6 gpm DC pump for 24-hr operation

draines
draines Registered Users Posts: 17 ✭
in General Solar Power Topics #1

Hello- I looked for other threads with this discussed but didn't find one that I could use. I have a local farmer who wanted to run his 6 GPM water pump 24/7 through the winter months. He does this for cattle troughs to keep the water from freezing. He currently uses batteries charged at home and delivers a new battery each day. The pumps he uses now are around 14A and the batteries/panels for that amount of power is more than he wants to pay for.

Are there any lower amp pumps available that are in DC that would allow him to skip an inverter and run straight from the batteries/panels at less than 14A? I see some Flojet pumps, etc., but I am not familiar enough with the specific types of pumps (diaphragm, centrifugal, etc.) to know what types would be good.

I did tell him to try use other methods such as heaters or passive designs, but he knows his current method works and he wants to keep using batteries. I just thought it was an interesting problem to help him with. 

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  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    #2
    Need much more detail... where is the pump?  Does it need freeze protection?

    Most important in calculating the power draw (and type of pump) is knowing the pressure that the pump must produce in order to get 6 GMP flow.  

    If you are using the pump to pressurize a 60 psi air bladder tank, 6 GPM will take a lot of energy.  On the other hand, if you are using a low pressure circulator pump to keep water moving in a stock tank, then that same 6 GPM will take much less energy.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
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  • draines
    draines Registered Users Posts: 17 ✭
    #3

    The current pump is exposed and does not freeze, and it may just be in a small unheated box. The pressure (psi) will be close to 0 as it is only pumping into an open-toped water trough. I think your "low pressure circulator pump to keep water moving" is the accurate description. I see some pumps like the http://www.pumpvendor.com/Jabsco_82600-0294.html that move 6 GPM at less than 2Amps when pressure is near 0. I'm not sure how realistic this is though...sounds too good to be true?

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  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    edited November 2015 #4
    draines said:

    The current pump is exposed and does not freeze, and it may just be in a small unheated box. The pressure (psi) will be close to 0 as it is only pumping into an open-toped water trough. I think your "low pressure circulator pump to keep water moving" is the accurate description. I see some pumps like the http://www.pumpvendor.com/Jabsco_82600-0294.html that move 6 GPM at less than 2Amps when pressure is near 0. I'm not sure how realistic this is though...sounds too good to be true?

    Sounds about right.  I've got a 12 volt computer fan that pushes 40 cfm and only draws 3 watts.  But it cannot produce enough pressure to get 40 cfm through 20 ft of 4" pipe.

    Circulator pumps are similar.... they can't tolerate too much resistance (filters, valves, thin pipes, etc).

    As your pipes begin to freeze (from the outside) the water current is constricted to a smaller diameter and the circulator pump may not be able to keep the pipe from freezing through.

    The big pump makes more pressure, and can force the water through a thinner channel.  The friction of the water against the pipe actually warms up the water.

    What sort of low temperatures is this watering system exposed to?

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
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  • draines
    draines Registered Users Posts: 17 ✭
    #5
    He says -20F. It's in southern Colorado (Alamosa area). The pump he currently uses an Everflo (http://shop.pressurewasherproducts.com/Everflo-EF5500-55-gpm-60-psi-12-Volt-Diaphragm-Pump-EF5500.htm) and he doesn't have any anti-freeze features on it.
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  • Aguarancher
    Aguarancher Solar Expert Posts: 315 ✭✭✭
    #6
    If he is running the 12V pump you listed, he wouldn’t need an inverter. If he installed solar panels the most he would need is a charge controller. Which ever pump you decide on, if he is using it 24/7, make sure it is brushless..
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  • draines
    draines Registered Users Posts: 17 ✭
    #7
    Yeah, he currently uses it off 12v batteries that he delivers to each pump daily. Rotates it with freshly charged battery. Then takes the "used" battery home and puts it on a charger until the next morning...then repeats the cycle.
    It's so hard to know how much trust I can put into their pump curves. The one he uses has max 17Amp but pump curve at 0 psi would be around 7-8Amps. Huge difference when trying to design the proper system/bank.
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  • efmkxb
    efmkxb Registered Users Posts: 1 ✭
    #8
    We have 12V centrifical pumps that work at 3 gpm and draw 5 to 15 watts. These are solar pumps for outdoor so pretty sure they will work in freezing temperatures. They are rated for 32F up to 200F and do work well even with a head. We tested at 10ft of head and teh 15 watt pumped as spec'ed. You can see the video at greatbreweh.com. We alsosell them to the drewing industry with a variable controller and they work flawlessly.
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