Using a pump as a Generator

[Bill Richardson]

Can I please seek advice. I know little about this subject. I would like to use water power to generate enough electricity to run an electric fence (3 lines x 250m) for a pig enclosure.   The water source (small stream) isn't huge and the head of water that I can muster is only about 1.5 metres. Through research I see folks using pumps (as turbines) to generate power. My question is - would it be possible to use a 12v caravan pump as a small turbine fixed to a water wheel to charge a 12v deep cycle battery - a kind of trickle charge. If it was possible what else to I need?

Many thanks,

Bill  

[Flux]

At the low power levels that you are thinking about I doubt that you will have any luck using a reversed pump. On a larger scale it is certainly possibles to use reversed pumps as turbines.

At small scale the efficiency drops so low that I doubt that a dc pump would even motor with 1.4m head. The flow rate would be so small that you would be looking in the milliwatt region.

If you have a decent flow than at 1.5m head you should be able to generate enough power to run your fence, but I think it unlikely that you will find a suitable standard pump unit.

If you want to do this then I am sure it is possible with a Banki or turgo turbine but you are in for a fair amount of work and it may be more than you are prepared to put in for such a small power output.

Flux

[Bill Richardson]

Thanks Flux,

Will you please have a look at this link its really interesting - is this a possibility?  I may be able to get a little bit more flow to at least make it reasonable.

http://www.reuk.co.uk/Building-a-Waterwheel.htm

Best wishes,

Bill

[chainsaw]

I have used solar fence chargers with good results. If you have decent solar exposure these units are hard to beat for their simplicity and cost. No maintance other than battery replacement after several years.

[Flux]

At 1.5m head you will need something in the region of 10gpm flow to be worthwhile trying. If you can get that then you should be able to do it.

A waterwheel is not an ideal choice but if you are good at woodwork then it will do fine. You would do infinitely better with a decent low speed permanent magnet alternator rather than that high speed modified car alternator. If you are short of water you need to loose as little as possible in speed increasing transmissions and alternator iron loss.

Look at the Otherpower site and see if you can find the article on water power ( Scott's turbine ?). The alternator they used would be far better than the modified car thing and you could manage with one stage less of gearing. For an electric fence you could manage with less magnet in the alternator.

If you kept the same magnets and increased the turns you may even manage direct connection to the water wheel and still get the few mA needed for a fence.

Flux

[thefinis]

I second this option as I have used many different solar chargers and electric fence combinations. Fences use most of their power if shorted so a very small recharge is needed unless weeds, downed wire, etc have the fence grounded out.

Penning pigs next to a running stream of water may not be so great of an idea. Fencing to keep them away from running water is a great idea.

Finis

[Bill Richardson]

I thank you all.  Time for me to have a re-think maybe.

Best wishes,

Bill

[ghurd]

I think it is a doable project (not with a pump), just because of the very low power they take.

A decent stepper motor may make enough.

A small solar panel would be a lot easier.

G-

[Ganderwings]

Hello Bill,

How big is your small stream? The 5 foot head is not bad for m-amp battery charging even if you use a small plastic pump sized to your gallon/per minute flow, although those pumps are not efficient. You would probably be better off using a squirrel air fan driving a stepper motor (see:

http://www.thebackshed.com/windmill/

coming close to a crossflow turbine if you don't want to go through the effort building a proper crossflow turbine for your stream, see my Webpage:

http://www.fight-4-truth.com/Alternative%20Energy%20Page.html.

It just depends how much effort you are willing to spend.

I use a fencer myself running it at night against bears and deer, shutting it off in the morning to charge my one dollar 12V deep cycle battery with a dinky 10 x 14" solar panel, which works like a hot dang. Watch the ground rod/cop.tube, it must be in wet ground. Install the fencing wires alternatively, hot, ground, hot, ground, which is very effective on dry soil especially. See my other page just above INDEX NO. 5--- text about my one dollar battery:

http://www.fight-4-truth.com/Parts%20Page.html

You can not draw current from a battery while under load and keep your battery alive, which is the reason car batteries do not last, hence in your daylight case you would use two batteries while the one is running the fencer the other is charged with solar power using a double through switch.

In the other hand if you like challenges, then build yourself a small Bedini battery charger which, runs itself off of a 30.00 dollar (CA) garden tractor battery and forget the hydro problem. It will charge its own battery and also charge your fencer battery. Again thumb through my WebPages, the info is all for free:

http://www.fight-4-truth.com/Work%20Shop.html

http://www.fight-4-truth.com/Schematics.html     INDEX:  oo Monopole magneto 11a

Cheerio,