Low power soil moisture sensor (battery)?

[Christoph Blank]

Hi there,

I'd like to create a low-power, battery driven soil moisture sensor (I'm already using many battery powered mysensor nodes)
and wonder what would be better:

1. I2C - not sure about the deep sleep consumption here
   https://www.tindie.com/products/miceuz/i2c-soil-moisture-sensor/

2. Analog (Standard Aliexpress Sensor, found a power consumption spec on this page)
   https://www.dfrobot.com/wiki/index.php/Capacitive_Soil_Moisture_Sensor_SKU:SEN0193

Does anyone have experience with these? I'm not sure if they can be easily turned off when sleeping e.g. if I connect them to
a digital out and switch it?
What would you use?

Thanks a lot!
Christoph

[mfalkvidd]

@christoph-blank I use a resistive sensor: https://forum.mysensors.org/topic/2147/office-plant-monitoring
About 10 years battery life on 2xAA.

[pdey]

I'm using miceuz's Chirp I2C sensors here. Found it to be much more reliable and consistent than the cheap analogue sensors, particularly dealing with large outdoor temperature variations. The "rugged" model works a charm.

I'm getting about 12 months off 2x AAA batteries, using some aggressive sleeping. As you've surmised, hook up the power in line to a Digital Out so you're not constantly powering the sensor when your board is asleep. You'll need to wait() about 200ms for the board to wake up after supplying power, and take a few dummy readings each time you wake it for it to stabilise.