IoT Device Pulls Its Weight In Home Brewing

The iSpindel floating in a test solution.

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.

Hydrometer [Source:]

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:]

57 thoughts on “IoT Device Pulls Its Weight In Home Brewing

    1. Hmmm, that would be most interesting to analyse as to its veracity because,
      unless the “calibration procedure” is fully dynamic ie not Static, then it cannot
      account for the dynamic of bubble formation & release both of which are
      surely probabilistic…

      Pray tell how this paradigm can possibly be accommodated please ?

      1. You might find that it’s not perfect, but “good enough” to indicate the process of a brew. Within about 2 gravity points would be handy – I want to tell the difference between a final gravity of 1.012 or a stalled brew at 1.020.

      2. i had a quick look because i was intrigued by this “heeling cylinder” method..

        “The inclination angle changes in relation to the buoyancy and thus directly in relation to the sugar content. There is an angle formed between the center of mass and the center of buoyancy depending on the density of the fluid.”

        i have no clue about brewing, which is likely national treason here in Belgium. (degrees plato wut?)

        he’s referring to this procedure :

        from my limited understanding of the matter, it looks like they compensate with a value interpolated from empirically determined values (inclinations) from tests in solutions ranging from clean water (0 degrees Plato, SG 1.000) to (2.5 degrees Plato, SG 1.010 or 2.5 degrees Brix)

        if this adequately compensates for the effect the CO2 bubbles have on the inclination, i have no idea.

        1. You can achieve a precision of 0.002 SG quite easily, it depends all on your efforts to calibrate. But frankly this is not the first interest, because you are interested in the change over time to monitor the fermentation progress.

      1. Well, someone in the german foum already tested a vibration motor. Unfortunately, it didn’t work. The bubbles stayed. Maybe a bigger motor qould help.

        But the thing is: This device is not for the perfect measurement. It is to surveillance and log the data. As a brewer, you are interested when the yeast stops producing alcohol. So for this purpose, it is reallsy good.

        1. Nice, I’d have to do my own experiments to confirm. Another option might be ultrasonic vibrations. It would be quieter and might use less energy but might disturb the rest of the brew.

          I know putting fizzy drinks in my ultrasonic cleaner gets the fizz out. But it’s working so probably no need to guild the lily.

    1. A refractometer let’s you open your fermentation container serveral times. And you always have to take a sample. This is a infection risk. Also, the cheap analog refratometers from China are not accurate. Better use the iSpindel and and while brewing and at the end, a hydrometer.

  1. Maybe I’m overthinking it a bit, but it seems like if you could incorporate some sort of inductive (wireless) charging for the battery, you could make the whole thing into a completely sealed unit that doesn’t need to be regularly opened. Just put it on a charging mat between batches.

    1. Great idea in principle but I don’t think it is practical. Main reason is that yeast and other crud will get lodged in the thread of the cap, and if you leave it there will be a source for future infection. Far safer to completely dissasemble and soak in a sanitiser between uses.

      1. For some reason, most of the people I encountered in homebrewing (at least when I started) including the guy at the home brewing supply shop called it a “hygrometer”. So did I, until I learned that was not the correct term! I wonder if it is one of those errors that simply caught on and spread for some reason.

  2. Nice. But how about the wireless communication through my stainless fermentation vessle? That won’t work. Also the amount of hops that will stick to the tube will affect the angle, which is different for different beers.
    So it would not measure perfectly but maybe good enough for a hobby. In larger stainless tanks it would be better to take a sample.

    1. There are some people in the German forum, who installed a simple repeater by the vessel. And it worked. Maybe there are even better solutions.

      And yes, you are right, but for homebrewers, it is most insteresting at what time the yeast stop producing alcohol. So you don’t need the exact number, the curve is enough. And before botteling, you should measure once with a more precise instrument :)

  3. Why is it that there is an undue fascination with beer making, and that every other article has to be about some device to control the temperature and timing of it? This has to be the 100th such article I’ve seen here. Why not a concrete setting machine? Why not a watering timer/humidity controller for a garden? Why not a device to properly measure or time ANYTHING other than beer making? Seriously, enough with the beer making.

    1. Really? 100?

      If I put BEER in the search, I get around 10 articles about brewing in the past 5 years.

      And the thing is, a lot of people like beer, and when you start making it by yourself, you realize how easy it is to automate the process.

  4. Brilliant! I’ve had many conversations with people over the years about how best to do this. Most of the ideas revolve around reading a hydrometer level, from ultrasound distance-measurement to using a mouse optical sensor to a coil of wire inside a magnet measuring changes in inductance as things floats up and down. All the ideas I’ve seen have problems with reliability, sensitivity, contamination or just the simple ability to keep everything sterile. This is really clever work.

  5. Hi, How do you deal with different types of beer? For example German Wheat Beer produce a huge “foam” during fermentation (crop yeast). This can hold your tube providing a wrong measurement for long days. Thanks.

    1. As fermentation finishes up, the krausen dissipates back into the wort, and the sensor will settle. Since we’re looking for the final gravity, it shouldn’t be too big a deal. The other part to this, the temperature sensor, should still be accurate enough, and that’s more of a critical* factor during active fermentation than what the gravity is at that point.

      *Temperature control being one of the major differences between a “pretty good” beer and “nectar of the gods” beer. Too-warm fermentations can lead to off-flavors as the yeast is stressed.

      And who returns a sample, or *gasp!* throws it out? That always goes through a secondary sampling. Mmmmmm.

      Finish your beer, there are sober kids in India.

      1. Here is the point , since the iSpindel is floating in the center of yeast activity it was surprising how much it’s measured temperature derives from kettle outside. So the next step is to control fermentation temperature by the temperature measurement from the iSpindel. That’s already working surprisingly good and being developed called iRelay.

  6. My dad is a wine maker, I’ve been working for him, and I know people who analyse samples with much more complicated devices than a simple hydrometer which is a very important tool in winery and brewery, don’t get me wrong. But getting a consistent production over the years involves tracking much more stuff than density, however for the home gamer, doesn’t matter.
    However… Not returning a sample, sanitizing the stuff… This is a freaking waste of time and money in WINERY (don’t know for beer). Acidity is so strong that it will destroy most of the bacteria that could be in the solution. That’s also why sulfur (sulfur dioxide to be accurate) is used in the making of wine, it kills most of the bad bacteria that could be introduce with the fruits. Because the main source of contamination is here! SO2 is bubbled through and dissolved in water, then this water is introduced in the grappe juice with the enzymes needed for fermentation (they ARE bacteria). Tank cleaning is done with tap water and usually you can’t remove everything from the wall (thick crystals form on the walls).

    1. The inclination measurement works surprisingly fine. Only during the first 10 hours after yeast pitching the calculated SG is a bit too high but during the rest of the fermentation the SG is within 2 SG point of the actual SG. I have compared the iSpindel with my CO2 production sensor using my fermentation SW Tcontrol during a few fermentation’s and both SG curves match well.

  7. Fermentation generates heat and is one of the reasons why we need to control the temperature in our fermentation chambers (mine is a fridge with my own controller).

    The temperature inside the chamber (when the fridge is not active) will be influenced by external ambient temperature and the beer. If we find the relationship between ambient and chamber temperatures (ie. test without a beer in there) then the remaining factor is temperature change due to fermentation.

    Once temperature change in the chamber approaches the relationship between it and ambient then fermentation is complete.

    I have been data logging my fermentations and see that my fridge kicks in more at the start of fermentation, which makes sense.

    Has anybody actually tried to use this relationship before?

  8. O.M.F.G! :-)

    I started developing this idea at LEAST 7 years ago and couldn’t figure out how to measure the SG. I researched patents on all kinds of devices and it **NEVER** occurred to me that the angle would work! Friggin’ GENIUS!!! I have Wemos chips right here and a Double IPA I just tapped… I will build this tonight!!!

    THANK YOU!!!!

  9. I’m pretty sure this is the most information I’ve found out about Moonshine in one place! Definitely some interesting facts about things like how Nascar was born? That’s a new one for me. I know that there are dozens of sponsors and A TON of beer influencers going on since one of my family members got to work for a well-known beer company. She got the chance to go around to events as a sponsor and give out free stuff.

    It’s amazing at what it takes to brew this stuff. And, the fact that people have worked on it for so long! Talk about trial and error.

    Valerie R…

  10. If ‘all you want to know is when fermentation has stopped’, put your ear to the bucket, or if you must. develop a wireless microphone and convert the unmistakeable sound of fizzing to a DC level or some numbers.

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