Rockstar Cooler build


So I am still doing some testing and I keep noticing when I turn off the Pi and restart, the beer temp always starts off in the 100’s then comes down to what the actual temp is. I am not sure why it does this. the fridge temp doesn’t do that. Any Ideas???


As I am testing my fridge and brewpi one thing that I am so confused on is the control algorithms section in the control panel. I have no idea what I need to change if any changes need to be made, How it supposed to work. Is there an in depth section on this and if not can anyone help me to understand it and make sure my system runs correct.

Here is a pic of what my cooling looks like… It seems to over shoot by 5 degrees and then rise just over the set point. What do I need to do to stop it from over shooting so much. If I’m running in beer con. or profile will this fix itself?


It is overshooting because of the minimum cool time. The PID settings are not active in fridge constant mode.
In the next release, the minimum cool time will be configurable and PID+PWM will be used for cooling, so overshoot will be a lot less.

Once you place something in the fridge, you won’t overshoot this much.


Thanks @Elco for the information. I will be testing it with some water in my Fermenter soon in Beer constant. Right now the fermenter is in the fridge but nothing in it lol. It is awesome seeing this thing run. I have to were my fan is always running and I can turn on and off the lights with the switch that came in it. I am planning my next brew day towards the end of Dec. I know that’s a long time but I am still getting some things together and will have the time then.


Re: the sensor reading over 100f;
I had a similar issue on my system, but not sure if it’s helpful. I had a situation where the +5V and the bus line was connected, but the GND was disconnected. There seemed to be some current leak through the 5V to the bus line, making the sensor hot. I have 3 sensors, and this only happened with one of them. When I turned it back on, it was at around 42c which is 107f, around the same.

`PS - awesome build, I love the lights in that fridge…


Hey @James_Young thank you for providing that information. I am going to make up another sensor and check that. It only does it when I turn it off and on. This past time it didn’t do it. I keep checking it. Thanks, I love the fridge I have to say that the size its perfect. It will fit the 14 gal SS brewtech Ferm. just fine. I have the 7 Gal and it nice in there. The fan at the top move the air perfect. the air is pulled from the bottom scoop and then blown out at the top keeping it in constant motion. I have it set up so when I plug the power cord in the fan stays on like it should and I can turn the lights off and on if need as it should. The only thing that is controlled is the compressor. I will post some more pics soon I am still getting things ready on it and doing testing.


@Elco In the Beer-to-Fridge derivative time constant (Td) section below, when it talks about disabling the derivative gain by setting it to zero; is it talking about taking the 1200 in there right now and setting it two zero?? The only thing that I am using my brewpi for right now is just fermenting. Do I need to set all of the sections that talk about setting to Zero? Can you please help.



Actually, that recommendation is outdated. With 0.4.2 I would not recommend completely disabling it.

If you are seeing big temperature swings in your fridge setpoint, check the control algorithm tab to see if it is the derivative that is causing them. (under beer2fridgePid -> d).

Only lower it when this is the case.


@Elco and fellow BrewPi users Please see attached pictures of my graph, and advance settings. I need so major help trying to make sure my settings look good. Elco Here is what I have based on what you asked. Also please don’t worry about the big drop in the middle, that was me resting all my settings. I am just so lost trying to figure out how to set the settings.


Sorry I forgot to add, I am just testing this in water. in Beer const.


What would I be looking for in the control alg? I am not sure. This is what I am seeing:


It might be easier to copy the controller/paste the controller JSON.

Given that you have a lot of mass (beer + conical), I think you can increase beer-to-fridge Kp to at least 10. Because you are running in Farhenheit, set it to 18. Due to a bug, this will result in Kp = 10. This will be fixed in next release. The Kp setting is erroneously scaled by 5/9 when running in Fahrenheit.

Set the beer to fridge max lower, to max 10 degrees F. This will prevent windup.

This is just a quick guess. I’ll start celebrating new years eve now and will have more time to help you in 2016.

Cheers :sparkles: :boom: :beers:


Awesome thank you @Elco! I will do that. lol Well have fun and be safe. Have a few good cold ones for me. I still have all day until I can join you lol.


@Elco I made the changes as stated but I still think its switching to cooling too much. I m just testing water and the fan is constant running, room temp is 73F. The cooler is sealed good as it is brand new and I checked this as well. The temp in cooler jumps up and down so much. I mean my beer temp is staying right on point but I feel that the cooler cycles a lot. Does this look fine? Please see below.


You can change the period to 40 or 60 minutes instead of 20. Then it will cool less often, but longer.


I’m lost. What setting in the controls is that. Sorry I am still trying to get a good understanding of what each one does. I know that there is a decryption with each one but still a little confused.


The cooler PWM period.


Thanks @Elco. So I made the changes. Could you guys please tell me how this looks: (note: This is in beer const. mode, with 5 gal water in SS brewtech cron. )


That looks okay. I would increase both filters of the beer to fridge PID to get a smoother fridge setting.
Also set the dead time (between heating and cooling) higher than the PWM period.


Okay @Elco, lol sorry but not sure which ones are those in the advance settings . So I am going to change (KP) which is 10 right now, (Ti) which is 7200 right now, (Td) which is 1200 right now. Is this what you are wanting me to set higher? also which one is for the dead time? not sure which one this is. Sorry but still trying to figure this thing out. lol