Auber what if question?

[Carp210]

Maybe someone with experience can shed some light on this.
If you did multiple autotunes on the same smoker using different heat sinks (sand, brick, water, rocks) and then used different weights (say 3lb, 12 lb, 22lb) and lastly put these in different locations within the smoker will you get a wide range of PID values?  Does it even matter?  :-\

 

[jbauch357]

I would think yes, it will very much impact the results of the auto-tune PID results.  The Auber is basically seeing how quickly the cabinet heats up and cools down based on how often it is cycling the heating element.  Having larger/smaller amounts of material in the box (as well as what the initial temp of those materials are, how quickly they heat soak, etc) will significantly impact cabinet temps and thus also impact your auto-tune PID results.

After reading through the Auber manual 3-4 times, I decided to change my auto-tune settings to a custom configuration which seemed more appropriate than what came from the auto-tune.  So far I've seen as large as a +/- 10 degree initial swing (if you have a large wood load there isn't much the Auber can do about it once that load catches) from set point as the box settles in, but once it lands on target it never moves.

 

[Carp210]

Josh,
How do you come up with a custom configuration? This is all new to me.  You are right as far as I can tell that once it settles on a target it locks in.

 

[jbauch357]

Look at page 12 here - http://auberins.com/images/Manual/WSD-1200GPH/WSD-1200GPH_v1.0.pdf

I had to read this about 6 times, then print it off and read it another 6 times, then highlight the important parts so I could wrap my brain around it.  Each of the P / I / D settings have a direct impact on how the controller adjusts duty cycle on the element to reach target temperature without overshooting it, then maintain that temperature.  Wik also has his explanation of each in this thread - http://smokinitforums.com/index.php?topic=1285.0

Based on:
- The large swing in auto-tune settings based on what I placed in the smoker
- What the original values were
- What I read and (think I) understand out of the above link

I went with the below settings in my #2.  If I have a large load of wood and minimal protein,  I get as much as a 10 degree overshoot on initial warm up, and it might drop again down to 10 under target, then it'll creep up to set temp and stay there for good.  If I have a big hunk of protein in there warm up takes a bit longer, but I get at most 1-2 degrees of overshoot before settling in.

P - 50
I - 750
D - 150

 

[SuperDave]

I think if someone simulated auto tunes with different loads and noted the PID values, they could enter manual PID values to match the smoke load. 

 

[Carp210]

Thanks Josh,
that is what I was looking for, someone to lead the way.  what would we do without the internet.  Time do get busy, who would have guessed, homework at my age.  Hope I'm not to old to grasp it.

 

[DivotMaker]

I'm usually "all in" when it comes to analysis and experimentation, but I believe you all be getting wrapped up in an exercise of futility.  Here's why... The autotune is designed to "learn" the characteristics of your particular smoker, and should never have to be changed, once it's dialed-in and accurate.  The "meat load" does not matter; if it did, you'd have to change your tuning settings with different smokes.  My 1503CPH unit has undergone one autotune in the last 1 1/2 years, and is dead-on accurate no matter what I'm smoking with it. 

Now, will there be times when the autotune results may have to be "tweaked" a bit?  Sure.  I know some have had to do it, but I'm not sure why.  The bottom line is get it where it holds within a degree or two and don't mess with it anymore.

I also believe the heat sink used during the autotune does make a difference.  You need something that will absorb heat (like meat does), not reflect it (like foil does).  This is why the dry bricks seem to work best.  They'll heat up, and retain heat like meat does, so the box temp will be more stable during the on/off cycles.

 

[es1025]

Me too, one autotune and we are still spot on.

 

[Walt]

Do what cranks your motor. However, Tony is absolutely correct. One good autotune & your DONE!

 

[1stlink]

1 and done here.. working great.