My guess is your batteries have to much voltage sag to run in turbo for any length of time. What batteries are you using and how old. They will also have to be fully charged in order to stay in turbo any length of time. The turbo step down I assume is looking for a set voltage (in firmware) from the battery while its under the load to trigger it.
Most 16340’s will not hold a voltage very well under a 2 amp or more load, a few can. The Trustfire 16340 does pretty well but the new Vapcell 16340 is the best I have tested.
I have tested several different 16340’s and the top 3 would be
- Vapcell - the most capacity with the least voltage sag
- Olight (ORB-163C05-10C has to be modified to work) - lower capacity but holds voltage well
- trustfire (red-gold) - a little less capacity than olight and slightly lower voltage under load
The Vapcell has the highest capacity with the least voltage sag under a 3 amp load.
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I changed the current on a Mi1c and ran into the almost instant step down until I used the trustfire 16340. Now I use vapcell for all of my high drain 16340 lights.
1100 lumen 16340 klarus Mi1C Resistor Mod
This may not be your problem but if you changed nothing else besides the emitter, it has to be either a bad connection or battery sag. The driver is sensing the voltage to low so it steps down.
As li-ion’s are used under a decent load they heat up internally which as they get warmer are able to give more current with less voltage sag.
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Just my 2 cents