Home made hydro help

[SteveB]

Hope someone can help me, I have built a home made hydroelectric system. However I don’t seem to be able to produce enough power to charge my 24V AGM batteries. My main power is from Solar , but I live in N Spain where I can’t rely on the sun .

So I live in a mill , which has a 3 M water shoot from a canal . The water is flowing enough to turn the wheel 15rpm . I have another wheel that has cogs ,that then turns a small cog wheel 11-1 ratio.
Attached is a 42 toothed bicycle sprocket.
I’ve taken off the blades from a 24v 800w wind turbine generator. On this I’ve put a small bicycle sprocket, with a ratio of 4-1.Giving me a total Rpm of 660.

It is 3 phase Ac , which passes through a charge controller converting to Dc .

With no load it rotates faster giving me a 3 phase V of 36v

So as soon as I put it on the load it slows to the speed I have mentioned, and only produces 20v .

From my description does anyone have an idea , what is wrong ? Quite possibly it’s me a novice at all this ! Or another cause ! From my research 660rpm should produce enough power to charge the batteries.

I can’t speed the water wheel up anymore, the only thing is to change the gearing if that seems the problem!

Look forward to seeing your comments, and ideas

Steve Spain

[Mary B]

Smaller generator to match the available power...

[Vortechs]

The friction losses from all that gearing could be eating up a lot of your potential power. I don't know the generator you're using, do you know the rpm range it's designed to charge at? A smartdrive might be better as they can be configured to charge at quite slow speeds.

Are your AGM batteries good? What's their standing voltage? Are they the load you're connecting when getting 20v?

Got any pics?

[mab]

Power is proportional to the vertical height that the water falls whilst on the wheel;
 It's also proportional to the quantity of water going over the wheel. Doing a rough calc for a 3m overshot(?) Waterwheel and arbitrarily assuming 10l/s flow: 10 litres per second should give you around 100w out of the wheel, then you lose some in your 2 stage gearing up: if the bearings are good and it's not completely gunged up with grease i might expect at least 50w out.

You don't say what load you're using that drops the voltage to 20v? Nor how many amps you get at 20v? If the unloaded voltage is 36v then it should put something into a 24v battery as is.

[joestue]

Call up hvac companies and get a dead 1hp 1250rpm ecm fan motor.

Reconfigure the coils from 4s -Y to 2s 2p Y or 4s Delta or 2s 2p delta... As needed, to get the load and charging voltage you want.

Most of the ecm fan motors will either need new bearings, or glue the magnets back on, or there is nothing wrong and the vfd is what failed.

They are just about the most efficient commodity motor generator available

[SteveB]

Thank you for your advice.
I don’t seem to be able to down load some images! Would a belt and pulley drive be more efficient?
Also would a different ac to dc charge controller ( solar/wind hybrid) make any difference?
Reading about micro wind generators, at 550-700 rpm they should be producing 24+v and 4-500w
At the moment I’m producing 20v , 20w and 0.95amps. U

This is all new to me , if I can answer any more of your questions, I will try to .

Thanks again

[Vortechs]

How are you measuring the rpm?

There's info on the smartdrive motor/generator that I'm using for my hydro here:
https://www.powerspout.com/collections/smart-drive-d-i-y I don't know the hvac one joe is recommending so that might be better.

You should have a bridge rectifier that converts the ac to dc between the genny and batteries. Then a charge controller that's connected to the batteries that regulates the charge of the batteries and dumps any excess to a dump load - is that what you have?

[joestue]

The motors im talking about look like this

https://www.ebay.com/itm/134000640101.

For the 20 watt territory, you could probably get it efficiently with a 3:1 speed increase from a 15rpm waterwheel.

[mab]

You cannot determine power from speed alone: 660 rpm unloaded will give you your open circuit volts - 36v as you mentioned.

As you have observed, as soon as you load the generator it slows down - this is expected as the generator is taking energy out of the wheel. If you connect your d.c. output to a 24v battery it will slow down until the generator is outputting 24v, probably at about 0.8A as it stands.

You're getting about 20w into your load, but without knowing what  quantity of water is flowing onto the wheel or the actual diameter of the wheel we can't know how much power you should be getting:- there might be nothing wrong; 20w might be all there is, and improving the efficiency of the drivetrain will only gain you a few watts.

Put a 3 gallon bucket (or whatever size you have) under the chute and time how long it takes to fill.

[joestue]

20 watts is .7 liters a second falling 3 meters.

[machinemaker]

can you change the windings in the generator to a smaller diameter wire and more turns? This should get you a higher voltage. OR if you are interested in building a low-head turbine this is a good paper. www.picohydro.org.uk/docs/pico_propeller_guidelines-April2011.pdf
kent

[Vortechs]

That link wouldn't work for me but this one does: https://www.picohydro.org.uk/docs/pico_propeller_guidelines-April2011.pdf

Good website, never seen it before.

[SteveB]

If I had a lower powered generator ! Instead of a 800watt /24v generator,
Would a 400watt / 24v generator work better with a 25/35 litre per second water flow, from 3m?
Also the water flows down a sloping wall, should I concentrate the water into a pipe to reduce the resistance?
Any thoughts?? Please 🙏

[Bruce S]

SteveB;
I'm certain that even the 400w gen will give you the same issues.
Can you give us the maker/model or Specs of the two Gens ?

There may be an RPM that gets you up to the voltage output under a load you need.
I agree with others here there's either too many loses from all the step up sets.
The 660 RPM ? is this the RPM needed according to the 800w gen?

Bruce S

[joestue]

If I had a lower powered generator ! Instead of a 800watt /24v generator,
Would a 400watt / 24v generator work better with a 25/35 litre per second water flow, from 3m?
Also the water flows down a sloping wall, should I concentrate the water into a pipe to reduce the resistance?
Any thoughts?? Please 🙏

At 2.5% efficiency you have a lot of other things to figure out first before you get to the generator.

Yes the water wheel will slow down under load, potentially a lot more than 50%. Depends how big the buckets are.

[mab]

25 - 35 lps at 3m head is a nice resource to have.

In my experience a bigger generator tends to be more efficient so i suspect you're better off with the one you have.  (unless the smaller generator needs fewer rpm for 24v, allowing reduced gearing - but i doubt that would be the case).  Granted at 20w the efficiency benefits of a bigger genny won't be apparent, but it ought be possible to get more power with that much water.

...Also the water flows down a sloping wall, should I concentrate the water into a pipe to reduce the resistance?
Any thoughts?? Please 🙏

Difficult to advise without seeing it - but I'm not sure if you can post pics if you're new here.

Do you mean that part of the 3m is with the water flowing down the sloping  wall before falling on the wheel? That would waste a lot of energy if it's how I'm imagining it, (but I'm not sure a pipe would be better), letting it freefall might be better, but might make it splash around when it hits the wheel.

Is it an overshot waterwheel you have? With buckets to hold the water?

[mab]

...
So I live in a mill , which has a 3 M water shoot from a canal . The water is flowing enough to turn the wheel 15rpm . I have another wheel that has cogs ,that then turns a small cog wheel 11-1 ratio.
Attached is a 42 toothed bicycle sprocket.
I’ve taken off the blades from a 24v 800w wind turbine generator. On this I’ve put a small bicycle sprocket, with a ratio of 4-1.Giving me a total Rpm of 660.

It is 3 phase Ac , which passes through a charge controller converting to Dc .

With no load it rotates faster giving me a 3 phase V of 36v

So as soon as I put it on the load it slows to the speed I have mentioned, and only produces 20v .

I think i misread your original post before:

If I'm reading it right now you're getting 20v 1A at 660rpm, and open circuit at 36v it's spinning faster.

This suggests to me that really wants to be spinning faster for power at 24v, and higher gearing may be necessary (or better: a lower rpm generator).

Is there a power/rpm/windspeed chart for the original wind generator?

Did it ever produce good power as a wind generator?

[joestue]

Sounds like this guy has a kilowatt of hydropower theoretically available.

I built a cross flow turbine using 24 strips of steel 2 inches wide cut from the side of a 16" diameter hot water tank.

The strips of steel were welded to the sides of 2, 12" diameter 24 tooth skillsaw blades, with a shaft bolted to thr blade through thr center hole.

One of the shafts was 1.5" diameter aluminum running on a wood v block lol, in one night it eroded like 1/16th of an inch off the aluminum.

10 feet isnt typically considered enough for a cross flow turbine, but 25 liters a second falling 10 feet should be enough to get 100 watts out of a 1 foot diameter cross flow turbine at several hundred rpm.

For the other side of the turbine, it hung from the generator by a v belt. No bearings needed other than in the motor

We were getting 50 watts out of a lot of water (1 to 2inch thick stream, 2 feet wide) , falling 1 foot plus 1 foot for the diameter of the turbine)

[Adriaan Kragten]

There is a simple formula to calculate the potential hydraulic power Phyd available in the water. This formula is: Phyd = ro * g * H * q    (in W). ro is the density of water which is 1000 kg/m^3, g is the acceleration of gravity which is 9.81 m/s^2. H is the height difference in between the high water and low water level in m. q is the flow in m^3/s.

So first you have to measure the height H and the flow q and then you can calculate Phyd. Your water wheel or water turbine has a certain efficiency and this reduces the mechanical power coming out of the water turbine. If you use a transmission, this transmission also has an efficiency and this reduses the mechanical power coming out of the gear box. The generator also has a certain efficiency and this reduces the electrical power coming out of the generator.

To get maximum electrical power, the generator has to match well with the water turbine. This problem is explained for a wind turbine in chapter 8 of my public report KD 35. For a water turbine, you must follow the same procedure. This means that first you have to determine the optimum cubic line of the water turbine. Formula 8.1 of KD 35 is the formula for the optimum cubic line. Next the generator has to be loaded such that the Pmech-n curve of the generator lies as close as possible to the optimum cubic line of the water turbine. I have followed this procedure for a small water turbine in public report KD 598. However, I used a water turbine for which the characteristics can be determined easily and a generator which has been measured for different load conditions. If you don't know the characteristics of your water wheel and your generator, it will be a process of try and error.

All my public KD-reports can be copied for free from my website: www.kdwindturbines.nl at the menu KD-reports.