Utter novice seeks complete fountain system help

ard2dabone

New Member
Joined
Nov 11, 2021
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4
Hi all

I'm a complete solar and electrical novice, I have a stand up water fountain/feature that requires a pump and I would like to make it solar.

I have read lots of posts and watched lots of YouTube videos of others with similar questions but I can't find any specific answers to what I'm looking to find out.

I can see that the general consensus is that it's easier and better to set up a pump/controller/battery setup rather than pump direct to solar panel, also for motor protection.

I have seen a 800 l/h 19w pump on ebay. So my questions are:

1. Can I connect a pump of this size without issue direct to a solar controller?

2. If the answer to question one is yes, what specifications do I need to match up? (I see some controllers are rated 10/20/30a)

3. Will a small 6v/12v motorcycle style battery suffice?

4. What size solar panel would I need to search for?

Or if you know of any 'solar/electronics for idiots' style guides for small projects such as this that you can direct me too would also be welcome.
 

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sunshine_eggo

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Hi all

I'm a complete solar and electrical novice, I have a stand up water fountain/feature that requires a pump and I would like to make it solar.

I have read lots of posts and watched lots of YouTube videos of others with similar questions but I can't find any specific answers to what I'm looking to find out.

I can see that the general consensus is that it's easier and better to set up a pump/controller/battery setup rather than pump direct to solar panel, also for motor protection.

Generally, yes, and a small battery can make up for dips in solar production; however, you'll need to protect that battery from completely discharging in poor solar. A solar controller with programmable load ports can do that.

I have seen a 800 l/h 19w pump on ebay. So my questions are:

1. Can I connect a pump of this size without issue direct to a solar controller?


Regular "12V" panels are actually 20-22V open circuit and run 17-19V when producing power. Since it lists 5-12V, I would hesitate to put 17-22V on it. See #2.

2. If the answer to question one is yes, what specifications do I need to match up? (I see some controllers are rated 10/20/30a)

This little guy would take the input from the panel and put out a regulated 12V:


3. Will a small 6v/12v motorcycle style battery suffice?

Yes.

4. What size solar panel would I need to search for?

For 19W, I'd want 50W:

 

ard2dabone

New Member
Joined
Nov 11, 2021
Messages
4
Hi Sunshine_eggo

So I can get a solar controller to programme the maximum voltage to charge the battery and set a minimum voltage to stop at to protect discharging the battery.

Then does the buck controller go between controller and pump to regulate the output to the pump to match the pump specifications?
 

Rednecktek

Solar Addict
Joined
Sep 8, 2021
Messages
792
Hi Sunshine_eggo

So I can get a solar controller to programme the maximum voltage to charge the battery and set a minimum voltage to stop at to protect discharging the battery.
That's exactly what a charge controller does for a living. Unless you're doing something weird you should only need to connect the wires and walk away. Most PWM controllers will have a "Load" terminal that your pump would plug into and are pre-programmed to shut off that circuit before the battery gets too low to charge itself.
Then does the buck controller go between controller and pump to regulate the output to the pump to match the pump specifications?
No need, it's already going to be putting out the 12v to the battery and its load terminals, so just use a 12v pump and call it a day.

2. If the answer to question one is yes, what specifications do I need to match up? (I see some controllers are rated 10/20/30a)
That's going to depend on your solar panels, but a 100w panel is usually about 5a so unless you're going for a LOT of panels there's no need to go large on that*.
3. Will a small 6v/12v motorcycle style battery suffice?
Yes, BUT. A standard motorcycle battery is more like a car starter battery in that it'll push a LOT of amps now, but not for very long. It would be fine for leveling out the voltage but won't last long if it's running all night then charging then running all night then charging. That many cycles will kill it pretty fast.
Now, there are SOME 12v deep cycle motorcycle batteries out there, but they're hard to find. You'd be better off trying to find a small AGM deep cycle battery for something like a UPS replacement or electric toy car (think the old Power Wheels kids cars) or the like. The only downside to using AGM or FLA batteries is that the Ah rating is really half of what it says on the label because lead acids don't like going below 50% draw. So, do the math on how many watts it draws x 24 hours = Watt Hours, Wh / 12v = Amp Hours, Amp Hours X 2 = battery amp hour rating.
Did that make sense? Should I throw in an example math?

Having said that, LiFePo4's are getting to be cost equivalent to their AGM counterparts, especially for the smaller batteries. The benefit is that you can take it down 100% so half the battery capacity and space are needed. The downsides are that you need a LiFe compatible charge controller ( a little more expensive but PWM's aren't that much different) and that they really don't like being frozen. If cold is a concern the AGM's are more forgiving. If not then the LiFe's might be a more sensible option.

Battery capacity gets large FAST so figure in where you're going to stick the battery. Looking at the specs posted it's a 19w pump which is 1.6a per hour. Multiply that by 24 hours and you're looking at 39Ah/day or a little over 460Wh. At a 50% capacity limit for FLA/AGM batteries, that's an 80Ah battery for a single day of running assuming the panel gets enough sun to fully charge that every day. That's a car battery sized battery for 1 day. If you want to compensate for multiple cloudy days, you're looking at doubling or tripling that! :eek: This is where the LiFe battery comes in handy as it'll take up half the space and about 1/4 the weight per comparable battery capacity.

Now, if you stick that on a day/night sensor so it only runs during daylight hours then you only need a little battery to smooth out the power and let most of the running power be provided by the panel directly.

4. What size solar panel would I need to search for?

That's going to depend on your weather and location more than anything. Here in Western WA I see about 2-3% production out of my panels through fall & winter so I need ZOMGHUGE amounts of panels just to not kill my batteries from standby draw (it doesn't work). If you live somewhere that gets all the sunlight all the time, a smaller panel would be fine. Either way, I'd suggest somewhere in the 50-100w range. Bang for the buck is always a factor and if you've got the space you can always over-panel.

Then does the buck controller go between controller and pump to regulate the output to the pump to match the pump specifications?
Nope, the charge controller will be all the converter you need.
 
Last edited:

sunshine_eggo

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Oof... not sure how I missed the reply. Thanks @Rednecktek for picking up the slack. Have a clarification:

That's exactly what a charge controller does for a living. Unless you're doing something weird you should only need to connect the wires and walk away. Most PWM controllers will have a "Load" terminal that your pump would plug into and are pre-programmed to shut off that circuit before the battery gets too low to charge itself.

No need, it's already going to be putting out the 12v to the battery and its load terminals, so just use a 12v pump and call it a day.

The concern was the operating voltage of the pump. The load ports put out battery voltage, which might be as high as 14.8V, so the idea behind the buck was to feed a constant 12V to the pump, so the buck goes between the load ports and pump.
 

Rednecktek

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Messages
792
The concern was the operating voltage of the pump. The load ports put out battery voltage, which might be as high as 14.8V, so the idea behind the buck was to feed a constant 12V to the pump, so the buck goes between the load ports and pump.

Right, but these are often times built to connect straight to a battery so the "voltage" is more operating range (12v nominal) than a hard limit. Since a battery puts out a "12v Nominal" voltage, even being 14v is usually fine, whereas a 20v would be a "Bad Thing" for the motor.

Still easy enough, although I've never seen a "12v" -> 12v buck transformer. Maybe some sort of line conditioner? Seems like overkill though.
 

sunshine_eggo

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Right, but these are often times built to connect straight to a battery so the "voltage" is more operating range (12v nominal) than a hard limit. Since a battery puts out a "12v Nominal" voltage, even being 14v is usually fine, whereas a 20v would be a "Bad Thing" for the motor.

Agreed. It's the "usually" part that trips me up. :)

Still easy enough, although I've never seen a "12v" -> 12v buck transformer. Maybe some sort of line conditioner? Seems like overkill though.

The one I linked above is 8-40VDC in and 12V, 3A out for $15.
 
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