The temperature protection thing is basically causing trouble without providing any significant benefit. By feeding these drivers with a precision power supply while installed on a pill with an emitter, I have noticed that the thermal stepdown starts right after providing power to the driver, so very quickly (PSU amperimeter reducing value). This is because the onboard NTC starts reducing its value very soon, after all it is in the driver which being linear dissipates any excess power and thus raises its temperature quickly (its expected behaviour). Since the temperature limit is 55ºC, it is pretty normal that current and power starts getting cut down almost inmediately.
In my opinion there is no need for temperature protection. If anything, temperature protection could be set between 100 - 120ºC (212 - 248ºF), to provide some long term protection to the device internals (driver, namely). This is because I don't think the flashlight needs to protect its user. Whoever burns his/her hand using the flashlight should deal with it and learn the lesson. Period.
P.S.: Considering flashlights are powered by li-ion cells 100 - 120°C likely is overboard. Maybe setting it at 85 or 90°C could be nice. Maybe.
Simon, I have noticed you now offer S2+ with red light. Does it mean that 2.5A red led driver fits inside S2+? Because earlier you said it was not compatible.
I think most people prefer not to burn themselves so 55-60C is probably sensible. A bit of testing last night showed that is seems to stabilise at around 25% after a few minutes on either 35 or 100% mode, so seems to be OK for my night photography use (as by the time I’ve gone back to my camera and focussed, set exposure, the output should be stable).
It is marketed for red leds, totally looking like a buck driver. ∅17mm. Two A19T MOSFETs behind, these must be for reverse polarity protection. The sense resistor stage is gross, with 0.1Ω combined, dropping 0.25V at maximum driving current; this is its only fault, reducing efficiency.
There is no reason for it not to work with any other 1S emitter.
Also there are likely many customers buying lights from Simon that don’t know how hot a li-ion powered flashlight can get, especially when left unattended. I’ve seen several people on r/flashlight that wrecked their older S2s by leaving them on higher output for ceiling bounce, etc. Sofirn for example ran into a similar problem when they were getting bad reviews on lights simply because they were getting warm on turbo. I can’t imagine the consequences reaction if these lights were sold without any sort of thermal regulation or even just timed stepdown.
Looking good.
For the 2.5V red light.
Did you have to solder the driver to the pill? Retaining ring?
Earlier in this thread Simon said the red driver wouldn’t be suitable for the S2+ pill.
