Summary

An enclosure for a battery-powered device that can be attached to a water reservoir (e.g. a bucket). Attach a float switch, a lithium ion battery, a USB charging circuit and e.g. an ESP8266 microprocessor with Wifi to build a small device that notifies you when the water reservoir runs low.

Instructions

You will need a few things to assemble the water level sensor:

These parts cost about $1 each.

A 18650 lithium ion battery. Available e.g. at Amazon. Don't take the cheapest ones.
A programmable microprocessor with Wifi, e.g. the Adafruit ESP8266 Huzzah or a generic NodeMCU board. Maximum size about 25mm x 50mm.

These parts cost about 10$ each.

Probably you'll need a soldering iron and some cables.

See my github repository for code and further information.

Attention: Be careful with Lithium batteries. I have not tested this enclosure for safety. It is certainly not entirely weather-proof. Safety will depend on your choice of batteries, battery protection circuits, charging circuits etc. I do not take any responsibility if you're batteries suddenly catch fire.

If you want to make changes to the model, download
originals.zip which contains the JSCAD source files.

Battery-powered Water Level Sensor