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Forum Index : Windmills : 80-100A Charge Controller Options?
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Downwind Guru  Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
Phill is very correct if you are looking for a charge controller with battery maintenance control for use with solar as well. My comment was for windmill only control, as a mill will never fully charge a battery anyway, because they switch to dump early due to the nature of controlling a mill with a resistive load. If a high priced controller is used for only mill control then its a waste of $$$$ IMO, as it will only function as a voltage On/Off switch and not operate like a charge controller should to maintain battery charge maintaince. As phill said if you intend to add solar as well then a good controller is worth the investment, but due to the original question asking about a controller for a windmill only, i see little point in spending big dollars for a rather simple dumb device to monitor voltage and switch a mill to dump. In the past i have built many simple voltage controllers for windmills, and Phill might even still have a few he could sell you, if all you want is a voltage dump controller for a mill only application. Pete. Sometimes it just works |
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| BlueSmoke Newbie  Joined: 02/05/2013 Location: United StatesPosts: 25 |
Couldn't agree more on maintaining the batteries, they are expensive and very worth protecting. I think it's worth distinguishing between wind and solar here. There may be good controllers that can handle both wind and solar but I tend to treat them separately and feed them to a battery bank separately. In the best of worlds, both would address bulk, absorption and float charge (especially for gel or glass mat). The battery bank will buffer both wind and solar input and respond to both wind and solar so hopefully both are tuned to assist in battery maintenance. Another consideration (other than battery maintenance which, I agree, is very important) is protecting the stator windings from overheating. By diverting the load from the wind turbine directly to the dump load, we are essentially shorting out the stator and possibly causing overheating there. This is not a problem if occasional, as in braking, but during high wind conditions could become problematic (IMHO). The 80A Coleman Air that I have can easily be set up to either apply the dump load to the wind turbine input alone or apply the dump load to the wind turbine and the batteries together. I've chosen to dump both the wind turbine and the batteries so I have some buffer to the effect on my stator during high wind conditions. Perhaps I'm protecting my stator when I should be looking more at protecting my batteries ... ... I would suppose it depends on how well cooled your stator is, how big your battery bank is and what your controller settings are as to when to dump. I have no doubt that there is a sweet spot there, but this may differ and need to be tailored to each system. Note: I find this discussion very interesting and look forward to further comments. Great posts, everyone, the diagram really helps and gives me a new way of looking at this issue. Thanks to all. BlueSmoke |
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| Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
That is the general thinking but far from correct, the mill is only shorted via the resistors and its why there is resistors in the system to limit the loading and remove the power and put it into heat elsewhere. Its really no different to having flat batteries that can adsorb mass current in high winds, lets face it there is no difference what source we divert the Watts of energy to, we just need a source capable to handle the energy (watts) produced to control the mill. Direct shorting a mill is much different, as with a direct short you only have the wire resistance between the alternator and the load/short. This means great energy is generated in the coils and dissipated via the coils, not what i would consider a ideal control method. You will always encounter situations where you require control over maximum output of the mill, this is normally 1 or 2 times a year, but you need to be ready and understand what is needed to control the situation. That is not a very realistic view if you fully understand how a windmill power is controlled compared to solar. Yes it can be done for windmills, and one method i helped Phill develop was his variable fluid resistor control, it worked well dumping power on the AC side and would control voltage to 0.1V to the batteries. Another is to use PWM control of the resistor bank, but there is problems there like the EMF noise that is generated, basically you have a huge radio transmitter via the resistor windings, causing allsorts of havoc, like noise on your (and anyone else) radio, bad tv reception, open and closing your neighbours garage door, car remote door locks etc, etc, it all depends on the pwm frequency used. To me almost all mill controllers lack one basic function, being not monitoring RPM. I think mill control is a 2 part system. 1) first we need voltage control to protect the batteries from over charge. 2) Monitor rpm and switch to dump at a preset rpm speed, its far better to dump the power (hit the brakes) at a controlled setting, then it is to let the mill over speed to awesome power and then try to control it. You can calculate roughly what rpm will produce max rated power, and its easy to exceed the power rating by 50% in high winds and high rpm. Why wait to get to 150% then try to control a mill (voltage only), its a runaway mill by that stage and is likely to burn out anyway. My mill uses my own designed controller that monitors battery voltage and switches to dump at 28.5v for a 24v system. It also monitors rpm and switches to dump at 400rpm, it remains locked in dump for 10 seconds then releases the brakes and reads the rpm again, if the rpm is greater than 400 rpm then it his the brakes again, repeating.............. You ask why the 10s period of braking, its due to the rpm is extracted from the 3 phase AC frequency, and during braking the AC voltage falls below a readable level to monitor frequency, its like driving the car and braking for 10s then checking the speedo and braking again, all in a few milliseconds of checking the speed. If i can do it with rpm then why are not others doing the basics in mill controllers? The main question is why wait till your mill is a runaway then try to control it, where hitting the brakes early and placing the mill in stall and riding out the storm, to survive to fly another day is far better than 5 minutes of huge power you cant deal with (bragging rights), followed by picking the pieces of mill up from a scatted radius. Pete. Sometimes it just works |
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wallablack Senior Member  Joined: 10/08/2011 Location: AustraliaPosts: 164 |
Phil & Pete...........Thank you. If you haven't convinced mill owners to dump via mill you never will. I am convinced this is for sure the only way to go. Thanks Phil for the diagram, to see what is being discussed certainly sheds some light on the subject. Without talking really cheap crap what would you consider to be a good type of battery. After a lot of looking around I totally agree 100% with this. I just picked mine up for $265...To me, that is cheap all things considered. That is a great read, very very interesting... After reading the link Phill posted on battery guff, and what you mention Pete I will be definitely be adding solar to the mix. Just enough would be the key here I believe. That is a very cool idea...very cool. I think it is a great idea and I think "the hobbyist" isn't doing it due to lack of knowledge I guess. This has been a VERY informative piece of reading and one that has changed my whole perspective on everything. Worth a read by everyone I think. Foolproof systems do not take into account the ingenuity of fools. |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
That is a GREAT source of information Fillm. Interesting that the author does not believe that pulse type battery desulphators are of any value. When I was a Telecom trainee technician (almost fifty years ago), we were taught then that any significant ac ripple on a battery charger would cause plate erosion, and the purest most well filtered dc possible was recommended for charging. We were even shown pictures of ragged battery plates taken from failed batteries to prove this was so. Times change, and so does generally accepted wisdom. Possibly this article is quite old (?) and the author's idea of pulse charging is quite different to the very fast inductive flyback pulsing that modern electronics now makes possible. Cheers, Tony. |
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fillm Guru Joined: 10/02/2007 Location: AustraliaPosts: 730 |
Hi Tony , Whether the article is quite old really makes no difference, the best info usually is ,as back then they tried to make things last. Deep Cycle Lead Acid battery's are still the same in the way they are charged and maintained as they were 50 years ago , may-be construction methods have altered slightly . Pulse charging or De-Sulphators are IMO no different than" Snake Oil " basicly Bull S#!t , the only conclusive evidence that they work comes from the maker/seller, and to bring old heavily sulphated batteries back to a semi usable state is more due to the leaving it on trickle charge for 3 months with the de-sulphator connected . More than likely it was just pooly maintained and charged . PhillM ...Oz Wind Engineering..Wind Turbine Kits 500W - 5000W ~ F&P Dual Kits ~ GOE222Blades- Voltage Control Parts ------- Tower kits |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
That is not strictly true, I still have an open mind on the whole subject. Several knowledgeable posters here on this Forum say they have used desulphators with considerable success in restoring amp hour capacity. But obviously a totally failed cell is not going to respond to desulpation, and some of the low cost commercial desulphators appear to produce only flea power pulses. Despite the myths and internet B.S. it has definitely worked for some people, so who knows ? Cheers, Tony. |
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| fillm Guru Joined: 10/02/2007 Location: AustraliaPosts: 730 |
Well I would ask to be shown controlled identicial tests with one on a desulphator and the other trickle charged or other methods . In reality to have a battery on trickle with a desulphator for 3 months with the cost of power these days + the cost of the desulphator would probably almost pay for a new battery and be better of in the long run . And who in their right mind is going to sit around for 3 months waiting for the battery to get a few extra A/hrs And when you really look into it to , to do a set decent size battery's with desulphators recommended for that capacity is a small fortune. I personally would want conclusive evidence before parting with $. PhillM ...Oz Wind Engineering..Wind Turbine Kits 500W - 5000W ~ F&P Dual Kits ~ GOE222Blades- Voltage Control Parts ------- Tower kits |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
You cannot do identical back to back tests, because there is no way of knowing for sure what, or how bad any battery problem really is. And it does not take three months to remove mild sulphation. Cheers, Tony. |
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| fillm Guru Joined: 10/02/2007 Location: AustraliaPosts: 730 |
Tony , Do you actually own a desulphator and have personally tested the claims, or are you just going on what is on the internet? I do , and have not seen any miraculous results other than wasting time and power. PhillM ...Oz Wind Engineering..Wind Turbine Kits 500W - 5000W ~ F&P Dual Kits ~ GOE222Blades- Voltage Control Parts ------- Tower kits |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Yes I own a homemade desulphator, a fairly powerful one. It outputs genuine eight amp very fast rise time pulses. I use it for keeping a standby gen set battery fully charged, it turns on and off very briefly (as required) over a fairly long cycle time to counter battery self discharge. It will be interesting to see if this works better than a temperatrure compensated float charger. I have not yet had a battery sulphation problem to test it on. If this PREVENTS sulphation in this application, I will be more than happy with it. To be fair, the whole thing has only been in operation a few weeks, and the verdict will be a long time coming. Cheers, Tony. |
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| Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
I too are on the fence with the desulphator debate, i also have a "Recommended"bought brand name desulphator on my battery bank, and as far as i can tell it has done diddlly squat to suggest it has been worth the cost of the desulphator unit, then as far as i can tell its also done no harm, so who knows if over the last 2 or more years if it has helped or done nothing more than consume power for the red/green led on a panel. From what i have been told or even understand works well is the Jaycar Kit Mk2 desulphator, and that was around $100.00 just the kit and then you had to build it yourself. (gives a reasonable idea to the cost of actual parts big enough to do the job) If you look at inductor sizes and other details they addressed and used in the design then it might well work, where most have a tiny inductor delivering far smaller bursts of energy. You might think of it as using a electric toothbrush or a jackhammer to break the sulphation. and i feel my desulphator is of the toothbrush range and good for diddly squat! Pete. Sometimes it just works |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
These are not that difficult to build, and the flyback inductor is the heart of it. I used a one millihenry ten amp torroidal choke that I already had, but if I was going to build more of these I would seriously look at loudspeaker crossover inductors. Air cored coils are rather large, but they have the advantage of being totally free from magnetic saturation problems. They can be pulsed to several amps without difficulty and should do the job well. Jaycar supply a fairly good range of these, or you could very easily wind your own. You can also get away with using a small plug pack as a power source, provided there is a monster electrolytic to store energy and pull really high current from in short bursts. The commercial desulphators and most of the kits only use tiny inductors which can only store very small amounts of pulse energy. A typical plug pack might supply around six watts, and just about all of that could be pulsed into a battery giving about a third to a half amp of average charging current. Not huge, but certainly enough to be very useful. Cheers, Tony. |
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| fillm Guru Joined: 10/02/2007 Location: AustraliaPosts: 730 |
Tony , I would urge you to start up a dedicated thread on "Battery Desulphators" with a " How To " ,and actual circuit diagrams on building one with a basic principal of teaching rather than just saying "they are easy to build" . With that in mind then the word "Snake Oil" might be dispelled from the word "Battery Desulphator" and those that build them can then test and report their results . From what I understand the frequency and pulse strength needs to be matched to the battery size and type and with most of the ones on the market claiming to be universal. PhillM ...Oz Wind Engineering..Wind Turbine Kits 500W - 5000W ~ F&P Dual Kits ~ GOE222Blades- Voltage Control Parts ------- Tower kits |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Well it seems there are several competing theories about how these desulphators actually do the job they are supposed to do, and I am definitely no chemist or physicist, just a rather curious engineer. But to me, the most convincing explanation I have read so far, seems to be that sulphate crystals end up being pretty tough and efficient insulators, and do not respond very well to direct current flow, if at all. However, a very fast rising pulse contains a packet of very high frequency harmonic energy, and can force a high displacement current through the dialectric of these stubborn insulating crystals, and a very small capacitance can couple a surprising amount of high frequency energy. So it's probably not the pulse repetition frequency that matters so much as having as fast as possible rise time, and a decently high peak pulse current. At least that is how I visualise it. But I cannot say so for sure. And I suspect (without any evidence) that hitting it really hard with fewer high current rising edges may be more effective at breaking down these sulphate crystals than pecking away at it with piddling low energy pulses repeated at a much faster rate. My Photobucket account no longer works for some reason, and Glenn frowns on images anyway because of the cost of bandwidth, so I can see no easy way to post experimental circuits, but would be quite happy to do so. Cheers, Tony. |
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| fillm Guru Joined: 10/02/2007 Location: AustraliaPosts: 730 |
I doubt that very much , you just need to upload the correct type images using the image upload function on the tool bar . I would think Glenn would welcome a good thread on "How to build a Battery Desulphator" PhillM ...Oz Wind Engineering..Wind Turbine Kits 500W - 5000W ~ F&P Dual Kits ~ GOE222Blades- Voltage Control Parts ------- Tower kits |
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| MOBI Guru Joined: 02/12/2012 Location: AustraliaPosts: 819 |
Pure water is a pretty good insulator to electric current but at a suitably high voltage the water becomes a conductor. Perhaps the sulphate behaves in a similar way. The problem with hitting the battery with the appropriate voltage is that it would blow the guts out of the battery if it was continuous. Hence the use of short, low transition high voltage pulses with a long enough "off time" to keep the current to a manageable level. Just a theory, however electricity does some out of the ordinary things at high enough voltages and/or frequencies. David M. |
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Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498 |
Pure water is a good insulator but as soon as it makes contact with the air and absorbs carbon dioxide it is a conductor. There are only 10 types of people in the world: those who understand binary, and those who don't. |
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| MOBI Guru Joined: 02/12/2012 Location: AustraliaPosts: 819 |
And?? I was talking about pure water not carbonic acid. David M. |
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| Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498 |
But you can not have pure water if it is in contact with air. There are only 10 types of people in the world: those who understand binary, and those who don't. |
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