DC Water Pump / Battery / Solar solution for a strawberry tube

**bcroe** · 03-11-2021, 01:49 PM

Originally posted by AndyInNYC

The timer will obviously draw whatever power it draws; the pump will be on for 20 minutes, 12 times a day (240 minutes or 4 hours). In my non-electric unstanding mind, I *think* this means that I will draw (without factoring in the timer's draw) 18.4 amps each day - 4.6 watts * 4 hours.

Q1: Is my calc correct on the pump - 12v @ 300 milli amp is 4.6 watts while it runs correct?
Q2: Forgetting about the timer, am I using 18.4 amps per day (is that even the right nomenclature)?

Nice project, start by getting your units sorted out, or calculations are worthless.
12V X 0.3A = 3.6W
0.3A x 1/3 hour X 12 times per day = 1.2 Amp Hour per day
add timer A X 24 hours = ... Amp Hour per day
Not a lot, size your battery amp hours to run several days (or as many cloudy
days as you expect). Some would rather do it in watts, A multiplied by 12V.

good luck, Bruce Roe

**Mike90250** · 03-11-2021, 02:56 PM

Bilge pumps for boats might be a good source for a reliable pump, and they have a float switch in case the water level drops.

**peakbagger** · 03-11-2021, 06:52 PM

For what its worth I used a couple of Rule brand bilge pumps for my garden watering system last summer. I have an old shallow well and a plastic tote tank up on a stack of wood. Total elevation head was border line for one pump as the water level dropped over the summer so I went with one pump in the base of the well pumping up to plastic barrel sitting on the ground and a second pump in the barrel pumping up to the tank. I use plastic bilge pump float switches mounted upside down to stop the pumps if the tanks are full. I have two 12 volt ancient Siemens panels that are probably good for 60 watts with one supplying each pump.

The pumping system worked well but I had poor success with various soaker hoses. I ended up with an old fashioned whirylbird type sprinkler that probably has a 6' radius when fed from the tote. I did get a Rule brand higher head inline submersible at one point and that lasted 3 days. So I would stick with the run of the mill 12 volt Rule sump pumps.that run around 50 bucks. The have a coarse strainer but are clear water pumps so make sure there are no solids in the sump.

**AndyInNYC** · 03-12-2021, 11:26 AM

Thanks for the replies, but I'm not there yet on info.

A bilge pump is overkill - I'm only trying to trickle water through an 8-12" vertical PVC pipe.

The DC pump I'm looking at is something like this one https://www.alibaba.com/product-deta...4e20a9f7Sgra1F

The timer is something like this one: https://smile.amazon.com/JVR-Program...NsaWNrPXRydWU=

So, given the math I've been corrected on above (3.6 was a typo), it appears that any deep cycle battery should work.

Q: Am I correct that a 35 Amp hour battery like this one https://www.amazon.com/Sealed-Lead-A...40516926&psc=1 would run the pump (assuming the timer was 0 Ah) for 29 days (theoretical efficiency)? Or am I still getting my electrical math confused?

This pump will only run in the Spring - Fall.

Q What size panel (watts) do I need in order to keep the battery charged (given the real life assumption of timer usage + pump usage)? If I can go really small, I can just mount it off the deck - 50 watts or more is more problematic. I'm still confused about the sizing. Seems like 1.2 amps per day total need s/b.

Q: If I need to run the panel a longer distance, what cheap cabling can I use from the panel (side of house) to the controller (sitting on deck next to battery)?

Thanks for the input; nice having people who know the answers sharing their knowledge.

Andrew

**SunEagle** · 03-12-2021, 04:11 PM

Originally posted by AndyInNYC

Thanks for the replies, but I'm not there yet on info.

A bilge pump is overkill - I'm only trying to trickle water through an 8-12" vertical PVC pipe.

The DC pump I'm looking at is something like this one https://www.alibaba.com/product-deta...4e20a9f7Sgra1F

The timer is something like this one: https://smile.amazon.com/JVR-Program...NsaWNrPXRydWU=

So, given the math I've been corrected on above (3.6 was a typo), it appears that any deep cycle battery should work.

Q: Am I correct that a 35 Amp hour battery like this one https://www.amazon.com/Sealed-Lead-A...40516926&psc=1 would run the pump (assuming the timer was 0 Ah) for 29 days (theoretical efficiency)? Or am I still getting my electrical math confused?

This pump will only run in the Spring - Fall.

Q What size panel (watts) do I need in order to keep the battery charged (given the real life assumption of timer usage + pump usage)? If I can go really small, I can just mount it off the deck - 50 watts or more is more problematic. I'm still confused about the sizing. Seems like 1.2 amps per day total need s/b.

Q: If I need to run the panel a longer distance, what cheap cabling can I use from the panel (side of house) to the controller (sitting on deck next to battery)?

Thanks for the input; nice having people who know the answers sharing their knowledge.

Andrew

That 35Ah battery really needs somewhere between 3 and 5 charging amps which is really a 100 watt panel or maybe 80 watt depending on its Imp rating and your location to get really good sunlight during the months you will be running a pump.

**AndyInNYC** · 03-12-2021, 05:16 PM

SunEagle,

Thanks - so either charge from my CTEK US 3300 or get a 150 Watt or so panel?

Any idea on wired connection over 25-40 feet?

Andrew

**SunEagle** · 03-13-2021, 09:20 AM

Originally posted by AndyInNYC

SunEagle,

Thanks - so either charge from my CTEK US 3300 or get a 150 Watt or so panel?

Any idea on wired connection over 25-40 feet?

Andrew

The voltage drop can be calculated based on the wire size, distance and current draw. Remember you want to keep the VD below 2% or you can cause damage to the equipment.

**AndyInNYC** · 03-13-2021, 06:07 PM

SunEagle - you're treating me as if I'm intelligent on these matters; I'm not. If I have a panel and the controller 40 feet away (and the battery 12 inchese from there), what type of 40' cabling would I buy (or a link as an example) to get power from panel to controller?

If the controller is attached to the panel, do I need a different kind of wire to go 40' to the battery?

Thank you.

Andrew

**SunEagle** · 03-13-2021, 10:24 PM

Originally posted by AndyInNYC

SunEagle - you're treating me as if I'm intelligent on these matters; I'm not. If I have a panel and the controller 40 feet away (and the battery 12 inchese from there), what type of 40' cabling would I buy (or a link as an example) to get power from panel to controller?

If the controller is attached to the panel, do I need a different kind of wire to go 40' to the battery?

Thank you.

Andrew

Well IMO you would run the higher voltage over the longest distance. So if the battery is 12V and the Vmp of the panel is over 17V then use the longer run between the panel and charge controller.

You need to know the amount of Imp amps that the panel will send to the CC and the Vmp voltage along with the distance. You can use this calculator to determine the voltage drop. By changing the wire AWG size you will get a percent voltage drop value. Try to get a number below 2%.

Right now the calculator has #10AWG wire, 5 amps, 17 volts and 40 feet distance. That calculate to over 2% but those amp and volt numbers are estimate. Try it with the real values and then play with the wire size.

**peakbagger** · 03-14-2021, 02:13 PM

My guess its its heck of lot easier to install a storage tank and then adjust the flow rate to trickle through the tube and then use bilge pump to refill the tank. No battery no controls except for a float type level switch.

**AndyInNYC** · 03-14-2021, 03:27 PM

I don't think a storage tank will work - if you look at the layout, there's no way I'm going to get a storage tank hanging off the deck above the tube in a wife-friendly manner.

The pump arrived today. Per the specs, it's 12V 36w 300cm head max 240 L/H. My only concern is that it might be too powerful. I'll buy a long section of tubing and see how much appears at the outlet.

Is my calculation jn an earlier post correct that my 35Ah deep cycle battery would last more than 20 days using 1.2 Ah/day? Or is there some other 'battery conversion math' that I'm totally missing?

The pump is roughly an inch cubed in size - if this works, I may need to set up a few more strawberry towers <g>.

pump.jpeg

Andrew

**bcroe** · 03-14-2021, 03:42 PM

Originally posted by AndyInNYC

The pump arrived today. Per the specs, it's 12V 36w 300cm head max 240 L/H. My only concern is that it might be too powerful. I'll buy a long section of tubing and see how much appears at the outlet.

Is my calculation jn an earlier post correct that my 35Ah deep cycle battery would last more than 20 days using 1.2 Ah/day? Or is there some other 'battery conversion math' that I'm totally missing? Andrew

Yes get your numbers straight. Before you said the pump used 0.3A (3.6W), now you
say it uses 3A (36W). Bruce Roe

**AndyInNYC** · 03-14-2021, 04:11 PM

3.6 - typing on a Chromebook.

Original Towers.jpeg

These were the original in ground towers when I planted them - they did great until the water timer broke over a 1 week vacation.

So, yes, 3.6 watt. 300 mA * 20 minutes * 12 runs per day = 1.2 Ah/day - will the 35 Ah battery in my link above run for 20 or so days before running out? I'll likely use the trickle charger weekly.

Andrew

DC Water Pump / Battery / Solar solution for a strawberry tube

DC Water Pump / Battery / Solar solution for a strawberry tube

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