TK
First off - thank you!
I’ll say I haven’t followed every minute of this behemoth thread, so pardon if this has already been discussed extensively…
My first thought is if we want the PID to function perfectly and be the sole method (over months and years of operation and thousands of samples!) keeping this thing from going to skin blistering temperatures is to have a dedicated thermal sensor as close to the (primary) heat source as possible. It’s very common practice now for bigger name manufacturers to have an NTC thermistor on the MCPCB. Measuring this far upstream will make it possible to get AHEAD of the temp control, and not require so much host calibration or predictive/preemptive throttling. One major concern I have with using the current temp sensor location, besides the obvious and previously stated shortcomings, is the driver retaining ring possibly coming loose on the F3WA. Most of you with a convoy tube light with right-hand-threaded tailswitch retaining rings has come across it loose over repeated use and battery changes. This could cause a serious change in thermal resistance in the sense circuit and potentially lead to extreme over temperature conditions. Small chance maybe, but one that’s avoidable IMO.
That said, if this can’t be done at this point in the project, then I really hope the safest and most reliable options are employed to limit the >1000 lumen modes. If timed step-down from turbo to high is necessary, that’s fine! Everyday carry is exactly what a light like this exists for, and no reasonable person would prefer burnt clothing and/or skin over an extra click to keep it in turbo if necessary.