Irrigation

[hamesy]

I'm looking at setting up some sort of irrigation system on the allotment. There's no power or running water on site.

I've been thinking of getting a couple of car batteries and connecting them up to an on demand pump (similar to this). That will then be connected to a hose pipe.

To keep the batteries charged, I'm thinking of using a solar trickle charger (This one). The solar charger will only be connected when I'm onsite and won't be connected all the while.

Can anyone see any issues with this or even recommend a better solution?

[WendyC]

Someone on my site used a car battery to run a pump to a hose from the tanks (cattle troughs) we have on site. Have to say used to annoy me as he watered a lot and would clearly use more water than I could carry in my watering cans, and we all pay the same. Can't give you any technical answers, only that it is possible!

[polc1410]

I'm currently working on a drill powered pump that will feed from a water butt.

Battery powered drill.

[polc1410]

You will draw ~4amps running that pump.

The charger is 1.5w so in perfect (cough) sun you will give out 125mAmp. So let's say you pump water for 15minutes which would be up to 2-300litres so a lot... You would use 1ampH. You could replace that with 8 hours of perfect charging, you will generally see people say aim for 40% efficiency. So 20 hours of charging.

Realistically you will provably pump for 5mins not 15, although stop start may be less efficient. But that still means 5mins of pumping needs you to be there for 7 hours in daylight...

You would be safe with that truckle charger on a battery with no charge controller though as it won't cook a battery.

If you had the pump, the battery and the solar panel fine. Buying out right costing over £100 i guess... Seems pricey. I'm expecting to use a battery drill (£25) plus a £5 drill pump.

[Stan79]

I use a pump designed for pond water features. It's designed to work in mucky water, comes with the solar panel, pump, cables, hose adapter, battery, housing and controls. It pumps water through a standard hose and up the couple of meters onto the plot from the stream.

Worked out about £70 all in from memory. It doesn't pump huge volume of pressure but when it's sunny, it comes on automatically and just gently waters the plot from top to bottom.

Might be worth a look as it might be cheaper and better in mucky water than your planned system.

[polc1410]

Good point. That's a clean water pump. Grit in the diaphragm may stop it working. If you want a 12v specific pump looking at bilge pump may make sense.

[Alison]

From where are you intending to pump the water? You can't just pump out a water course and you say that there is no water on the site. If you are intending to harvest in tanks / butts etc then you'll need to harvest a lot to water at that rate. Personally I don't find you need to water much if it's in open beds and actually most things benefit from being treated meanly as the roots go deeper in search of a drink.

[Kristen]

From what I have seen folk posting YouTube videos they use 300 gallon/hour or 40psi pumps, and harvest shed etc. water into IBCs. All 12V from car batteries recharged by solar panels, although battery can be taken home to recharge if necessary.

I'm not sure why they use a pump as I would have thought gravity and leaky-pipe for irrigation would be sufficient (which could then be on a timer), but if you want to hand water with a hose and nozzle-attachment then that would indeed need a pump to get enough pressure.

Biggest problem, I reckon, is being able to store enough water - unless there is a stream nearby although one of the YouTubes I saw had a bilge pump in the bottle gulley of a downpipe from a building next to the allotment refilling his IBCs

An IBC is about 1,000L. I have 4,000L of water storage by my vegetable patch, filled from the house roof as well as the greenhouses, and I only use that to water with a watering can (I have mains water if I want to use the hose) but my storage still runs out in high Summer - although it fills completely in a decent thunderstorm but that would not be the case if the only collection was from a shed roof. An inch of rain on a 10' x 8' roof would be 188L, so an IBC would need 5" of rain to fill it

[polc1410]

Proper soaker pipes need more pressure than you expect to leak water out.

You could just put holes in pipe but the pressure will change considerably with 1m head on it when IBC full vs near empty. A pump would help with pressure.

4000litres... I'm impressed...

My poly gutter requires a standard water butt to be sat at ground level so even filling a watering can satvon the ground won't work if only about 1/4 full

[Kristen]

Proper soaker pipes need more pressure than you expect to leak water out.

Low pressure leaky-hose is available but, yes, I agree that regular leaky hose needs higher pressure than gravity from a low-mounted tank can provide. Another issue is how well it performs when the tank is approaching empty, and flow/pressure drops to close to nothing probably at the time that plants most need water

[polc1410]

The irrigation system suppliers are claiming drip systems use less water than even watering can. Would be interested to know especially for poly if that's true.

Like Kristen I tend to avoid watering outside stuff as I prefer plants to go getting their own water by digging deepeer. Of course we seem to be wetter up here than Kristen...

[Kristen]

Of course we seem to be wetter up here than Kristen...

I think I read that East Anglia gets less rain than Israel ... either way, its fairly dry here