Negative ABV reading from Tilt?

[Stack]

Sorry if this has been covered elsewhere, I couldn't find anything...

I'm brewing my second or third batch with the Tilt integration but for some reason, the graph on the Fermentation tab is showing a negative ABV value:

The OG on this particular batch came out much lower than expected (1.066 actual, 1.080 expected) and I'm not able to drop the temperature all the way down to the target 66°F. I'm assuming these are contributing factors. Is there a way I can correct this? The current gravity is at 1.056 so the ABV should not be a negative number, right?

 

[Yooper]

It's showing attenuation at -1350(?) %, so something may be wrong with your original entry. Can you take a look and see if it's simply a data entry error at the beginning?

 

[Yooper]

Oh, yeah, and 550 degrees fahrenheit- so maybe you mean something a bit less.

 

[Stack]

It's showing attenuation at -1350(?) %, so something may be wrong with your original entry. Can you take a look and see if it's simply a data entry error at the beginning?

Thanks for the quick reply Yooper!

I went back and looked at the recipe and the only thing that I noticed was under the Yeast section, the Custom Attenuation field was set at 0%. I don't know if this is normal, I don't recall ever editing that field but regardless, I changed it to 75%. I also changed the Fermentation Temp field to 70°F from 66°F. I saved the recipe, went back to my Brew Session and clicked the Rebuild Brew button under the Edit tab. I waited for the next Tilt update but again, the ABV (and Attenuation as you noted) are still negative numbers. I checked the Recipe View tab to confirm that the edits to the Yeast section went thru, and they did.

One thing I did not change is the amount of yeast to pitch. Based on the expected values on the original recipe, I was going to pitch two packets because of the expected 1.080 OG; Because the actual OG came out to 1.066 I only pitched one packet.

Other than that, everything else in the recipe looks fine, nothing sticks out. Is there somewhere else I should look?

 

[Stack]

Oh, yeah, and 550 degrees fahrenheit- so maybe you mean something a bit less.

Disregard below! I deleted that first data point from the Tilt and that fixed the attenuation reading. ABV is still negative though.

- - -

Where are you seeing that?? The very first data point sent from the Tilt showed a temp of 999°F and OG of 1.040. No idea where those values came from but the next data point, which happened a few hours later, was more accurate. Come to think of it, the data point after that took 4 hours to show up, but it's been consistent since then.

 

[Yooper]

Disregard below! I deleted that first data point from the Tilt and that fixed the attenuation reading. ABV is still negative though.

Hmmmm. It's got to be in the SG readings then, or somehow related to the attenuation. Are all the SG readings looking correct?

 

[Yooper]

Hmmmm. It's got to be in the SG readings then, or somehow related to the attenuation. Are all the SG readings looking correct?

The reason I ask is that the SG readings on the graph start very low (below the chart view) and go up higher than your actual OG:

Please ignore my amateurish red circles and lines- but those are what I marked to show you what I mean.

 

[Stack]

I think simply deleting that first erroneous Tilt reading fixed the issue. As soon as I deleted it, the Attenuation reading was correct. And it wasn't immediate, but the ABV reading eventually corrected after deleting that data point, probably within a minute or two. That seems to fall in line with your suggestion about the SG since the very first reading showed 1.040, and the temperature was 999°F as mentioned earlier. Although looking at the screenshot again, OG/SG may have been 1.004, not 1.040. That's probably more accurate.

Either way, it's working now. Thanks for all your help!

 

[Yooper]

I think simply deleting that first erroneous Tilt reading fixed the issue. As soon as I deleted it, the Attenuation reading was correct. And it wasn't immediate, but the ABV reading eventually corrected after deleting that data point, probably within a minute or two. That seems to fall in line with your suggestion about the SG since the very first reading showed 1.040, and the temperature was 999°F as mentioned earlier. Although looking at the screenshot again, OG/SG may have been 1.004, not 1.040. That's probably more accurate.

Either way, it's working now. Thanks for all your help!

I did smile at your thanks- I appreciate it.
I'm glad it is sorted now, and just let us know if there is any thing else that comes up in the future.
Cheers!

 

[ttsalo]

I don't know if this is related, but I have noticed that (sometimes?) when the Fermentation tab reloads the measurement data, the curves get updated, as do the Target, Attenuation, Calories and Readings values, but the Temp, Gravity, ABV and Days values are stuck until I force a full refresh of the page from the browser.

 

[Stack]

I don't know if this is related, but I have noticed that (sometimes?) when the Fermentation tab reloads the measurement data, the curves get updated, as do the Target, Attenuation, Calories and Readings values, but the Temp, Gravity, ABV and Days values are stuck until I force a full refresh of the page from the browser.

Yeah, I noticed that too. I’ve conditioned myself to do as you suggest, full refresh the page to get accurate readings. My issue was definitely the first reading from the Tilt. The temp. was 999F and gravity was 20 points lower than actual gravity. Deleting that data point from the graph fixed both within a couple minutes.