Lid open switch

[I Roots]

Hi all,
Would it be possible to wire a microswitch to put heatermeter into lid open mode if the lid/door was opened? Any idea where to connect it on the board?

 

[Steve_M]

You would wire it into the Left push button points, as the left button is what triggers lid open / close.

I'm pretty certain that you need to press and release the button, so just having a microswitch or magnetic reed switch wouldn't be ideal because those would be basically holding the button while the lid is open. Another things I know when I trigger lid open mode, I let it turn off by itself after I close the lid so that the pit can naturally correct itself. If the pit temps drop quite a bit with the lid open and you close the lid and auto-trigger the cancellation of lid-open mode, your blower will kick in ASAP and there's a good chance you'll overshoot your target temperature.

I made a headless waterproof case with only a "lid open" button on it and it's been working great.

 

[RalphTrimble]

Like Steve said, a simple microswitch wont work because when the lid was open it would be as if the left HM button was held down. Hold your left HM button down for a bit and you should see why you don't want that. You could rig up a cam with a bump that clicks a microswitch just once when opening and again when closing to achieve a manual lid switch, or I guess there are a couple electronic ways to achieve this, but I agree the software trigger is what you really need. It triggers fine and the timer can be useful to keep overshoot in check for low and slow cooking.
One thing that I DON'T like about lid mode, the shortest period you can choose is 30 seconds for some reason? I would much prefer if the time could be set all the way down to 0 seconds (to disable lid mode), I see no reason to block setting shorter lid mode times....

 

[Bryan Mayland]

One thing that I DON'T like about lid mode, the shortest period you can choose is 30 seconds for some reason? I would much prefer if the time could be set all the way down to 0 seconds (to disable lid mode), I see no reason to block setting shorter lid mode times....

Because lid detect mode can't auto-disable in under 30 seconds. I always hit the lid button before I open the lid to do any work so it would automatically disable lid mode 1 second later if the temperature is over the setpoint. Because of this, the temperature isn't checked for 30 seconds after the lid mode engages.

30 seconds does seem a bit long but 10 could be too short for someone to press the lid button, get their mitts on or pick up their tools, and actually get to opening the lid and having the temperature drop below the setpoint. If you're going to wait 20 seconds might as well make it a round 30 seconds, right? Lid detect mode can be disabled by setting the percent to 100%, which isn't the most intuitive either, but I feel like it is just about as bad as having 0 seconds mean disabled but 1-30 seconds will reset to 30 seconds and requires no extra code.

As everyone else has pointed out though, the problem with a real lid switch is that HeaterMeter doesn't want a true switch that is the position of the lid but rather a toggle. If you do manage to turn a microswitch into a one-shot button press, then you could run into problems if you open the lid and the lid countdown expires (going back to normal mode) then you close the lid, it will switch back to lid open mode despite the lid being closed. You lose that extra information which is the actual lid switch information.

 

[RalphTrimble]

All reasoning aside, is there a technical issue that prevents the lid timer from going all the way down to 0 or 1?
As for the mechanical momentary, if you set the timer really high that shouldn't be an issue. Is there a limit on the timer at the top end too?

 

[Bryan Mayland]

The only technical issue being the one that already has been mentioned, which is a usability issue. It used to allow 0 second durations until I added the code to make it work better. Disabling the lid autodetect is still possible so there's no loss of functionality.

There's a 1000 second upper limit on the timer (16+ minutes) but just counting how many times the lid opens and closes is just a recipe for things getting out of sync for some reason at some point in my book. You also don't want the lid mode to disable immediately when you close the lid anyway, because you'd get a giant overshoot.

 

[RalphTrimble]

I agree and prefer the timer to count down to prevent overshoot, but we both run kamado's... I can imagine there may be another grill configuration that may benefit from faster stoking after lid openings (offset smoker perhaps?). At any rate, I always air toward more flexibility, so if lid mode could go down to 0 seconds I say why not let it?
I've heard the topic of mechanical lid mode switch raised a few times, though it's not something I would use, to each his own I guess?....

 

[Bryan Mayland]

if lid mode could go down to 0 seconds I say why not let it?

To gain what?

 

[RalphTrimble]

I guess technically it would be to gain the ability to set lid mode from 1-30 seconds, and perhaps have a more intuitive way to turn it off (0%). Neither a big deal, it just strikes me as odd that 0-30 would be disabled.