Water generator ideas

[glamsland]

Hello all you creative inventors out there..

I have this remote cabin with 800w solar and a 24v/230v/3000w inverter. kind of a modern setup in a small cabin far into the woods.. in february to september its no problem, plenty of Solar/battery power. But in the darkest wintermonths there is like no solar charging. I have a predator 3500i generator for charging. no problem..
But, I like to do some mechanics and make stuff, so I`w been thinking..;

There`s a small stream nearby the cabin, there i have made a Watermill with my kids, just for fun.
What if i make a small water generator to charge the batteries while I `m at the cabin in the dark season! THen i dont have to start the generator!
At daytime I have a average of 150-200w/h at 230v ( displayed from the victron smartshunt).
If I can charge the batteries with 100w 24/7 it will be enough for the whole week! At nighttime here`s almost no power consuption, so 100w in will be enough i think.

Why so small? Just so its easier to control if something goes wrong, I will of course have fuses all over..
Just to be on the safe side..

I can mount a 12v car alternator on the watermill, then to a12v car battery, then to a 12v/230v inverter then to a 230v/24v carger that charges the battery with like 100w/24v/8A .

its like 80m from the cabin, so its a bit long to transport DC power to the battery, therefore I think having a 12/230v inverter at the alternator , its better to send 230v thru a cable 80m long. .

THen when i leave the cabin i turn the whole thing off. cant let the watermill go the rest of the winter unintended..

any of you with experience with alternators? do I need a car chargecontroller for it? or maybe it will be good enough with a Victron DC-DC 12-12?

other ideas?

 

[12VoltInstalls]

THen when i leave the cabin i turn the whole thing off. cant let the watermill go the rest of the winter unintended

Why not? I’d keep it charging but turn off the inverter

any of you with experience with alternators? do I need a car chargecontroller for it?

what you want is an internally regulated alternator. And I’d try to use a smaller one at 50-60A if possible. You’ll need one small fla battery at the water wheel imho. Then the inverter output has a nice buffer.

can mount a 12v car alternator on the watermill, then to a12v car battery, then to a 12v/230v inverter then to a 230v/24v carger that charges the battery with like 100w/24v/8A

You’ll need adequate vertical ‘drop’ or ‘head’ as well as the CFM of flow to make ~2-3HP of potential.

You might be better off with a microhydro unit if head and flow aren’t ideal and something of a charge controller to cut out the inverter when the buffer battery gets low so that it can recharge and output useable voltage to the charging scheme you mentioned.

 

[glamsland]

Thanks for answer.
The wheel are 1.5m in diameter, so its got alot of power with all that water pulling.
And i was thinking about this gear unit from Aliexpress, the waterwheel dont go fast, but its powerful, so the gear ratio fits fine.

 

[12VoltInstalls]

I’m not an engineer. Have a bit of theory knowledge, though.

If head doesn’t exist, a water wheel can work but it needs a lot of CF/S to put the effective energy in the range that head(pressure) would make in foot-pounds, less spillage, horsepower-to-horsepower.
An alternator might provide too much ‘braking’ to maintain the power potential at 1 gallon per second. (From looking at your design I just guessed at your flow)

I might see if I couldn’t transport more water volume from higher up if you have that capacity, build a larger wheel (10’ diameter?), and have the raceway feed the buckets in the same direction as the kinetic energy, and employ a diverter at the end of the raceway drop so that in periods of high flow the water doesn’t overshoot the buckets.

And that’s about all I know on the subject.

Well not all- a smaller ‘motor’ (alternator) might be better to produce power? Not sure. But an automotive alternator can present a 1.5-3.x+ horsepower load to its mechanical counterparts and you only have 1/15th of a horsepower available on the existing design.

 

[ksmithaz1]

I looked at this ages ago before solar was a thing ... Looks like it's still alive

Micro-Hydro Power: A Beginners Guide to Design and Installation – ATTRA – Sustainable Agriculture

attra.ncat.org

It's all about volume and gravity, but if memory serves you really can't get much unless you have a pretty good sized flow that drops 30 feet or so. Then of course you will have to deal with the environmentalists.

 

[12VoltInstalls]

Then of course you will have to deal with the environmentalists.

Just use a stream that has pure water, not polluted with environmentalists.

 

[efficientPV]

I would never use a car alternator. That just wastes power driving the field winding. A DC motor with magnets like treadmill would be much better.

 

[ksmithaz1]

You can get a water-wheel from Ebay for $100 or so. They are designed for landscaping to run some LED lights or something. If you want to get up in the 500-1000W range you are going to need a 50-100' drop on a 2" pipe into the turbine. That means a a catch at the top of the slope with a filter/screen to keep the crap out, that dumps into a reservoir. Plumb the basin down to the turbine, and dump the outlet it downstream. Now you get to wire it out to something useful however far away that is. After you expended al that effort building a filtered catch basin and plumbing it out you might get 500W if you can trap enough of the water flow without PO'ing some environmental outfit. Further you now have a periodic chore of cleaning off the screens and such. You ever have a boat? This will be worse and you won't be able to ski behind it.

It's one of those things that seems like a neat idea until you start looking at the logistics. Now if you can dam up something that's going to hold 10+ acre-feet of water, maybe you can get some actual power out of it, but not enough to get an ROI. Dams suck. I've been involved with a number of small broken dams. I went back over to Hope Mills,NC last time I was out that way. What a fiasco. Also had a dam break in a neighborhood I lived in. That was a nice assessment we all got to pay as well. County was not real helpful. To get power the water has to have enough pressure to spin the turbine.

If'n you just want to putz around grab a water-wheel from Ebay. That will curb your desire.

 

[Warpspeed]

I can mount a 12v car alternator on the watermill, then to a12v car battery, then to a 12v/230v inverter then to a 230v/24v carger that charges the battery with like 100w/24v/8A .

Car alternator would be about the worst possible choice for something like this.
A 12v vehicle alternator needs to turn at usually about 2,000 rpm just to reach charging voltage.
No problem when belt driven from a 200Hp car engine, with a pulley step up ratio of 3:1 to 4:1
Much more difficult to reach the required rpm from a small hydro !!

A far better approach would be to use a high voltage treadmill motor.
You should be able to find one that runs from 180v and runs at perhaps 4,000 to 6,000 rpm.
Output voltage when used as a generator is proportional to speed.

If you drive one of those at about one twelfth the rpm, you get about one twelfth the voltage.
Something like 15v at 333 rpm to 500 rpm would be much more realistic.

Or 30v output to charge your 24v battery direct, at about twice the above rpm.

A super quick two minute search of e-bay turned up this:
https://www.ebay.com.au/itm/285357774322?hash=item4270a615f2:g:vVsAAOSwKW5er2TX&amdata=enc:AQAIAAAA4DXOqg1aHzyfNZGAwh4A0GWmVhKaoO/WjdUNqfCv8E47Ja9G2bq3UrOLMqlIul1sTjHPonlaqzwYNYTDC3VFIZsB4RZpRsduTI5Qh9cCJNa70p3m/2ZFBWuJyip4x/obfeWVWaABarGmdFBNcJKLo2lnEJnoiemXE11Cdl5X0FNAISxXunFcqKXz9cSrobGrblGNM4a9HLOi5FE6VDa7wRQvJtZD6iVugHKfwVSeqlepnJDLp8jrBGAMSrfO7cK42ZLV2ME2oYI+3/8Govkasg7Oa9yYYMXPk0ugbHcPfTQ3|tkp:Bk9SR-ye5cCtYw
180 volts at only 3,600 rpm.
At one twelfth speed, 15v at 300 rpm or 30v at 600 rpm.

Not suggesting you buy this (its in Australia) but look for something similar, high voltage, at lowest rated rpm.

 

[Doggydogworld]

Some DIYers convert old washing machines into hydroelectric generators.

 

[Bop]

Car alternator would be about the worst possible choice for something like this.
A 12v vehicle alternator needs to turn at usually about 2,000 rpm just to reach charging voltage.
No problem when belt driven from a 200Hp car engine, with a pulley step up ratio of 3:1 to 4:1
Much more difficult to reach the required rpm from a small hydro !!
snip

Not suggesting you buy this (its in Australia) but look for something similar, high voltage, at lowest rated rpm.

Hang on- Warpspeed????
Is that you from the backyardshed place???

Microhydro is fun- if you got the water... (not much of it around my place...)
Two types- pelton wheels need a drop as 12VoltInstalls mentioned, but 'flow of the river' is also possible in larger rivers with no drop at all (basically big paddlewheels)- there was one in Northern NSW that was on one of the local rivers- was about 10m long, slung under a dock the owner used to moor his boats on- it turned slow, but man- it literally twisted a 2" steel bar at the drive end one time when the drive rim to the alternator got jammed by a tree in flood waters- the drive pulley stopped turning, but the paddle wheel didn't... (it had a simply ridculous ratio on it- the drive pulley was about 1.5m in diameter, to pretty much the smallest pulley I have ever seen on a Bosch alternator (24v)
Driving past- you couldn't even see it was under there....

 

[12VoltInstalls]

small stream nearby the cabin

What are your thoughts on all this entertainment regarding your water wheel?!

literally twisted a 2" steel bar at the drive end one time when the drive rim to the alternator got jammed by a tree in flood waters

That’s like 4000ft.lbs to get close to mild steel shearing. I can’t remember the calc but that’s like 200HP I’m thinking.

So the waterwheel must have had a pretty incredible flywheel weight. Cuz that’s like 150kW of stored power to accomplish that feat! There’s a principle where equivalent horsepower at a lower rpm versus a higher rpm represents an exponential increase in torque. There must have been a ginormous surface area.

 

[Warpspeed]

Hang on- Warpspeed????
Is that you from the backyardshed place???

Yes, I have to plead guilty as charged Bop )

 

[Bop]

Yes, I have to plead guilty as charged Bop )

LOL- Boppa from there ;-)
People ya meet on the web... lol

 

[Bop]

What are your thoughts on all this entertainment regarding your water wheel?!

That’s like 4000ft.lbs to get close to mild steel shearing. I can’t remember the calc but that’s like 200HP I’m thinking.

So the waterwheel must have had a pretty incredible flywheel weight. Cuz that’s like 150kW of stored power to accomplish that feat! There’s a principle where equivalent horsepower at a lower rpm versus a higher rpm represents an exponential increase in torque. There must have been a ginormous surface area.

We are talking about a 10m (30ft) plus long paddlewheel about 2.5m/8ft in diameter in flood waters...

Turns slow- but jam one end of the axle where the drive cog for the belt was and let the wheel keep turning and well- there's a lot of force against it...
(the drive cog/pulley itself was huge- an old steel wheel almost the same size as the paddlewheel itself, with a massive belt (in length, not thickness) that went around it up to a pulley on a car alternator about 5cm/2" in diameter- and then jam a tree in between that big pulley and a dock support so its stuck, and there is still floodwaters pushing on the paddlewheel itself...)
It took two trawlers to remove the tree afterwards- and that was after the floodwaters had subsided...