6750 rpm is just a little high when de-rating for wind generator uses. Here is my thinking on the use of that motor For that motor, and my assumed calculations, >6750 devided by a derating factor of 4 is 1687.5. So you will have to achieve 1687 RPM to get a quarter of the 95 volt input rating, as your output or generated voltage. At 1687 RPM you could see 23.75 volts dc without a load, without gearing that motor up with say a 1 to 4 ratio from prop to motor shaft, I believe that it will be difficult to get a useable voltage. Keep in mind that these figures are just one guys best guess, and may, or may not, be accurate. They should not deture you from any experimentation. Please keep us informed of your experiments and let me know what voltages you do actually get when you get it flying. I have yet to fly mine, and take readings either, but soon,, very soon. thanks and good luck. |
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| asvin bahadur Newbie Joined: 29/07/2008 Location: MauritiusPosts: 21 |
Dodgeman, thank you for writing back. i must say you seem a passionate person just like me. the calculations that you gave me sound very reasonable. i will have to redesign the system, taking into consideration that i can not drive the motor directly with the blades and will have to use some kind of gearing like you mentioned to get a good voltage (12V +) to be able to charge a 12v battery. BTW do you have a design or picture showing the gearing of a motor from prop to the motor shaft? this will be helpful. when i mount my tower i will have a go at fixing the blades directly on the shaft, see how it goes and record the voltage. then i will have to rework the gearing part again. thank you for the info. asvin.b |
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| Dodgeman Newbie Joined: 19/07/2008 Location: United StatesPosts: 33 |
Asvin, Thank you, I just like to understand what I am doing, and I do like to help people any way I can. The only suggestion for gearing that I have is a design I drew up some time ago for a fan blade I had gotten for free, which I had intended to make into a large wind generator in the future 
It is just a quick paint shop sketch of how I had planned to make it, I was planning on having the prop attached to a drive shaft, which will turn a pulley, which will, in turn , spin the smaller pulley on the generator. in the diagram I was thinking of GM alternator conversions but any dc motor should work. I have started smaller and began my actual experiments with dc motors and direct drive instead of rewinding alternators yet. I hope that helps, I am off to bed now, its 11:38 pm here and I work at 5 am, I will check back tomorrow. Nice chatting with you, and I hope we can learn from each other. Dodgeman |
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| asvin bahadur Newbie Joined: 29/07/2008 Location: MauritiusPosts: 21 |
thanks for the design. very interesting. will keep you update. asvin.b |
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piercy007 Newbie Joined: 27/06/2008 Location: United KingdomPosts: 28 |
Evening Please excuse the thread hijack but I am in a similar situation whilst looking at suitable motors. Already tried an old golf trolley (barely made 1/2 volt) and a stepper motor that I can not get anything out of!! Found a motor on ebay that looks ok: 180 watt 2800 rpm 240 volt Using your simple formula and based on low RPM I am estimating the following: 2800 180 700 45 175 11.25 43.75 2.8125 so to get 12v I would need 200rpm (or a voltage double) 
Nb - It's a single phase motor- is that ok? My middle name is luck mind you my first is bad! |
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| Dodgeman Newbie Joined: 19/07/2008 Location: United StatesPosts: 33 |
can you post a link to the motor? or similar? |
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| piercy007 Newbie Joined: 27/06/2008 Location: United KingdomPosts: 28 |
Heres one of them Crompton and another one cheers My middle name is luck mind you my first is bad! |
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| adric22 Regular Member  Joined: 06/08/2008 Location: United StatesPosts: 47 |
I don't believe these are permanent magnet motors.. They are most likely series-wound. They would require major modifications to be generators. |
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| piercy007 Newbie Joined: 27/06/2008 Location: United KingdomPosts: 28 |
Thanks Adric Finding it really hard to even come across a decent motor let alone actually pick one up. Back to ebay then even though latest search for a PMM came up with zero!  My middle name is luck mind you my first is bad! |
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| Dodgeman Newbie Joined: 19/07/2008 Location: United StatesPosts: 33 |
Both of those motors are AC motors, (alternating current) noted both by the "AC" designation and the hz (or hertz) rating in the descriptions and on the data plates. unless you are milling the rotor, adding magnets and possibly rewinding the stator, then chances are that, You are looking for a direct current or DC motor, you must also be careful to find a permanent magnet motor, as some dc motors are shunt wound, which means that they have a field coil which requires power to energize, before the mill will make voltage. I dunno about ebay UK, but here in the USA, some search terms I use are, -dc motor- -pmdc-, -dc pm-, -Magnet motor-, -direct current motor- and so on. Then, I will search by motor manufactures like Dayton or Leeson, so I will search -dayton dc- or -leeson dc- The trick I have found when searching on ebay is to search every possible term that a seller could mistakenly list an item as, use as many names for the same thing as you can think up. I did a quick search for -dc motor- on the UK ebay and only got some 96 items, the same search on USA ebay turned up 448 items, I dont know if shipping matters or how much it would cost, but maybe search our ebay? heres a few item numbers to try Item number: 280253003470 http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=2802 53003470&ssPageName=STRK:MEWA:IT&ih=018 Item number: 200244164231 Item number: 200245029110 you can copy and paste the item number into the search bar on ebay. these are the types of motors I look for, and have actually purchased 1 of so far. I hope that helps. |
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| asvin bahadur Newbie Joined: 29/07/2008 Location: MauritiusPosts: 21 |
hi dogdeman Hello I’m back. Hope you have been well. On my side i have made some progress since my last post. I manage to build my tower on my roof. Please see pictures. The pole is 10 cm inside diameter and is very heavy (6 feet high). It has two 40mm poles as supports with a base in concrete 4 by 3 feet. The concrete base was sealed on polystyrene to absorb the vibration and reduce the noise level. After a lot of trials and errors, I have been able to design and make a head base for the wind turbine. Base on your advices I have included a gearing system. The blades are made in PVC and are around 3 feet in length. Yesterday I connected the blades on the tower and it work just fine. It turned like mad. I even got scared at one point. It was noiseless and there was no vibration. I further added metal wires to support the tower as an extra safety measure. I left it over night. I guess this was still the easiest part although it took me a while to gather the entire spare parts and getting them adjusted/ modified. The biggest challenge was to find a way to connect the 12 DC motor to the head and getting it to work. I spend all my Sunday trying to do that. The engine was fixed on top of the front part. It became very heavy but nevertheless manages to place it on the tower. The problem is that because of the gearings it became slightly hard to turn by hand and therefore did not turn at all even in strong wind. I made lots of adjustments to make the gearing smooth. When I turned the blades by hand, it does rotate to around 10 times but then eventually stopped dead. I need to find a solution to my problem and I am desperate now. I still need to take a picture of the turbine with the DC motor attached to it. Please advice. 
asvin.b |
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| asvin bahadur Newbie Joined: 29/07/2008 Location: MauritiusPosts: 21 |
just posting some more pictures of my wind turbine with the motor. will try to get a close up later on. cheers 
asvin.b |
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| Dodgeman Newbie Joined: 19/07/2008 Location: United StatesPosts: 33 |
Hello again, Good to hear from you, and nice to see that you have progressed, Your whole machine looks very stong and capable to me. I love your tower too, I know my tower needs work to be as sturdy looking as yours 
(I have recently regressed rather than progressed, but I will post about that in my other thread 
I think your gear design looks great also, I would like to know, What that gear assembley is from ? From the pictures, I cannot see why it would not spin in the wind. I do believe that there may also a "magic gear ratio" that must be found in order to compromise between startup capabilities and RPM at a given windspeed. Unfortunatly, I am afraid that, that "magic ratio" will probably have to be determined by repeated trial and error. For mine, I was looking at starting with a 2.5:1- {1 drive shaft RPM to 2.5 motor shaft RPM} to begin with, this should put my motor RPM up in the 500-600's in good wind (I really need an anemometer also) What gear ratio do you figure you have there? I am guessing here,, but I counted what I could see in the top picture and guesstamated about 60-70 +/- teeth on the large drive gear and about 15-20 +/- on the driven gear (<motor gear) I am assuming this ratio, but, 65/17 gears would give you a ratio of 3.82:1. That would speed your motor up quite a bit, but as the ratio increases from 1:1, it gets proportionally harder to turn, Your description would make sense as to why its very hard to start, especially if your motor has strong "magnetic cogging" also. If I understand correctly, you said that: "it spins like mad without the motor" ??, with no load on the Prop? or, do you have the motor loaded as well? With a DC magnet motor, it will become harder to spin, as it encounters electrical resistance from the load. I wonder, if your wires may have been shorting to ground? causing difficult startup/turning of the motor? I also wonder, if 3 ft PVC blades are long enough and/or wide enough to to catch enough wind to get it moving with the motor/gear resistance. Also, is that drive shaft mounting apparatus a ball bearing carrier? or is it a sleeve/ bushing type? It's tough to tell from the pic. (as I am sure you know>)a bushing would create some added rotational resistance as opposed to a ball bearing setup. I sincerely hope that I have not advised you wrongly by suggesting the addition of gearing to your mill, I know how much work it all is to put together, I do plan to gear my current motor as well. From my non-geared experiments, I have been unable to produce the continious voltages I am looking for, with a direct driven 90V/DC motor generator. Please keep us posted in your progress and keep at it, you have only discovered 1 way that it wont work, 999 more to go and you will have it
DM. |
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| asvin bahadur Newbie Joined: 29/07/2008 Location: MauritiusPosts: 21 |
hi, good to hear from you and thanks for the reply. you mentioned some very interesting points in your reply and which sound very reasonable. i will try to answer some of your questions. I would like to know, What that gear assembley is from ? it came from an old textile machinery. well the gear on the dc motor is around 3.5 to 4 cm in diameter and the one in the picture above is around 15 to 16 cm in diameter. If I understand correctly, you said that: "it spins like mad without the motor" ??, with no load on the Prop? or, do you have the motor loaded as well? it spin very well with no load. also i don't think there is any electrical resistance because i did remove the carbon brushes from the engine as i thought it was causing some kind of brake. Also, is that drive shaft mounting apparatus a ball bearing carrier? or is it a sleeve/ bushing type? It's tough to tell from the pic. It has not ball bearing. it a part that i found and which was used for something similar in a machinery part. asvin.b |
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