Home Depot Keg / CO2 Volume Sensor?

I saw this for $30 at Home Depot today: http://www.quirky.com/shop/732

I'm assuming it uses load cells which I've previously read wouldn't work for measure a keg's volume as they deteriorate over time if they're under constant load, etc, etc.

So do we think this product doesn't actually work over time or is it something that is possibly reusable for measuring your keg or CO2 tank's remaining volume?

That would be cool if it worked, but is it only calibrated for the weight of an empty propane tank? Is that customizable?

It would indeed be cool if it worked and if it could somehow interact with Raspberry Pints. The problem I would have is space. My kegs are quite literally crammed in the keezer so I get 4 on the floor. I doubt I could fit something like this in it because the base is 9.4".

Now having kegs for a bit and kicking them at inopportune times, I would love to know what I have in there.

The base doesn't look that tall from the pictures I'm seeing, and it is constructed for constant load. If I understand correctly you calibrate it with an empty tank/keg and it just uses that as a tare weight.

Could work, but there might be simpler solutions for less money.


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I just picked up one of these at my local HD. At $30 for a WiFi compatible tank gauge, it's a steal. I plan to use this to actually keep track of my propane tank, but I'm keen to investigate how it works. The base must sport either a strain gauge or a force sensitive resistor of some sort; I favor the latter. I'm also unsure that it would be suited to measuring the fill state of a corny keg, since a full corny would have about 40 lbs of beer in it, while a 20 lb propane tank would be about 20 lb (unless only filled to 75%, as some places will do). With tare weights of about 8.5 and 17 lbs, respectively, empty corny kegs are much lighter than an empty propane tank. So, the unit would not likely report an empty tank with about 10 lbs of beer still in the corny (e.g. 1 1/4 gallons). Still, it's a cheap and cool device. I'll report back once I learn more.

Awesome. Thanks. But I'm like Hello in that my kegs are crammed in my kegerator, so I don't think this would work for me unfortunately.

So, I had a chance to review this further. First off, I must say that this unit is packaged very nicely, and is quite easy to set up. The unit comes in two parts, the "sensor" which is basically a plastic ring with a cord. The cord has a weatherproof 4 conductor 3.5 mm connector that connects into the "hub." The unit comes with 4 Energizer batteries and a small screwdriver to add the batteries. You download an app from either Google Play store or the iTunes store, depending on your mobile device. Once downloaded, you start the app and install a new device into the Wink app. This can be done by selecting the Quirky Refuel, or by scanning the barcode on the box (very slick!). The app then takes you through the process of connecting to your local WiFi. From the app, you select which WiFi network you want to join (the hub detects this), and then you start the link up between the mobile device and the hub. This involves putting your mobile device on the top of the hub, where they link up via a series of screen flashes. Once they connect, an LED on the face of the hub lights up green. A series of 5 leds on the top/side of the unit light up to show the tank level. This is also displayed in the app (e.g. 3/4 full, tank empty, etc). This is a very high quality unit, and I am amazed they sell this for $30. Someone must be losing some $$$.

As for measuring beer levels... this might take some doing. I am pretty certain that the sensor uses strain gauges, esp. given the 4 conductor connectors between the sensor and hub. Also, pressing down on the sensor reveals smooth transitions between the different LED states. The problem is that a standard corny keg is a bit too wide (as is a 1/6 barrel commercial keg). The corny sits nicely in the sensor, but the rubber base on the corny prevents contact with the surface of the sensor that does the measurement. Even so, it might be possible to modify to work without much trouble. The sensor itself is only slightly wider than a ball lock corny keg, so it might be possible to fit two of these into a standard kegerator. Incidentally, the app does allow you to specify a tare weight for an empty tank, so it might be possible to use this unit for beer measurement after all.

BTW, I looked inside the hub and it contains a single round circuit board with what appear to be some small surface mount components (e.g. resistors, capacitors, small ICs), and an Electric Imp 2 daughter card. The EI2 daughtercard is soldered directly onto the round circuit board. I don't know much about the EI2 but, it appears to be an SoC with an integrated WiFi chip. Pretty slick! More info here:

http://electricimp.com/product/

I'm not sure about the OS but it may be possible to hack this to render output more appropriate for the task at hand. In any event, I think this will certainly be useful to keep track of my propane!

Looks like it rests on the "shoulder" of the propane tank, is that correct?
If so, you could make a disc the O.D. of a Corny keg, park that on the device, set an empty Corny on there, record the tare weight, then the full weight.

Do the instructions give a max capacity?

You could probably use a large saucer as the "disc", so as not to add a lot of height to the "stackup".

I'll be watchin'!

Stealthcruiser said:

Looks like it rests on the "shoulder" of the propane tank, is that correct?
If so, you could make a disc the O.D. of a Corny keg, park that on the device, set an empty Corny on there, record the tare weight, then the full weight.

Do the instructions give a max capacity?

You could probably use a large saucer as the "disc", so as not to add a lot of height to the "stackup".

I'll be watchin'!

Click to expand...

I'm not sure what the part is called, but the metal ring on the bottom of the tank that it rests on fits inside the plastic sensor's ring. I don't think it would be very difficult to make it work with either a corny or 1/6 barrel keg. I'm also not sure what the capacity is for the unit, but I would imagine it would be roughly in the range of a full corny (about 50 lb).

Is it true that it only measures in 25% increments?

BeerGrylls said:

Is it true that it only measures in 25% increments?

Click to expand...

Yes, full, 3/4, 1/2, 1/4 and empty from what I can tell. However, it appears to use a standard strain gauge, so if it were possible to hack the software (which seems very likely), then finer measurements should be doable.

There's potential here. Maybe we can get in touch with its creator and see is he'll help. He's got a Facebook account..

it's been a while now, and further thoughts on the device? How is it for measuring gas? Did you make any progress hacking it for kegs?

So I had a chance to take apart the sensor to figure out how it works. It does not use a load cell/strain gauge. Instead, it appears to use three Hall effect sensors with three magnets. The inside ring is under the tension of three springs, and when a heavy item (e.g. a propane tank) is place on this ring, it compresses the springs, causing the magnets to shift position relative to the Hall effect sensors. The result appears to be averaged between the three sensors by a hidden on sensor chip, which is then sent to the unit that houses the Electric Imp. I believe a similar approach is used by propane tank gauges that are often built in to nicer gas grills with a tank gauge. Each Hall effect sensor is connected by three wires, so I imagine that there is an analog signal (e.g. non-latching Hall effect sensor) that is then transmitted to the Electric Imp. However, the on-sensor "chip" that averages all three sensor values is covered in epoxy, so it is not possible to determine if the sensor unit sends analog or digital values to the Imp.

In any event, while the program that runs on the Imp might simply show five "full" levels plus empty, it might be possible to reprogram this to show greater resolution. This approach is likely more stable over time than a load cell, but I would think it would be of lower resolution. Unfortunately, the Electric Imp used in the unit is soldered in and not of the SD card variety. So, you can't repurpose it for other tasks. I have an Electric Imp SD card and April board on order so I can play around with the platform. I'm thinking of trying out my own approach to make a proper load cell based keg sensor.

Wow man. Awesome work. Can't wait to see what you come up with.

I have a JoeTap machine that holds a 2.5 gallon keg. After much R&D, I got it to weigh my kegs properly:

1) 2.5 gallon kegs don't have a tare weight. I simply weighed the keg empty and entered "5.4 lbs" into the Winky app.
2) I filled the keg with my concentrate and water mix.
3) I cut a light, but sturdy piece of cardboard to fit the bottom ring of the keg.
4) Voila, it works!

Because it's measuring the weight of liquid vs. a gas, the accuracy isn't perfect. But considering that the Refuel only provides general incremented feedback (Full, 3/4, 1/2, 1/4 & Empty), it works very well. Simply preventing me from having to open the kegerator to conduct checks, it's well worth it.

findjaime said:

I have a JoeTap machine that holds a 2.5 gallon keg. After much R&D, I got it to weigh my kegs properly:

1) 2.5 gallon kegs don't have a tare weight. I simply weighed the keg empty and entered "5.4 lbs" into the Winky app.
2) I filled the keg with my concentrate and water mix.
3) I cut a light, but sturdy piece of cardboard to fit the bottom ring of the keg.
4) Voila, it works!

Because it's measuring the weight of liquid vs. a gas, the accuracy isn't perfect. But considering that the Refuel only provides general incremented feedback (Full, 3/4, 1/2, 1/4 & Empty), it works very well. Simply preventing me from having to open the kegerator to conduct checks, it's well worth it.

Click to expand...

Very cool! I'd love to see how this is working out.