re: Any of you knuckle draggers ever built your own generator?

A co worker has a windmill that he made at his dads barn/camp. He uses a windmill (blades purchased online) an alternator from a Chevrolet truck, battery bank, and an inverter. He runs all the lights in the barn and a couple fans.

Lots of info on the web of DIY windmills.

You're over complicating it. A bigger drive wheel is all that's needed

Just run pulley to pulley and use the KISS method. I honestly don't know enough about electronics, but I'd assume there is a minimum rotational speed for an alternator to work. Some cars idle as low as 500rpm, so you'd need twice the size big pulley to run at 250rpm, 8x running at 62.5 rpm. You'd need the stream to be running at 4.36mph to do that (based off of my phone calculations with a 2" alternator pulley)

The only problem I can forsee with those is the alternator's pulley size. Smaller = better on that end. Bigger = better on the other end

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If the water wheel is turning at 100 rpm

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If it is turning at 100RPM you better have more than a cable spool with a pipe in the center, that will not last more than a few hours at roughly 2 rev per second, the issue is as things speed up and more draw is applied the alternator becomes much harder to spin. It is going to take roughly 1 hp/kw allowing for friction loss and that is quite a bit of resistance. At some point as resistance increases water just starts to spill over the wheel.

My actual expectation would be roughly 7-10 amps regardless of alternator size as this really has a negligable effect on resistance, if using it to charge batteries for limited occasional use it will be ok, constant power is going to be a dissapointment.

I built one on the outflow of a spring fed pond for shits and giggles and these were my findings, take it for what it is worth.

I think a true water wheel gets much of it's power more from the weight of the water, rather than just the force created by the flow of the water against the vanes. A turbine works on flow but it takes a significant amount of flow to generate enough hp to power a generator of any size. But a water wheel uses a change in elevation, coupled with the weight of the water in the buckets and the pressure of the flow to create the energy needed. The result is a low speed, high torque main gear or pulley that will turn a small gear at high speed to power the generator. If you don't have a change in elevation available to incorporate into the design, it's hard to do. You want the wheel to be as light as possible so you don't use too much hp just to turn the weight of the wheel. Then maximize the volume of the buckets, and the diameter of the wheel to increase the force generated by the weight of the water. It shouldn't be built like a paddle wheel, simply with vanes perpendicular to the axle unless you have a really high rate of flow. The old time water wheels I've seen were built so that the vanes formed long rectangular buckets.

In my opinion your best bet is to utilize a battery bank and then an inverter.

The water wheel is probably going to be the most efficient. The bucket conveyor is essentially a flattened out water wheel. But the round configuration of the water wheel is more efficient because you also get a fly wheel effect. A conveyor design would have to have rollers on each end the size of water wheels to be as mechanically efficient as the ww, if you get my drift. I don't think the conveyor configuration, although more compact, gives you the same mechanical advantage. Remember, you're wanting a large diameter gear or pulley driving a small diameter gear or pulley to boost the rpms at your generator. Where do you put the large gear on a conveyor?

Your turbine idea will work if you have a very large volume of water, moving at high velocity through a choke point. Otherwise you will lose too much of the potential energy. The blades of boat props are too far apart. Even a four blade prop. The water will mostly flow around the blades rather than being forced against the blades. Turbine blades have way more surface area and tighter bypass areas compared to a boat prop.

The old timers were no dummies. They were awesome engineers when it came to making do with the resources they had available, and to my knowledge, almost always used the water wheel as opposed to other water driven devices.

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Hell 10 amps is usable.

Very cool that you actually did it.

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It certianly was not cost or time effective.

My original goal was to produce enough power to run a fountain/aerator but I fell woefully short.

To the OP, I am going to recomend you find something with a bearing, I used a trailer axel cut down to size, to reduce friction loss and build your wheel as large a diameter as possible. You are correct it is the weight of the water that provides the majority of the drive power and the larger the wheel/fall the more power you can make. You will need to sort out bucket placement as more/closer is better but too close and they will not fill correctly, this is flow dependant as well.

Edit to add: I considered the below and likely would have benefited from a reverse wheel with a tailrace as pictured below, not enough benefit to redo it but if I was starting from scratch I would consider it.