Hi!
I just finished to set my brewpi and I’m testing it fermenting some cider.
I think that it’s working quite well, but I see some oscillation on the beer and fridge temp that is quite weird, for example a big drop right after it was applied some cool.
I have a small chest freezer, with a “reptil heat cable” around the walls of it.
Any ideas? I leave you here a screenshot of the graph and the configuration I’m using right now. THanks in advance!!
Min Temperature:
1,0
Max Temperature:
30,0
PID: Kp:
10,0
PID: Ki:
0,051
PID: Kd:
2,0
PID: maximum:
10,0
Integrator: Max temp error C:
0,5
Temperature idle range top:
1,0
Temperature idle range bottom:
-1,0
Heating target upper bound:
0,301
Heating target lower bound:
-0,199
Cooling target upper bound:
0,199
Cooling target lower bound:
-0,301
Maximum time in seconds for heating overshoot estimator:
600
Maximum time in seconds for cooling overshoot estimator:
1200
Beer fast filter delay time:
3
Beer slow filter delay time:
4
Beer slope filter delay time:
4
Fridge fast filter delay time:
1
Fridge slow filter delay time:
4
Fridge slope filter delay time:
3
Thank you so much! I tried to optimize KP as suggested testing different numbers, and I can see less overshoot (right now with KP 2,5 / KI 0 / KD 0). The problem is that the beer temp still changes too much, mostly as soon as the cooling start , isn’t? Any further suggestions to try to keep it more steady? Thanks for the amazing job!
Indeed! Yes, actually since is just a test batch I’m fermenting just 4l on a glass carboy. Next time I’ll use my SS Bucket with the thermowell on the lid.
Just curious, the big drops after the cooling part do you think is also related with the temp probe attached to the side?
Yes, the advice about moving the fridge sensor still stands.
You can set Ki back for steady state errors, but make sure the proportional part remains dominant unless your are at steady state. Too much/fast integral action can also cause overshoot.
