To use a more accurate formula, create a synthetic variable with the following content.
og=1.053
(76.08 * (og- insert your gravity variable ) / (1.775-og)) * (insert your gravity variable / 0.794)
Change og=1.053 to be the original gravity of your beer. And for “insert your gravity variable” then replace with the “gravity” variable from your iSpindel device.
You can create a ‘value table’ and this will list all the Gravity readings so you can easily find the first and last, but you can do this on a graph too. Synthetic variables can onlu use add, subtract, multiply and divide. Bummer.
Indeed these types of synthetic variables are only available in our paid tier. Nonetheless, I’ve already shared this case with our Product team and this calculation will be supported in the future, I will add a “+1” to this STEM feature request.
Hi, I’ve tried to create this variable on a STEM account but then get “an error has occurred and variable cannot be created”. Was this functionality allowed for all STEM accounts?
Unfortunately, as explain in my previous note these types of data range expressions are only available in Ubidots paid licenses. Nonetheless, I’ve already added a feature request for the product team to consider enable an expression that allows you make this calculation. For the time being, I don’t have an ETA, but as soon as I have an update I will let you know.
Unfortunately, I don’t have any updates yet from the product team on where this expression for calculating the ABV value will be added. Nonetheless, I added a “+1” to this feature request and hope to have new in the coming months.
I’ve got it to work with the formula above ((76.08 * (og- insert your gravity variable ) / (1.775-og)) * (insert your gravity variable / 0.794)).
It’s a pain to have to update the OG value each time you start a new brew off so I thought I could create a new variable called OG, with a widget to enter the value.
My thought was, when I start the brew off I would enter this value (along with a context of brew name) and then the above calculation could use that variable plus the current SG variable to show the current ABV. The formula says it’s correct but it does not return a value.
Can you please send us an image of this synthetic expression you are mentioned? In that way, we can investigate the reason why is not returning any value. Additionally please keep in mind that you can use the context of a variable to make a calculation only when the context is a numerical value.
Hi @isalogi
For some reason I’m not able to upload screen shots…
I am using a synthetic expression to calculate the current alcohol level in my fermenting beer, using two variables: gravity - This comes from my iSpindel device every 15 minutes OG - this one is set at the beginning of each brewing session, (this is the first gravity reading when I start my brew off), I enter this via a manual entry widget, writing to the OG variable I created in my iSpindel Device.
Both gravity and OG are numerical values in the range 1.000 to 1.200
The formula is:
(76.08*( OG - gravity )/(1.775- OG ))*( gravity /0.794)
When I use this in the synthetic expression to show the current alcohol level the formula validates but I get no values.
If I substitute OG for it’s numerical value (eg, 1.066), then I get a calculated value (eg 5.05%)
Thank you for your response. Sorry to hear you are unable to upload images. Based on your explanation as the synthetic expression involves more than one variable is necessary that all variables have the same timestamp otherwise you need to wrap up the expression with the fill_missing() function, which is not supported in the free version. A way to achieve your goal under the STEM account is by setting the variables to have the same timestamp.