Powering from car battery.

[CraterMountain]

Hi,

I just bought an open sprinkler 3, Latch edition. It will be used to replace my old battery powered controller in my coffee orchard. The controller will be located a long way from any mains power so will be run from batteries. My question is whether I can power it directly from a 12v deep cycle lead acid battery?

The note that came with the controller says no more than 12v, but these batteries can be over 12v when fully charged. Will this damage the unit? Will I need to regulate it down?

Is anyone using a lead/acid battery with the DC or Latch versions of the controller?

Regards
James

[Ray]

I do NOT recommend using the battery unless if you can make sure it has regulated output voltage at 12V or below.

You can use a 7805 linear regulator, a switching regulator like this:
https://www.amazon.com/DZS-Elec-Adjustable-Electronic-Stabilizer/dp/B06XRN7NFQ
or a simpler solution is to use a bunch of diodes in series as a way to drop some voltages. Please make sure that the input voltage MUST be provided through the black power barrel, NEVER provide input voltage through the pin named VIN — the VIN pin is a 5V output pin for powering certain sensors, it’s not for input power.

[CraterMountain]

Thanks Ray, that voltage regulator looks like a good solution. I was also looking at this one https://www.littlebird.com.au/products/pololu-adjustable-9-30v-step-up-step-down-voltage-regulator-s18v20ahv

I’m in Australia, so some amazon options are not available.

I’ll be sure to use the barrel jack.

I assume 2A will be enough? Most of these regulators seem to be limited to 2-3A max.

My latching solenoids need a min of 9v so I’ll need to keep the voltage above that, or does the controller generate a higher voltage when switching them on/off?

[Ray]

Yes 2A is more than sufficient — OpenSprinkler Latch consumes well under 1A so 2A is plenty.

You may want to check if you can find LM2596 modules like the one in the Amazon link. These are widely available and much cheaper than the popolu module. Also they are available on Aliexpress — the shipping can be long during COVID, but the price is unbeatable on Aliexpress.

OpenSprinkler Latch can work with 7.5V input voltage — it has built-in boost converter to generate enough voltage to drive latching valves. So even if input voltage is down to 5V, it can still drive latching solenoids.

[CraterMountain]

Awesome, thanks Ray!

You’ve been very helpful.

[riverracer]

you can get a voltage reg like the Amazon module from Jaycar here in Australia for 8$

https://www.jaycar.com.au/arduino-compatible-dc-voltage-regulator/p/XC4514

[Author]

Posts