That is correct. The two devices are calibrated separately. The pill needs to be calibrated when the pill is in access point mode. As mentioned above it's highly unlikely you need to calibrate the pill so I really do not think this is necessary but if you do it's in the AP mode. The pill only has a single point calibration method that takes into account an offset. Once this calibration has been done the pill will send the new "calibrated" number in the bluetooth beacons.
The RAPT fermentaiton chamber and RAPT temp controller will grab this beacon and simply relay this to the web.
The reason that we do not make the calibration on the RAPT fermentation chamber or RAPT temp controller is that you would end up with a double calibration event with one figure essentially putting out the other figure. Also one pill can also be paired with multiple other RAPT devices so this would also create other undesirable results. As a result you have to calibrate each product separately.
I would not bother taking the power dissipation of the electronics in the pill into account. Definitely the pill is warmer once it's just taken off the charge and also once it's immediately thrown into the fermenter. With that said after the pill goes into the fermenter for some hours it will go into "low power mode" and this really creates no significant heat at all.
If you are seeing hotter pill temp than the fridge air temp it is always always caused by the NTC probe on the chamber not being calibrated or alternatively due to head of the fermentation process. I would wait til fermentation slows down a lot and if you see the two numbers get closer then it's more likely that it's just active fermentation making the wort warmer.
If you get to the end of the fermentation process and the pill and chamber still has a different temp that is not getting closer together then I would say you need to calibrate the NTC probe in the chamber or temp controller.
Thanks for the reply. I really appreciate the help sorting this out.
I understand all you are saying so I'll explain it the way I see it:
- My chamber will not maintain the temperature I set when using the Pill as the temperature source.
- When I set the temperature to 20degC I expect the chamber to adjust it's temperature (heat/cool as required) to keep the internal sensor of the Pill at 20degC. Nothing else should matter.
- My chamber mistakenly keeps the temperature 2 degC higher at 22degC. I have physically watched the chamber heat and cool at the wrong trigger points to maintain this error.
My Pill is accurate (measured).
My chamber runs accurately when run on the NTC sensor (measured and recalibrated)
This 2degC offset happens over an entire 2 week ferment profile. (currently cold crashed set to -2degC and maintaining 0degC).
All of the suggestions so far will only effect the rate at which the temperature achieves it's set equilibrium - not the final temperature which is where I have the problem.
I strongly believe there is a mismatch in the data value given by the Pill to what the chamber processes and acts upon.
Not sure what side the error is on and doesn't mater to me. I was hoping a simple offset option could fix it. (I'm sorry I referred to it as calibrating the Pill to the chamber)
At the end of the day I can create a profile that is 2 degC colder for all steps or run an external NTC in a thermowell but being an experienced design engineer and brewer myself I find work-arounds a bit annoying when things are close to being a great product.