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weswooly
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Joined: 02/09/2017
Location: Australia
Posts: 4

Posted: 05:26pm 02 Sep 2017

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Hi All,

I have been an occasional visitor to the site over the last few years and have been contemplating building a micro hydro generator from a F&P smart drive for some time now. I just happened to see a F&P washing machine on the side of the road the other day, which I have now disassembled and which has motivated me to finally begin my project. Its 42 pole but I haven't got my callipers here so haven't measured the wire but its either0.6 or 0.8mm. Being forever short of time, I thought it wise to ask advice before starting out to help me avoid mistakes as much as possible, although I am happy to experiment and figure it out along the way. I'd rather build the setup than buy it as I enjoy the challenge!

My situation is that I want the hydro system to boost power generation, particularly in winter, when successive cloudy days reduce the power I get from an existing self-assembled off grid solar power/battery bank system on a farm. It is used to mainly keep a fridge running in my shack when I'm not there, and power lights etc as well when I am there. I have a 48V battery bank powering a 4kW inverter-charger, charged by 6 x 200W Solar panels.

My water supply is a large spring and creek-fed dam, which overflows year round, and has a 5m drop on the down stream side, in just a few metres of horizontal distance. In winter the overflow is around 6-10 l/s. In summer it drops to about 1-2l/s, however I don't really need the additional power in the summer. I have been gathering materials over the last 2 years and now have sufficient length of 75mm internal diameter rubber pressure hose and a 75mm valve, which I intend to bury thru the dam wall (to avoid a siphon and possible air pockets and power loss etc).

Using various online calculators I have gathered that with the 5m head, flow of approx 5 l/s, and fairly short pipe of around 15-20m max, that I can produce around 6.3 psi, and generate between 50-90Watts depending on the final flow rate.I would be happy with even the low end of this. Over 24 hrs this would be 1.2kw and adequate power for my needs.

The battery bank is located approximately 100-120m from the hydro plant site.

My inverter-charger has a variable AC input that I believe could allow my to supply AC to it from the water turbine to charge the batteries, otherwise I could generate DC and charge the batteries separately. I haven't looked into this aspect yet so any advice here would be appreciated. I think lower voltage DC is probably safer and my preferred option. However I would then need thicker transmission wires, which I am yet to source. Advice on charge regulators would also be appreciated. Is it ok to have one inverter-charger and another power source connected to the same battery bank?

From my (admittedly limited) understanding, I also need to calculate or estimate the final RPM to chose a suitable wiring configuration for the stator. Since I haven't built the infrastructure yet, is there a way to fairly accurately calculate the expected rpm using the data provided above?

Also as once started the rotor wont be stopping and starting like it would for a wind turbine, so I suspect cogging isn't as big an issue for a water driven setup. It will be turned on after the first heavy rains and off again when the flow rate is too low.

Any advice or suggestions would be greatly appreciated. Thanks in advance!

Wes

yahoo2

Guru

Joined: 05/04/2011
Location: Australia
Posts: 1166

Posted: 05:03pm 07 Sep 2017

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Hi Wes,
its been a long time since I have worked on this sort of setup, I can try and give you some pointers about how we "used" to do it.

I found the simplest way is to run a 3 wire cable and leave it as AC until you get to the battery shed then fit the rectifiers, voltage control and diversion load. I have worked on a few chinese wind turbines set up this way and it works well.

There can be some fighting between the controller and solar charger depending on how the diversion load is wired but that is not hard to get around.

the biggest issue you will have to work with is getting the water to do what you want and get that wheel spinning properly. Multiple nozzles, fine adjustment, tricks to get the water away, whatever it takes.

The problem is voltage, the potential DC voltage at the battery (minus the diode voltage drop, minus the cable resistance) has to be higher than the battery voltage for it to charge. The turbine has to also overcome mechanical friction and drag. With a wind turbine controller that has a readout of the AC voltage you can see the blades freewheeling in the breeze and watch the voltage not quite making it and the amp meter staying on zero then a gust of wind will come along, it will jump over the battery voltage thresh-hold and the ampmeter will jump into gear. You dont have that luxury, the skill you put into the build has a larger effect, there is not many windy days with a hydro system.

There is a simple bit of calculation somewhere on the interweb that explains this concept and calculates the amps.

I will see if I can find it for you. No, its gone

Pity, it was a really good resource.

I think it goes,
line voltage minus battery voltage divided by circuit resistance equals amps output

rough example
a turbine at 1000 rpm @ 0.1 volt per rpm
battery voltage of 57.6 volts
generator circuit resistance of 1.5 ohm

(100-57.6)/1.5 = 28 amps @ 1000 rpm @ 57.6 volts DC battery

if the turbine cant maintain that load at that rpm it will stall down to something that it can so you have to change the circuit resistance to hit the sweet spot of rpm and amps for your expected flow.
Cheers Yahoo

I'm confused, no wait... maybe I'm not...

weswooly
Newbie

Joined: 02/09/2017
Location: Australia
Posts: 4

Posted: 05:22am 10 Sep 2017

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Thanks Yahoo for the helpful information.

plover

Guru

Joined: 18/04/2013
Location: Australia
Posts: 302

Posted: 03:09am 11 Sep 2017

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yahoo2
Now and then I stray outside the microprocessor area, like now in this thread.

Quote I will see if I can find it for you. No, its gone Pity, it was a really good resource.....

Are you saying something on the internet has gone that you have seen. If that is the case all is not lost. You can do time travel in the Internet data base, by using the so called "waybackmachine', use the link:

https://archive.org/web/

If you know the url of something that used to exist, the web information may have been archived as long as it has not been deliberately barred.

davef
Guru

Joined: 14/05/2006
Location: New Zealand
Posts: 499

Posted: 12:47am 21 Sep 2017

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I use one of the older F&P washing machine motors ("Gentle Annie") to generate 3.5A or 5A into a 26V LiFePO4 battery, for back up. Trying to get a Smartdrive to operate at that low power level is problematic. At the URL below you should find some docs suggesting removal of a number of the coils on a Smartdrive to increase efficiency at such low power levels.

As yahoo suggested I also run 3 core mains cable about 100 metres up to the battery box. I use a 3 phase bridge rectifier and no charge controller, as I just stop charging at a certain voltage.

I bought the spoons from powerspout and made my own hub. Single jet mounted on a 50mm butterfly or ball valve.

Unloaded the generator puts out about 50VDC, think I read somewhere that when loaded if the voltage drops in half (25VDC) that you have it properly loaded.

The real challenges are keeping debris out of the intake system and if you want to run it 24/7 then consider how you are going to replace bearings. My Gentle Annie unit is modified so that I can easily replace bearings and use a trantorque to attach the hub to the shaft.

Good luck!

Edited by davef 2017-09-22

Dinosaur

Guru

Joined: 12/08/2011
Location: Australia
Posts: 311

Posted: 04:16am 08 Oct 2017

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Hi All

weswooly just reading your post and the replies, prompted me to exit my "Read Only" mode and make a suggestion that may be way out there but could prove useful.

Instead of using the continuous flow of water, why not build a small reservoir that when
full discharges into your turbine via a larger pipe, until it is empty.
Then the turbine would free wheel for a short time and stop. Repeat the cycle when the reservoir is full again.

Perhaps the issues mentioned in the other posts will be minimised.

Regards

Regards
Hervey Bay Qld.

weswooly
Newbie

Joined: 02/09/2017
Location: Australia
Posts: 4

Posted: 12:42am 09 Oct 2017

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Thanks davef and Dinosaur for your comments.

Davef: did you mean by "URL below" the powerspout website?

Dinosaur: Not a bad idea which would allow the system to run even in summer when the flow rate slows down.

Cheers

davef
Guru

Joined: 14/05/2006
Location: New Zealand
Posts: 499

Posted: 10:31pm 12 Oct 2017

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Yes, powerspout. He had a lot of information on his old website (ecoinnovation), I am not too sure what is available on the new site.

Clockmanfr

Guru

Joined: 23/10/2015
Location: France
Posts: 429

Posted: 05:21am 13 Oct 2017

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Try ,,,, http://scoraigwind.co.uk/wp-content/uploads/2016/07/PS-all-Getting-Started-Nov-15.pdf

This guy loves em, he is Scotland, UK, lots of water in Scotland.

Everything is possible, just give me time.

3 HughP's 3.7m Wind T's (14 years). 5kW PV on 3 Trackers, (10 yrs). 21kW PV AC coupled SH GTI's. OzInverter created Grid. 1300ah 48v.

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