@KegLand-com-au can you please document / explain the
Velocity (S.G Points/Day) data series on the RAPT web portal?
When enabled, I see no data points for it and not even a scale. My RAPT Pill is updated to the latest public firmware (20230420_054501_98ef1a1), which has a setting for the velocity. That setting is enabled and set to the second shortest interval (12 hours).
If you need to investigate, the relevant MAC is 78:e3:6d:3d:01:70
We are in the process of finishing off a new method of profiles that uses this so we have been holdings off on releasing a video on this until all the surrounding features are completed. With that said I can give you a bit of an update on this so you know what is in the pipeline.
The reason why this fermentation "velocity" number is so important is because it is one thing that allows us to have much better automation in our fermentation profiles. The "velocity" is how many points per day the beer fermentation moves. The pill hydrometer basically averages the last few hundred points (depending on what your interval is set to, our default will be 12hrs). It then works out the slope of this data and reports this slope as the fermentation "velocity" in units of "SG Points per day". At the moment fermentation profiles have the issue that we assume that a fermentation should jump up to a certain temp such as diacetyl rest or step down to crash chill at a certain number of days into the fermentation process but the reality is we never know when this is from the beginning of the fermentation process so making profiles is quite approximate.
Using the "velocity" number enables us to have profile control that allows us to:
1. Step up temperature to 20C when the fermentation velocity gets to 15points per day.
2. Step up the temperature to 24C diacetyl rest when the fermentation velocity gets to 10points per day.
3. Crash chill when the fermentation velocity gets to 1 point per day or less.
If we do not have this level of control we can't actually make good automation in the profile and often it will be the case that the yeast activity might be too slow by the time we jump up to diacetyl rest for instance and then it's difficult to rouse the yeast back up at this point. Conversely if we have not finished the fermentation process completely then we definitely would not want to crash chill otherwise we will not be able to get the fermentation started again.
So in my opinion this one small feature is one thing that will greatly increase the fermentation efficiencies moving forward so it's a feature that I am quite excited about. Using this feature we can literally never have made a beer before, have no idea how long the fermentation process will take but we can still have an automatic fermentation profile that will manage the process for us.
The only time I would not use the fermentation "velocity" number for a profile is at the beginning of the profile. During the aerobic fermentation period we specifically want to maintain a specific temperature for the first 4 days or so to achieve a specific flavor and aroma profile based on that beer style. So after the 4 day mark this is where the "velocity" will become relevant.
Maybe you can liken this to a workout. If you have ever spoken to a personal trainer they might recommend you to maintain a certain beats per minute to get the optimal results. Beer brewing is really the same and we want to get away from focusing on specific gravity but rather maintaining "SG points per day movement" or "yeast activity".
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