Water Rat (Water Level Sensor) - NB-IoT
- Design Background
Farmo's Water Rat (patent pending) is the best and easiest to set-up tank and trough water sensor on the market. Just throw it in a trough, or tether it to a tank and get low water level alerts on your phone or PC.
How it works:
The Water Rat looks simple but has some smart technology inside including an accelerometer tilt sensor to detect movement, an NB-IoT chip to send data, and a GPS to report location. When the water level reaches a low point, the Water Rat tilts over and sends an alert. When the water level rises and the Water Rat regains position, another alert is sent to let you know the water is ok again.
Data is sent via NB-IoT which is the long-range low-cost version of 4G for IoT devices. The coverage for NB-IoT is approx 30km more from the tower than the 4G network, so if your mobile phone works on site, NB-IoT devices will work. Additionally, NB-IoT transmit on a lower frequency than cellular mobile so penetration through buildings and cement tanks is better.
Monitoring stock water can be made more efficient by technology and allow much more frequent observations. However, human oversight can never be replaced when animal welfare is at stake.
Installation Instructions [download]
- 9 axis accelerometer
- NB-IoT telstra certified module
- 14,000 mAh Li/SOCl2 non-rechargable battery for long-term use
- 1.8m tether rope included
- Each WaterRat requires a NB-IoT data subscription paid yearly.
Includes farmo dashboard and alerts
- Visualise data and set alerts on your PC, laptop or phone
- Display when water level above or below your trigger point
- Set custom alerts via email (free) or SMS (10c each)
- Send alerts to different people at different times as required
- Stock water troughs
- Water tanks
- Agricultural, Household, Industrial, Smart City, Ag-tech
- Flood detection
Care and maintenance
- Tank or trough should be free of objects that could catch, hold or prevent the Water Rat tilting.
- All Farmo products include a 12 month warranty as standard.
Data sheet [download]
We know from experience that a fixed trough sensor has to be incredibly strong to resist the force of a 1-tonne bull. So for the Water Rat we used a different idea of strength inspired by the Ping Fu quote “Bamboo is flexible, bending with the wind but never breaking, capable of adapting to any circumstance" ie if an object is floating, it has no resistance to the force applied to it. The most an angry bull can do is nudge the Water Rat around with its nose.
Secondly, a fixed sensor requires tools and skills resulting in a permanent or semi-permanent installation. Farms may have more than fifty troughs used in rotation, so that requires a lot of sensors. With Water Rat the idea is that you can just pick up and move the sensor when you move the mob.
Finally for tanks, reaching the bottom and tilting is not ideal so we use the simplest possible soloution in the form of a tether that attaches to the Water Rat and to the side of the tank. The length of the tether determines the depth at which the Water Rat will tilt over and alert. Most farmers set this up for 50% full or empty, but it's up to you.
The Water Rat was not our first attempt to monitor water levels in troughs and we went through a few iterations of fixed-in-place models which we thought at the time were pretty good. During installation one day we received the feedback that the sensor was was ok but a lot of customers would struggle with the lengthy and complex installation, and "it would be great if we could just throw it in the water". Hmphf! Sometimes feedback sucks, but we considered it for a while and had to agree. That's when we started thinking about the Water Rat.
Some photos along the way
The fixed in place model
The first floating pvc pipe version
3D print that was too floaty in the base
Folded alumium keel solved the flotation problem
Lots and lots of field testing
A 3d print of the final shape for more testing...