How do I know how much beer is left in my keg?

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KPBrews

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Title says it all. Is there a fuel gauge or something I can buy? (I tried various searches first but "gauge" is clearly pointless when you're not referring to regulators) Obviously venting the gas and popping the lid to take a look-see would work, but is a bad idea for lots of reasons.

I wonder if one of those new gauges they're selling for propane tanks that work by weight would work...

But yeah. Some sort of fuel gauge to let me know how much beer is left in my keg would be super handy. I went to fill growlers for a group of friends coming over this past weekend, and after filling one, the keg kicked unexpectedly. :(

On the bright side, I got to keg my Belgian (which had finished fermenting but I had no keg available) sooner than I thought, but on the downside, I had far less than I planned on for my friends... I'd love to avoid that in the future.

So, is there a tool, or do people just lift the keg (awkward due to my fridge layout), or keep track of pour volume for a rough guess?
 
I have a stick-on white board on the front of my kegerator. I work out the start volume by weighing the keg pre and post fill. I know the volumes of my glasses / growlers and update the volume on the white board after each pour.

There are other nice high tech stuff you can do. Raspberry pints http://raspberrypints.com/ is a really nice system but way beyond what I can be bothered with.
 
Interesting. The SmartStrip seems like a great idea, but I'm not encouraged by the two one star reviews on the site. If it doesn't work, there's little point.

The Ball and Keg, on the other hand, seems pretty simple, and also nice and cheap! The downside is it seems like a bit of a PITA if you force carb, if it has to be added after (or does it?).

The Raspberry Pi product is kinda what I had in mind, but more than a bit overkill in it's current incarnation (who needs a full size monitor for something so simple?), and it doesn't even work automatically! Not that I can tell, at least... it seems like you have to tell it when you draw a pint, and how much you draw (which implies you also need to give it a pretty accurate starting level, which I rarely have). It's pretty cool if you have a massive multi-keg setup, perhaps (4+ lines in a keezer?), but overkill for one or two. (and yet underkill) EDIT: It seems they have a version that uses flow meters to estimate beer volume consumed, but that seems like a silly way to measure, and still requires an accurate starting point value that I wouldn't likely bother with.

I think I might start with the Ball and Keg, unless someone posts something better, and then I'll consider playing around with an Arduino-based system in my spare time. Should be fairly simple and inexpensive, if I can find a decent weight plate that can go in the fridge with the keg, and just run a line outside (just like with a temp probe, should be fine to close the fridge door on without a need to drill) to an Arduino with a simple 2-line LCD with a couple of simple buttons: One to set the empty weight of the keg, and another after filling to start the countdown. Then the display could indicate % remaining.

An Arduino for something this simple would cost about $15 (and I already have several), and a 2-line LCD shield with buttons is about $20, IIRC. (an upgrade to a 4-line LCD wouldn't cost much more) The only real question is how much a compatible weight plate costs. I may need to look into this, because if a weight plate can be had for around $20, this could be a fun, worthwhile project that can be done for under $60.
 
I just tap on the side of the keg and gauge where it starts to sound hollow. Then I get confused when I run out the next day and think the line is frozen or something. Works every time
 
Double_D said:
smart strip was my plan

http://www.kegerator.com/smartstrip-beer-volume-and-temperature-monitor-ss100/SS100.html
Click to expand...

doug293cz said:
The reviews on the smart strip are not very encouraging.

Brew on :mug:
Click to expand...

KPBrews said:
Interesting. The SmartStrip seems like a great idea, but I'm not encouraged by the two one star reviews on the site. If it doesn't work, there's little point.
Click to expand...

I've had four of these sitting next to my kegerator for the past two years and finally tested one last week because I wanted to have a good idea of how much was left. I did the tap/flick test which can easily tell you the difference between a mostly full or mostly empty keg, but turns out it's not so effective when the keg is in the middle half.

So, I stuck one on the keg and sprayed with hot water AND... nothing was discernible from the result. Damn. Tried again, this time using their recommendation of wiping with hot water (wet paper towel with hot water) and this time I could see the inch-and-a-half region of where the level was. It was not a distinct red-white line but more a gradation from white-to-red over the length of about 1.5". It showed the level about at the 2 gallon mark.

It's a definite low-tech way of approximating the level of the beer. I thought it worked fine. I immediately removed it and stuck it back on it's paper backing for future use (probably should have just left it on).

Edit: Granted, I'm using a kegerator so I can easily see the sides of the kegs. A keezer would be pointless - lifting may prove better as a low-tech method.
 
KPBrews said:
[...]The Raspberry Pi product is kinda what I had in mind, but more than a bit overkill in it's current incarnation (who needs a full size monitor for something so simple?), and it doesn't even work automatically! Not that I can tell, at least... it seems like you have to tell it when you draw a pint, and how much you draw (which implies you also need to give it a pretty accurate starting level, which I rarely have). It's pretty cool if you have a massive multi-keg setup, perhaps (4+ lines in a keezer?), but overkill for one or two. (and yet underkill) EDIT: It seems they have a version that uses flow meters to estimate beer volume consumed, but that seems like a silly way to measure, and still requires an accurate starting point value that I wouldn't likely bother with.[...]
Click to expand...

Perhaps I can clear up the evident confusion.

Using RaspberryPints with flow meters, tracking consumed beer and volume remaining is totally automatic from the point you tap a keg - and, yes, indicate initial volume.

I wouldn't call it "estimating" considering every keg that's ever kicked in my 6 faucet keezer in the last year was within one pour +/- an indicated "empty" state.

As for the "full display" thing...well, RaspberryPints was first and foremost a computerized TAP LIST application. And typically, one wants to actually see the tap list. That said, some folks are running displays as small as a cell phone (including, in fact, using old cell phones as displays).

hth

Cheers!
 
stpug said:
I did the tap/flick test which can easily tell you the difference between a mostly full or mostly empty keg, but turns out it's not so effective when the keg is in the middle half.
Click to expand...

May not have been sarcastic enough. I was trying to say its pretty useless even once it gets mostly empty.
 
m00ps said:
I just tap on the side of the keg and gauge where it starts to sound hollow. Then I get confused when I run out the next day and think the line is frozen or something. Works every time
Click to expand...

m00ps said:
May not have been sarcastic enough. I was trying to say its pretty useless even once it gets mostly empty.
Click to expand...

For me, it works as a quick gauge to determine if the keg is basically gone or mostly full - flicking that is, but it's useless for determining any kind of reliable level (lifting is much better but often dislodges/stirs up crap that you pour for the next couple glasses).

Sarcasm or not, it somewhat useful for a quick idea - for me at least :D
 
Thanks, wasn't sure if it was too nerdy, but then I remembered how many engineers and stuff hang out these parts
 
KPBrews said:
Title says it all. Is there a fuel gauge or something I can buy? (I tried various searches first but "gauge" is clearly pointless when you're not referring to regulators) Obviously venting the gas and popping the lid to take a look-see would work, but is a bad idea for lots of reasons.

I wonder if one of those new gauges they're selling for propane tanks that work by weight would work...

But yeah. Some sort of fuel gauge to let me know how much beer is left in my keg would be super handy. I went to fill growlers for a group of friends coming over this past weekend, and after filling one, the keg kicked unexpectedly. :(

On the bright side, I got to keg my Belgian (which had finished fermenting but I had no keg available) sooner than I thought, but on the downside, I had far less than I planned on for my friends... I'd love to avoid that in the future.

So, is there a tool, or do people just lift the keg (awkward due to my fridge layout), or keep track of pour volume for a rough guess?
Click to expand...

The easiest and least expensive way for me is to weigh them. My ball locks weigh about 9 pounds each. A gallon of beer is close to water weight which is 8.34 lbs or about 133 oz. which is equivalent to eleven 12 ounce beers. So your keg (if it's a corny ball lock) when full should weigh around 50lbs. and hold about 55 twelve ounce beers. My math may be off and someone else may wish to chime in and correct me but I believe it's pretty close. Hope this helps.
 
JB_Brewing2 said:
The easiest and least expensive way for me is to weigh them. My ball locks weigh about 9 pounds each. A gallon of beer is close to water weight which is 8.34 lbs or about 133 oz. which is equivalent to eleven 12 ounce beers. So your keg (if it's a corny ball lock) when full should weigh around 50lbs. and hold about 55 twelve ounce beers. My math may be off and someone else may wish to chime in and correct me but I believe it's pretty close. Hope this helps.
Click to expand...

Yes, I've been googling around the consensus seems to be that empty corny kegs weigh somewhere around 8-10 lbs, and beer is slightly heavier than water (I'll call it 8.5), so a full 5 gal corny keg would likely be a little over 50 lbs (10+42.5, +/- several lbs).

I figure a scale that can relatively accurately measure the drop from 60 lbs to 5 lbs would give a reading that is close enough. I don't need to know down to the ounce, after all, but if I can see a readout showing that 5% of the keg (640 oz at 5 gals) is remaining, that's 32 oz left at 5 gals, or ~25 oz remaining at 4 gals (512 oz), so whether my keg started with 4 gallons or 5, knowing that I'm at 5% of the original weight would tell me I have around two, maybe 3 12oz pours left, which seems like a totally adequate level of precision for my use. And now that I look at it, an actual weight remaining (before you hit the empty keg weight), rather than a percentage, would probably be just as useful, if not, more, knowing that 8.5 lbs left in the tank is about a gallon remaining.

Actually, that's probably a couple of pounds off, because co2 has weight as well. Air weight would be negligible at ambient pressure, but when the keg is pressurized, that's probably a pound or two of co2 that would need to be accounted for as well. But all in all, pretty simple math, as long as I can get a reliable way to weigh the tank quickly and easily. And ideally, display the value outside of the fridge.

A quick and dirty solution is probably a cheap bathroom scale sitting under the keg inside the fridge, but the humidity will probably mess with it over time, and I don't know how well the electronics would handle the cold. Or for that matter, the different between occasional step-on use vs. constant strain.

My goal is not NOT have to lift the tank, though (once initially put into the fridge)... I want some way to get an in-place reading. I'll look closer at that Tweeting Kegerator project at SparkFun, too.
 
day_trippr said:
Perhaps I can clear up the evident confusion.

Using RaspberryPints with flow meters, tracking consumed beer and volume remaining is totally automatic from the point you tap a keg - and, yes, indicate initial volume.

I wouldn't call it "estimating" considering every keg that's ever kicked in my 6 faucet keezer in the last year was within one pour +/- an indicated "empty" state.

As for the "full display" thing...well, RaspberryPints was first and foremost a computerized TAP LIST application. And typically, one wants to actually see the tap list. That said, some folks are running displays as small as a cell phone (including, in fact, using old cell phones as displays).

hth

Cheers!
Click to expand...

Yes, it's a killer product for it's intended purpose, I didn't mean to denigrate it. It's just less useful for my specific purposes. :mug:
 
I only drink one pint a day of homebrew so its really easy for me to figure out when its near the end.
 
Other options:
Only keep "real ale" in polypins/cubitainers on tap.
Fit your kegs with sight glasses.
Fit a car reverse parking sensor to the inside of the lid of the keg. When it stops signalling that you are too close, the keg is nearly empty*.
Etch volume markings on the inside of the keg, install an LED light and webcam.

;)


*I can imagine this one working, if you could find a pressure tight feedthrough for the cable.
 
I am at some point going to use a cheap luggage scale to measure my CO2.. but that same scale could also weigh a keg if tare is known...

You'd only have to lift it up 1/4". interesting.. on the CO2 I am going to build a rack to hold it and keep it from falling with foam below in case it does fall off the scale but I was going to leave the scale on... after I run it out and get a tare weight on the tank since it's my first tank and I don't know that value..

Fred
 
http://brew.vision The who thing can be set up on any tablet and thats the only cost. Including the new 50$ amazon one.
Jh1hzux.png
 
KartRacer54 said:
I'm getting ready to get four of these and having my LHBS ordering for others.
Seems to be a great option at affordable price!
https://ballandkeg.com/
Click to expand...

Maybe one of these in a thin tube with a ultrasonic range finder on top connected to an arduino to display the amount left.

If I only had more knowledge and time, the things I could do ;).
 
Hmm.. maybe Inkbird can add pressure transducers to their temp controllers so you can have a display of weight of each keg.. :) that minus tare, times 8 lb/gal*FG could tell you how many oz of beer you have left. There are a lot of different ways to skin this cat.

The float and magnet is interesting, but if you are going to go to $20 worth of trouble, why not just weigh the keg?

I see an interesting "Arduino" project...

Fred

Yup .. this.. and you could add a gas pressure transducer and a temp gauge and a LCD display.. how geeky...

http://www.nerdkits.com/videos/weighscale/
 
UndeadFred said:
Hmm.. maybe Inkbird can add pressure transducers to their temp controllers so you can have a display of weight of each keg.. :) that minus tare, times 8 lb/gal*FG could tell you how many oz of beer you have left. There are a lot of different ways to skin this cat.

The float and magnet is interesting, but if you are going to go to $20 worth of trouble, why not just weigh the keg?

I see an interesting "Arduino" project...

Fred

Yup .. this.. and you could add a gas pressure transducer and a temp gauge and a LCD display.. how geeky...

http://www.nerdkits.com/videos/weighscale/
Click to expand...

Ha! Yes, I watched that video yesterday, doing research on the issue. :)

Closest project I found to what I had in mind is this guy's "KegMon":

http://www.brettsbeta.com/blog/2015/01/kegmon/

He hasn't connected it to an LCD for continuous external readout, that I can tell, but that would be pretty trivial once the main circuit is built. I sent him an email to discuss further, so we'll see if he responds...

Actually, this project looks really sweet, too: http://hackaday.com/2009/12/14/monitor-keg-volume-co2-and-temp/

... unfortunately, the linked page is dead, so I don't know how to find the guy who built it, since no schematics were supplied. So a KegMon variant seems the most likely option.

All that said, I foresee one of two things in my immediate future:

1) A bathroom scale. Literally. In the fridge. I'd have to open the fridge to look, but at least I won't have to lift the keg and guess. (it's kinda precarious in there) Not sure how long a cheap scale would last in those conditions, but it doesn't have to be forever.

2) The Ball and Keg, which is a rough guide but still very useful and a no-brainer.

Either solution is temporary, but either would only cost a mere ~$20, and should last me until I get around to developing a full-blown Arduino-based solution (probably based mostly off of KegMon). I've built some pretty intense Arduino-based things in the past, so I have the necessary electronics building experience, but I it was a group project and others did the bulk of the programming and circuit design. I'm fairly confident I could work it out, though, it's just a question of time and priorities. :tank:
 
poptarts said:
http://brew.vision The who thing can be set up on any tablet and thats the only cost. Including the new 50$ amazon one.
Click to expand...

Looks like a fun project ... I will likely check it out as it matures. But at the moment, it appears to require manual logging of each drink (and presumably you'd need to enter an estimate of how full your keg is as a starting point, then it just subtracts ounces to guess at how much is left), which is not what I'm looking for here. I want a weight-based system so I can see at a glance as the levels drop, and I don't have to log anything as I drink (or guess how much I spill when bottling off the keg, etc.).
 
ah yea if you want auto logging that will never do what you want. It is however simple to use if you mount a tablet on the kegerator. Ive been using it for almost a year.
 
poptarts said:
ah yea if you want auto logging that will never do what you want. It is however simple to use if you mount a tablet on the kegerator. Ive been using it for almost a year.
Click to expand...

An arduino project will never do auto logging? Not sure what you mean there. Obviously pretty much any feature can be added to the Arduino, of course, even web modules that would interface with a tablet or computer, if that's what you want.

Or if you mean the Brew Vision won't log... I'm not sure what you mean, I guess. Temps?
 

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