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I am working on a small project where I, from a relatively confined space in a well that has a diameter of 30 cm, will need to transport the water upwards about 2 meters.

I have been looking at ram pumps but cant really see a way to utilise that as i dont have a "higher" water source. I have also been looking at electric pumps on Alibaba and it seems that i'll land at around 2W, which seems like a lot for an iot device - i really dont want to have to recharge the device every week, esp. since there is little energy to harvest nearby.

The requirements are:

  • Ability to pump water upwards 2 meters
  • Flow of around 12 liters per hour would be enough
  • Ideally 12V or lower

What are the best options? :) I know that product recommendations are not allowed, but what techniques should I look at overall? Is there a resource somewhere that compares the efficiency of different pumping methods?

[EDIT] RE comments: In terms of effeciency, I mean as low wattage as possible. I wont have easy access to recharging (solar and wind are out, but potentially the energy of the water flowing down into the well could produce a minor charge for the battery). If we can get to a point where the battery only needs to be changed once a month, that would be perfect.

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  • $\begingroup$ Define your concept of efficiency : wind free & day night when blowing , sun day only except for clouds etc etc $\endgroup$ – Solar Mike Aug 30 '17 at 6:33
  • $\begingroup$ Someone knowledgable should chip in: the head is small, so little pressure = little torquue or force produced by pump's motor. Whith what kind of DC motor does this mean less current draw than the nameplate capacity? $\endgroup$ – mart Aug 30 '17 at 7:25
  • $\begingroup$ What hasn't been mentioned & it could be important, is what happens to the water after it has been pumped upwards by 2 m? Does it discharge into a tank or would the pump need to push the water through a pipe or network of pipes? $\endgroup$ – Fred Aug 30 '17 at 12:03
  • $\begingroup$ Seems like any standard pump, a solar-charged battery, and a controller that activates the pump for a minute out of an hour. Maybe an extra reservoir above, to collect water to provide supply over night if required. $\endgroup$ – SF. Aug 30 '17 at 12:24
  • $\begingroup$ Thanks for the comments! I have edited the question, but @mart is right - We're looking for something with as low power consumption as possible. $\endgroup$ – Jeppe Mariager-Lam Aug 30 '17 at 13:19
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12 liters per hour and 100% efficiency is:
12l/hr * 1kg/l * 1hr/3600s * 2m * 9.81m/s^2 = 0.0654 Watt

Best case efficiency on a pump this small without a military budget will probably be 25%.

To operate for one day on a 12v battery you would need:
(0.0654w/12v)/0.25 * 24hr = 0.5AmpHr/day

I don't know the details of your setup, but it would probably be more efficient (for the cost) to pump one liter up to a gravity holding chamber (perhaps with a level switch) 12 times a day, rather than run a very tiny pump continuously.

A very small centrifugal pump or diaphragm pump would probably be your best bet for the low head application. A brushless centrifugal pump will generally have higher efficiency if you can find one small enough.

If there is any available light (even indirect), solar may be applicable for this low demand application.

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Consider a bucket-and-chain pump, as depicted from this page.

The advantages are that operation can be intermittent, priming isn't a problem, and the pump will work with a low battery, as long as the motor turns.

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Does the battery need to also fit down into your well area? If not, you should then just be able to get a large battery (i.e. car battery or marine deep-cycle) that may have capacity for a month at a time. Then at your once-per-month changeout switch the battery out with one that's been trickle charged over the month in another location that does have solar/wind/hydroelectric.

Another thing to look at is whether you could use smaller pumps with less capacity/power draw in cascade where each one wouldn't need to pump up as high, reducing their power requirement.

Just make sure to fuse it appropriately as car batteries can provide A LOT of current.

But overall, you have a certain amount of work that has to be done (raising a volume of water up a given distance). There is a set minimum amount of power required to do your work, no matter how close to perfect efficiency there is in your lift mechanism.

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