Brewing beer or making wine at home isn’t complicated but it does require an attention to detail and a willingness to measure and sanitize things multiple times, particularly when tracking the progress of fermentation. This job has gotten easier thanks to the iSpindel project; an ESP8266 based IoT device intended as a DIY alternative to a costly commercial solution.

Tracking fermentation normally involves a simple yet critical piece of equipment called a hydrometer (shown left), which measures the specific gravity or relative density of a liquid. A hydrometer is used by winemakers and brewers to determine how much sugar remains in a solution, therefore indicating the progress of the fermentation process. Using a hydrometer involves first sanitizing all equipment. Then a sample is taken from the fermenting liquid, put into a tall receptacle, the hydrometer inserted and the result recorded. Then the sample is returned and everything is cleaned. [Editor (and brewer)’s note: The sample is not returned. It’s got all manner of bacteria on/in it. Throw those 20 ml away!] This process is repeated multiple times, sometimes daily. Every time the batch is opened also increases the risk of contamination.

To replace this process, the iSpindel measures specific gravity and temperature regularly and hands-free. The device consists of a plastic tube, a 3D printed raft, an IMU for measuring the angle at which the tube floats, a temperature sensor, a rechargeable battery, and a Wemos D1 mini (ESP8266EX based) microcontroller. The inclination angle of the floating device changes in relation to the device’s buoyancy, and therefore in relation to the sugar content of the fermenting liquid.

This is a clever DIY solution that hits all the right notes and takes advantage of all the right elements. The plastic tube is easily sealed and easy to keep clean. The device itself has no effect on the fermenting process, the battery is more than sufficient to monitor fermentation of a batch from start to finish, the sensors give readings every bit as accurate as a properly used manual hydrometer, and the wireless capabilities are used to transmit data from a sealed environment.

Compare this device to this DIY sensor suite for wine monitoring from 2010, which was originally envisioned as a self-contained floating probe but ended up a two-part device. It’s amazing what’s available for hobbyist use today compared to even just a few short years ago.

Thanks for [janniz] for the tip!

[Image source for hydrometer: grapestompers.com]