A couple of days ago when temperatures here reached 105 in the shade, my wind turbine’s permanent magnet generator was damaged. The magnets were subjected to temperatures (180 degrees or more) such that voltage produced has dropped from thirteen or more to nine or so at the same turbine speed. I have a deep-cycle battery array of four six volt batteries hooked (of course) in series-parallel. I’ll build another generator (I was designing another turbine, anyway) but meanwhile I’m wondering if there is an electrical control device - relay and sensor - that I could use to charge one battery at a time, switching as each battery reaches full charge.

Obviously and since I can now only generate nine bolts, I'd like to charge one battery at a time. Is that possible? THANKS!

 

nine bolts

That would probaly be pretty simple . I'll drop in tomorrow If I have time to draw up a schematic if someone else doesn't beat me to it

 

With the 9 volts, a single six volt battery can be recharged at a time, if, those 9 volts are real and not a high impedance reading.

I would suggest check for charging current into a single 6V battery to confirm. And depending on the type of generator, trouble shoot for other failure causes.

If the 9 volts produce no charging current, the generator needs repair likely not related to magnetism loss.

 

"Shagas," I look forward to your comments. "Externet," the generator is a permanent magnet type I built myself. It charged four 12 volt (hey, I spelled that right!) batteries nicely for more than two years. The voltage reading is with a multimeter at the turbine generator itself and at the rectifier. What I'll need until I have the new turbine and generator built is a way to charge one battery at a time. The array runs my aquaponic garden's pumps, aerator, and air conditioner. Thanks for you help.

 

The voltage reading is with a multimeter at the turbine generator itself and at the rectifier.

I'd check that rectifier. If all you need is new silicon, that'd be an easy test and easy fix.

 

"Shagas," I look forward to your comments. "Externet," the generator is a permanent magnet type I built myself. It charged four 12 volt (hey, I spelled that right!) batteries nicely for more than two years. The voltage reading is with a multimeter at the turbine generator itself and at the rectifier. What I'll need until I have the new turbine and generator built is a way to charge one battery at a time. The array runs my aquaponic garden's pumps, aerator, and air conditioner. Thanks for you help.

If it just a temporary solution, you could use a DC-DC converter to raise the voltage up to where you need it. It will just take longer to charge the batteries since you have less current available.

 

"LDC3," I've thought of that, and am trying to find one I like on the Internet (local stores don't seem to know what I'm talking about). I've also asked the manufacturer of my charge controller about compatibility with the step-up converter. I'll measure the current once I've installed the converter (assuming I find one), but meanwhile is there a way to compute how much amperage loss there will be (I guess I need to think about that a bit, huh?). 'Wayneh," I think that since the multimeter voltage reading at both the rectifier and the turbine are the same, the isn't likely a defect in the rectifier - or am I missing something where that's concerned? Meanwhile, thanks to everyone for their prompt responses - much appreciated.

 

'Wayneh," I think that since the multimeter voltage reading at both the rectifier and the turbine are the same, the isn't likely a defect in the rectifier - or am I missing something where that's concerned?

I wasn't sure what you meant by that, whether you had actually gone back all the way to the turbine.

The curie point for your (neodymium?) magnets is over 300°C, which tells me that there were probably other problems long before you reached that temperature. My guess is melted insulation in the coil windings, shorting out many loops.

 

The information I have is that neodymium magnets begin to lose magnetism at 176 degrees. The manufacturer confirms that. I've checked all the circuits, all the components, such that all that's left to explain the drop in voltage at the same turbine speed is loss of flux between the alternator magnets. I frankly don't want to spend the money for a flux meter, and my calculator Fourier analysis (I don't have a fluxmeter, unfortunately) of the mathematics having to do with lessened voltage, fits closely that of records having to do with the turbine's design and output to date. It's the magnets. As I said, I'm going to build a new, (contra-rotating, this time) turbine and generator, but right now, the new turbine design still in the process (I'm not an engineer, so that's taking me a good deal longer than it might require otherwise), I need to run my aquaponics garden electrical system (or my catfish will die). The batteries are my back-up for the electrical grid power, and have to be charged should the regular electrical power go down. Normally, the turbine has powered everything - the batteries remaining charged and on stand-by - that due the fact that the wind here is at twenty-five miles an hour almost every day. Thanks, however, for your help (and comments) - it's much appreciated.

P.S. Wouldn't melting of the stator wire coverings require temperature much higher than that required to weaken the magnets (176 degrees)? I think so. This is 15 AWG generator- electric motor wire, by the way. Good thought, though, I'll check with the electric motor factory where I bought the wire.

 

The information I have is that neodymium magnets begin to lose magnetism at 176 degrees.

You're right. I mistakenly only looked at the Curie point, which is much higher at 310°C. I didn't realize there is irreversible loss well before that point. In fact I was surprised to learn that even 80°C can cause irreversible damage to a N42.

 

You could eat the catfish and just get new ones when your new turbine is finished.

OK, bad joke. Yes, it is possible to charge each of your 6V batteries one at a time. Question is, is it feasable? You'll need a 6V charge controller to connect to your 9V outputs, and then a sequencer to switch the individual batteries. I don't know of a commercially available sequencer. One can be made easily, but maybe not in time to save your farm. Best thing is to buy an inexpensive 12V charger and connect to your system to run it until your new turbine is ready.

 

P.S. Wouldn't melting of the stator wire coverings require temperature much higher than that required to weaken the magnets (176 degrees)? I think so. This is 15 AWG generator- electric motor wire, by the way. Good thought, though, I'll check with the electric motor factory where I bought the wire.

A lot of plastics will soften around 100°C. At 120°C, the insulation could flow enough so a short is possible.
A possible way to check your magnets is to hold a small iron nail near them and see how strong the attraction is. Compare the attraction to a known good magnet and you should be able to tell. You're losing about 50% of your voltage so I would think that it corresponds to 50% of the magnetic field.

 

You might check the DC resistance of the windings, if you know what it used to be OR the length and gauge of the wiring.

 

You might check the DC resistance of the windings, if you know what it used to be OR the length and gauge of the wiring.

Hey, great idea! It happens I DO know what resistance was when I built the stator. I also know the length and gauge of the stator coils wire, so I'll do the numbers, get up on the roof tomorrow and check. I'll also check magnet strength as "LDC3" suggests. I have some magnets of the same N number from an earlier project.

Meanwhile, I'm hunting a suit able step-up converter. After having lost three batches of catfish to air pollution (result: I built a greenhouse around the fish tank), to Texas heat (I dug a subterranean heat sink and installed a small air conditioner in the greenhouse), and finally when run-off during a torrential rain flooded my fish tank sump with insecticide off the lawn (I closed the sump and grow beds in with a landscapers plastic barrier) , I'm determined to save the fish I have left. I finally succeeded in growing a very nice crop of tomatoes in the aquaponic garden's grow beds, so I'm not going to surrender anything more.

Thanks, gentlemen, for your generous assistance. Much appreciated.

 

After having lost three batches of catfish to air pollution ...

Really? I'm curious what in the air could possibly cause a problem?

Have you ever looked at using spent totes as fish tanks? They're ~1,000L, have an opening in the top and a valve on the bottom. They're widely used for shipping less-than-truck loads of, for instance, food grade liquids. I had a work colleague that was keen to start an aquaculture business using these, since they're nearly free once they've been used.

 

Really? I'm curious what in the air could possibly cause a problem?

Have you ever looked at using spent totes as fish tanks? They're ~1,000L, have an opening in the top and a valve on the bottom. They're widely used for shipping less-than-truck loads of, for instance, food grade liquids. I had a work colleague that was keen to start an aquaculture business using these, since they're nearly free once they've been used.

Those totes are not so expensive new either ($150).

I am really surprised that catfish are sensitive to air pollution. They seem to thrive in the refinery and petro-chemical producing arm pit of the gulf states.

 

For anyone who might be interested, here is the turbine and aquaponic garden I've been talking about. Thanks again for the assistance.

 

For anyone who might be interested, here is the turbine and aquaponic garden I've been talking about. Thanks again for the assistance.

What do you grow in the vertical tubes?

 

Really? I'm curious what in the air could possibly cause a problem?

Have you ever looked at using spent totes as fish tanks? They're ~1,000L, have an opening in the top and a valve on the bottom. They're widely used for shipping less-than-truck loads of, for instance, food grade liquids. I had a work colleague that was keen to start an aquaculture business using these, since they're nearly free once they've been used.

Oh, yes - and next time I build, I'll use them. But when I started my project, galvanized stock tanks were available nearby. Growing up in Iowa, I'd seen people raise catfish in these tanks for decades without trouble, but when people began telling me about zinc leaching into the water, I'd already spent my money. I lined the tanks with fish pond plastic, and started over. The area has acid rain regularly - that due the locality being surrounded by plastics and chemical manufacturers, oil refineries, and nuclear power plants. Whatever's in the rain - it can be a dozen or more things - it kills fish. Then, too, the land where we live grew cotton and is heavily soaked with the arsenic with which cotton farmers defoliate their plants.

So, I built a greenhouse around my fish tank, and put a roof over my grow beds. Next run-off from a neighbor's insecticide and herbicide-treated lawn got in my aquaponics garden's pump sump and it killed all my fish. I put a landscaper's barrier in the ground around the sump and grow beds, and it has prevented further loss - even in the very rare rainstorms we have here. I may get our first batch of catfish soon - some are over a foot long. Wish me luck?

 

Those totes are not so expensive new either ($150).

I am really surprised that catfish are sensitive to air pollution. They seem to thrive in the refinery and petro-chemical producing arm pit of the gulf states.

Yeah, and what it is in the air I'd really like to know. It will kill some plants immediately - they shrivel up and are dead within one day. When it falls on me as I work, any scratches or abrasions "burn" and sting painfully. I've sent samples to several laboratories, but there seems to be some kind of conspiracy going on - none will reply. When I do my own tests, the local city manager, Texas Commission on Environmental Quality and Federal authorities all "stonewall." Several persons, even counties, have filed suit to stop the pollution, all to no avail (these people have massive amounts of money to spend - money they will recoup from their customers when they raise prices in order to compensate whatever the lawsuits cost). Radiation in the water supply - affected by uranium leach-mining in the area - often goes off the scale. I do, and have been doing for years, my own radiation testing, such that there is absolutely no doubt of the fact. More, birth defects, liver cancer, and several things more normally associated with radiation absorption are rife, but its the state's best kept secret.

We'd leave, but my wife's 95 year old father won't go, she won't either, and I'm stuck. So the fight to survive goes on - the reason I'm trying to produce my own energy, grow my own food, and purify our water (we spent $7,000 after having done the radiation tests, in order to assure the water we drink and bathe in is safe). With Fukushima radiation blowing in every time the jet stream dips this way, who knows how long we'll keep ahead of it all?