Solar powered OpenSprinkler

[Brad Breer]

I’m considering getting the OpenSprinkler3.0 DC to control my drip irrigation in the garden. It will need to powered by solar so after much Googling I’ve put together a list of hardware I’ll need to power it:

Solar panel
Solar charge controller (that supports the battery type)
Battery

I’m not sure what size battery I will need to properly power the OpenSprinkler3.0 DC. I’ve looked at 12.8v 6Ah LiFePo4 batteries but I don’t know if that’s overkill or not.
I’ve also looked at LiPoly batteries but they seem under powered.

If all that will be powered is the OpenSprinkler3.0 DC which will control 4 or 5 24AC sprinkler valves what is the recommended specs on a battery?

Thanks

[Brad Breer]

After some more googling I’m leaning towards the OS3 Latch even though the valve’s are more expensive. I’ve included a diagram of how I plan to lay it out. Any input/advice is appreciated before I start spending $$. Thanks.

Attachments:

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   solar_irrigation_control.png
   

[Ray]

I am not familiar with batteries used in solar power systems, but I believe 12VDC output is pretty standard and OpenSprinkler DC-powered or Latch both accept 12VDC input (a few volts higher is fine, but should not be more than 15VDC).

Latch is supposed to be more power efficient as the valve stays indefinitely in one state and only draws power when you change its state (from open to close and vice versa). That said, the controller itself also consumes a certain amount of power (around 100mA to 150mA in idle state). As it uses linear regulator to drop 12VDC to internal voltage, this is a power consumption of about 12*0.1 to 12*0.15, which is 1.2 to 1.8 Watt power, which pretty small.

If you go with DC-powered OpenSprinkler, each valve when open consumes about 12VDC * 0.3A = 3.6 Watt power.

[Brad Breer]

So I bought the OpenSprinkler (Latch) to control the three Galcon YLZ 3/4″ sprinkler valves with S1602 DC latching solenoid. The OpenSprinkler will be solar powered by a 20w solar panel charging a 12v LiFePO4 battery. A couple questions.

1. Will the 12v LiFePO4 (12Ah) battery be sufficient (assuming it’s charged) to properly power the 24v valves?

2. For powering the OpenSprinkler I was planning on connecting it to the DC load connections on the solar charge controller but I don’t know how to connect the adapter power connector on the OpenSprinkler to the DC load connections on the solar charge controller. The DC load connections on the solar charge controller are the same wire to screw type like the zone connections on the OpenSprinkler.

Thanks

[Ray]

1. Yes, 12V is ok, in fact, the power adapter we ship with OS Latch is 7.5VDC. The controller has built-in voltage booster to generate the voltage required to open or close latching valves, so it’s insensitive to the input voltage level.
2. OpenSprinkler Latch uses standard DC power adapter plug where the center is positive and side is negative. If you search “male dc adapter” on amazon, you can find plenty of adpaters or cables that can convert between wire screw terminals to DC plug, such as this:
https://www.amazon.com/Xenocam-2-1mm-5-5mm-Camera-Adapter/dp/B01AGQVYQQ
Before using them, make sure you double check the polarity: center positive, side negative.

[Brad Breer]

Thanks Ray.

I’m assuming I don’t need the adapter itself and a DC power pigtail like the following would work:

https://www.amazon.com/gp/product/B00R1XZ09K/

[Ray]

Sure, that works too.

[vinthewrench]

ray: sometimes we don’t get enough solar to charge a battery, do you have any ideas if I want to combine a panel and a ac powered charger to keep the battery charged enough to power the system.. I might use it for Christmas lights in wintertime too. The solar acts as backup for AC or maybe the other way around.. I couldn’t find a charger that also takes external power.

[Ray]

Well this is beyond my knowledge. You may want to ask someone who does solar installation to see what are the options. What I can tell you is that OpenSprinkler Latch draws very little power: at resting state it only needs about 100 to up to 200mA current. So even with 12VDC input voltage, this is about 1 to 2 Watt of power. It draws a bit more when opening or closing valves, but since latching valves only require instantaneous power and does not draw any power when the state doesn’t change, that power is basically negligible.

[Brad Breer]

I just completed my installation of opensprinkler using solar power so I thought I would post this for future reference so others won’t have as steep a learning curve as I did.

My setup:
Opensprinkler: DC latch 3.0
Valves: Galcon sprinkler vale with the S1602 DC latching solenoid
Battery: 12v 12Ah LiFePO4 (4S2P)
Solar charge controller: Huinetul 10A IP68

Points to consider:
The solar controller must match the battery type (lead acid, lithium ion, lifepo4, etc.)
It’s very convenient if the solar controller has a load connection to connect the opensprinkler to.
Make sure to size the enclosure to comfortably fit the solar controller, opensprinkler and battery.
Be sure the solar panel will generate enough power, based on your load, to properly recharge the battery.
The valve solenoids to be controlled by opensprinkler have fairly short wires so:
they will need to be located pretty close to the enclosure or
you’ll need to wire nut in wire to span the distance
Solar panels typically have clamps on the end of the wires to connect to the battery:
These usually need to be cut off to connect it to a solar controller terminals so:
on the solar panel wires mark/note which wire is +/- for future reference in case you need to disconnect and then reconnect.
The opensprinkler power connector is a 2.1mmx5.5mm barrel connector so I found these handy (thanks Ray):
https://www.amazon.com/gp/product/B01AGQVYQQ/
Ensure the opensprinkler can connect to your wifi network:
Distance is critical and having it in an enclosure will inhibit the signal a little so consider ordering the model with an external antenna connector if you think you’ll need it.

Good luck!

[Author]

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