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Forum Index : Windmills : Harvesting all or most of the power from
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| Wes Lemarr Newbie  Joined: 07/09/2008 Location: United StatesPosts: 35 |
Their seems to be a problem that’s common to all windmill generators & it is that the generator is capable of producing much more power (volts & amperage) in higher wind speeds (30 MPH to 60 MPH) than the batteries can handle. My mill produces: up to 80volts at 35 amps at 600 RPM, what is needed is some method of “funneling” all of this power in to the batteries. It seems to me that about 2/3 of the mill power is wasted? Have any of you guys found a way to harvest all or most of the power from your mill? Wes LeMarr |
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| okwindpower Newbie Joined: 21/06/2009 Location: United StatesPosts: 4 |
Wes, it sounds to me like you have way too small a battery bank for your wind generator. If you are using automotive wet cell batteries, typically you will damage them by charging them at much more than 20 amperes. If you go ahead and spend the money on a large enoughh battery to handle the power that you can produce you will find that the battery can easily handle the higher charging load that the wind genny is supplying. As for the 80 volts you are stating, what is your system voltage? I think that I am familiar with you system but not certain. If you are chargine a 12 volt battery at 80 volts, you and the battery are not going to be very happy campers for too long. Mike |
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MacGyver Guru  Joined: 12/05/2009 Location: United StatesPosts: 1329 |
I don't store my wind power using electricity, so this is just a suggestion: Why not adjust your voltage regulator to shift any wind-generated power above 15 volts to a circuit that heats water? That way, you could capture the overage and do it in a manner that will power a device that is a current-hog anyway and you won't have to worry about cooking your batteries. Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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GWatPE Senior Member  Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi Wes, these numbers are presumably unloaded volts at 600rpm and the max current seen from the alternator. If so, then this is not the real picture. what measured power levels do you have? The diversion/dump load is enabled when the mill produces more power than the battery and normal loading can absorb. The percentage of the time that these extreme power levels occur will determine if there is value in adding it to the normal loading. Gordon. become more energy aware |
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Smart Drives Senior Member Joined: 06/07/2009 Location: AustraliaPosts: 115 |
I agree with the battery bank being too small, in our nightmare winds last night and ths morning i noticed something very interesting. Last week i had 6 300amp/hr batteries connected in series: in medium winds , my voltage from the batteries went up quickly and the dump load was activated at approx 35km / hr or 10m/s. 2 Days ago i set up 2 12v 300amp/hr banks in parallel (not good for long life of batteries) so 600amp/hr. My Dump load didn't activate until the winds hit at least 50 - 60km/h. And then instead of staying on for minutes at a time it barely flickered on and off. I was very impressed. All smart drive parts sold Custom built turbine parts on Multicam flatbed CNC Router |
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| GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi smartdrives, the 6x300Ah batteries in series. Is this a 72V system, or a 12V system? Were the batteries in both tests of the same age type, and cyclic pattern use, and at the same initial charge? You need to comparte apples with apples. Gordon. become more energy aware |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5119 |
Hi Wes The guys are going to need more information. What size battery have you been testing with, its possible the windmill is over powered for the battery you have. Also the open circuit voltage of 80volts or a short circuit amp reading of 35 amps isn't telling them anything, what they will want to know is how many amps could the windmill feed into a 12 or 24volt battery, that will give us its true power capability. If the battery is charging too quickly to do a proper test, then you'll need a bigger battery or some way to load the battery down as its been charged by the windmill. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| Smart Drives Senior Member Joined: 06/07/2009 Location: AustraliaPosts: 115 |
It was a 12v system , they are all the same type of 2v battery. One bank (6 x 2v) may have been .1v higher than the other bank. Cameron. All smart drive parts sold Custom built turbine parts on Multicam flatbed CNC Router |
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| Wes Lemarr Newbie Joined: 07/09/2008 Location: United StatesPosts: 35 |
OK guys, I think the message is that I need a BIGER BATTERY BANK & I agree & thank you all for your help! Now the next question is how big dues the battery bank need to be? I have two lead acid 12 volt 80 AH batteries, if I connect them in parallel (80 X2 = 160 AH @12 volts) will that due as a minimum or do I need more? Is it possible to state the size of a minimum battery bank in terms of watts, voltage or amps or no matter how many batteries it takes to reach the desirable size? I apologies for asking so many basic (Dum) questions but as many of you probably already know we are about to introduce our small wind generator & I need to offer some reconditions with regard to the size of the battery bank as well as the controller to use to the people that buy the generator. We would love build & include a simple controller as part of the windmill kit, but have not found a suitable design so far, any suggestions? Thanks Again Wes LeMarr |
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oztules Guru Joined: 26/07/2007 Location: AustraliaPosts: 1686 |
It is near impossible to advise a minimum battery size as it is completely dependant on the application in mind. If you have a decent dump load attached to it, no matter how small the battery bank is, it won't be overcharged.... so how long is a piece of string anyhow?? For a proper figure, you must look at the KWH storage you need to achieve your objective (ie how much power is envisaged to be used for how long before you can expect the wind to appear again and charge the bank back up.) This will differ from user to user and wind site to wind site..... so there is no one size fits all. As a starting point, golf cart batteries are very tough (Trojan T-105 etc), about 200ah and would be a good starting size for most projects for a little mill. It will give a reasonable storage size for little projects, and they are plenty tough.... wet cells give the novice more room for mucking up I reckon. A wild guess would look like this: If we think/hope we will get an average of 10A@12v into the batteries throughout a day, it would equate to 120w/hour...x 24h would look like around 3kwh. Anecdotal evidence would suggest that this is a bit on the highly optimistic side, and that a small mill on a small tower in an average wind regime would probably struggle to do 1/3rd this power... so maybe 1kwh. 2xT105's will get you about 225x12v=2.7 Kwh of storage. To get decent life from the battery you don't want to discharge too much, so this will probably be a reasonable match... but a blanket recommendation is rubbery at best. The important part is to prevent the mill boiling the batteries mercilessly.... and hope that their inverter has a low voltage cut out to prevent over discharging. The dump controller will stop the over charging.... so problem solved. Their are nice circuits presented here and elsewhere for basic dump controllers, and I have designed/built my fair share of gadgets too..... However, as a manufacturer, I would seriously consider talking to this man G. Hurd about your project. He is in the USA, has a huge amount of experience in selling these things to novices all around the world, and seems to have very good feedback from all his customers...... and is held in high esteem by them. This is pretty rare in the RE world...... The one problem might be trying to make them look expensive 
One problem with the Chinese mill is their controllers. They seek to be too smart by half, and instead of being all things to all people,.... simply give out in the first month. You are more likely to meet with success if you use the dump load as a dump load, and not a smart mill controller. You seem to be able to count one one thing.... silicon switching exposed directly to a wind mill... will burn up sometime..... If you are going to recommend anything you will need to find out some basic things about your mill. How big is it, and how powerful is it. How many amps@14-15v is it capable of, when does it furl etc etc..... in other words, what is it's watt rating at what windspeed. From that you can place it in the wind regime, and get a vague idea of it's kwh expectations... a starting place at least. .........oztules Village idiot...or... just another hack out of his depth |
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| Wes Lemarr Newbie Joined: 07/09/2008 Location: United StatesPosts: 35 |
.........oztules You comments were very helpful & I am beginning to get the picture. I ordered a couple of G.Hurd’s dump controller kits to try. Thanks! Wes LeMarr |
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| Wes Lemarr Newbie Joined: 07/09/2008 Location: United StatesPosts: 35 |
.........oztules I would like to contact you by email if I may; I am guessing you probably have pretty good wind down there in Flinders Island which might make it an ideal place to test my small generator? If you have any interest please contact me directly at wes@oemparts-express.com. Regards Wes LeMarr |
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