New Heater Meter with weird issue


 

Andy Morris

New member
Hi All,

I'm new to the forum and looking for help or advice.
Having considered building a BBQ regulator, I came across the heatermeter and think its ideal. I built a version using a Pi Zero and Arduino Nano wihout a display so it would all fit in a case similar to the roto-damper design. Initial tests indoors worked fine and I am in awe of your software and designs. I haven't changed any code and am using as-is.
First cook was today - some short ribs. Initial start was fine and it ran well for the first hour or two until my adaptor plate connecting it my unit to the bottom vent of my kamado clone softened and distorted. I'm reprinting in ABS to see if that works and if not then I'll fabricate a metal one. The bottom of the kanamdo does not get very hot on long slow cooks so I assumed it would be ok. In the meantime, I moved the device to a shelf so I could use it to monitor internal BBQ and meat temperatures and I controlled the vents manually for the remainder of this cook. Having the ability to monitor the temperatures over wifi from indoors (on a damp afternoon) was still a benefit.
Now comes my question/puzzlement. After a couple of hours the HM recorded a rapid temperature drop. After much investigation I identfied that the Probe offset value had changed. I reset this to 0 (from the config page) but from this time on, all the probe offsets kept changing. refereshing the web config page confirmed this - 16, 20 , 32, .... up to 200. Randomly changing different probe offset values at different times but doing it several times a minute. Resetting to zero always showed the right temperature but the offset would change shortly afterwards. I tried different probes, replaced the battery, restarted the device, but nothing would change this behaviour.
I have now completed the cook (ribs are resting) and brought the device back inside to try and find out whats wrong and it's working perfectly with the probe offset settings as stable as a rock ! I'm baffled. Anyone have any ideas?

Andy
 

John Bostwick

TVWBB Wizard
I haven't heard of this issue before. You could see if redoing the software would help. As for what would cause the HM software to change on its own is baffling as it would need to recieve a command from either HM or via online web page.
 

Andy Morris

New member
HI,

Thanks for your response.
I have finally tracked down the issue. I built this as a headless unit without display and buttons, using just the web i/f to control it. What I didn't do was tie the arduino pin used for the buttons to ground (via a 1k). I had left it unconnected and it was floating. I suspect that early parts of the cook were ok until the random floatiness resulted in it putting itself into the config part of the menu and then randomly configuring the probe offsets. I have applied a resistor and the first couple of 7 hours tests have been rock solid.

I have a further question. I am currently running this from a relatively high capacity Lipo battery and it works ok for several hours but it is possible to drain the battery below it's reccomended minimum limit so I was thinking of adding a battery guage to the web interface (not sure how yet :) ). Has anyone already done this and can offer guidance or point me at any useful collateral?

Thanks
Andy
 

 

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