Low power water wheel

[NIck 60]

I wish to build a water wheel to trickle charge a car battery to power an

electric fence.  The power requirements are quite low. (I expect 250mA?).  I

want it to be able to suit a variety of different streams, so I think an

undershot wheel on a pontoon (PVC water pipe?) set up would be best.  Would you agree?  Have you seen such a system in your experience?

Thanks, Nick

[jimovonz]

Do you even need a battery? Why not direct power the electric fence if the water supply is constant? Electric fences are typically on 24/7 and so are streams...

[ghurd]

I believe fencers are less than 250ma, maybe 50-100ma?

Small but still not very portable and it would take some water moving pretty good.

G-

[NIck 60]

The water supply would not be constant, influenced by rain events.  The battery would also maintain power to the fence during outages caused by debris, mechanical or electrical falts, maintenance, repositioning, ....etc.  

Power demands of the fences, I would assume, vary with the amount of "load"(stock touching the fence).  A battery would ensure adequate power supply, topped up from the trickle charger.

[ghurd]

And solar is a proven way to go. (seen them)

G-

[NIck 60]

I think the load would be dependant on the fence length and some instalation conditions, eg weeds, soil type, humidity? - But the less the power required the better.  So for a 50 to 100 mA (at 12V) water wheel, how big a construction am I looking?  What would be a reasonable generator to use?

[NIck 60]

Yes, I like the solar option too.  However, this is a school project and i have some guidelines to follow.

[olvvlo]

You say it is for a school project, have you thought about using bicycle wheels and gears driving a magneto Similar to that found on ignition systems for grass cutters etc.  One magnet flying past one large coil, a capacitor and contact breakers producing an output for the fence.

The reason I'm thinking in terms of bicycle parts is because whenever I have built things made using bicycles children immediately identify with it and are totally engaged.

[Nando]

Your "general" comment does not give any information for anybody to give you a practical answer.

First detail your stream or streams, their volumes and heads, also 250 ma does not say how much power you need, you need the voltage as well.

Since Electric Fences operate from different input voltages, like 6, 12, 24 Volts DC and 115 VAC.

Regards

Nando

[NIck 60]

Nando,

Thank you for your response.  I have read many of your comments in this forum and would apreciate your input.

The streams I wish to use will differ, I guess what I need to do is to design to the power requirements, and find suitable locations in streams.  As it needs to be generic, Maybe I could change gearing to cater for varying flow velocity?  The device will only be suitable for use in adequate streams.  I want it to be easy and simple to move from place to place, therefore the water wheel design rather than damming and creating a head.

I apologise for not stating power.  I mentioned a charging a car battery, these (in Australia) are mainly 12V, there were early cars which used 6V and larger vehicles which are 24V.  I assumed a 12V car battery.  

I have revised the estimate of 250mA, I now am looking at a max of 100 mA.  This would make the power requirement 1.2W.

Thanks,

Nick

[NIck 60]

Thanks olvvlo,

Bycicle wheel type arangement sounds good, maybe I could also just use a bike light generator which runs along the wheel?

I remember them, but havent seen them for years

[elvin1949]

evening

I saw one at wal-mart just a few weeks ago.

later

elvin

[ghurd]

Stepper motors.

Search the board. Lots of info.

G-

[Vernon]

I thought of the idea of a couple of 4 foot capped pieces of 4" PVC pipe for pontoons with a model aircraft propeller driving a shaft connected to a permanent magnet motor. A stepping motor might work well for this. Props are available in various diameters and pitches at low cost and the shaft could be angled to keep the motor above the deck and dry. Pile some rocks to create a high velocity channel for maximum power.