Good Morning. Today I will teach how to remove the overheat protection on the Convoy M3 flashlight.
We start by removing the battery and removing the driver from the body of the flashlight

Here we take a closer look at the NTC resistance

Resistance measured at about 21ºC - 23ºC in the room

We heat it a little to confirm that it is the NTC resistance, with a hair dryer at 45ºC - 55ºC

As we see the resistance decreases

We proceed to desolder the NTC resistance with a fine tip soldering iron applying a little flux on the contacts to facilitate extraction

Closer, the pins mustn´t touch each other as it is an NTC resistor.

I will test with a Liitokala 26650 5000mAh battery (5.3mAh measured from 4.2V to 3V)

Battery mounted

Success, it takes more than 10 min in TURBO mode

IMPORTANT, do not keep TURBO mode too long as it shortens the life of the driver and LED. I only use TURBO mode when I am cycling as the wind dissipates the heat from the flashlight

I thank the following users for their help: Sidney Stratton jojosupir @PiercingTheDarkness



Buenos días. Hoy enseñaré a cómo quitar la protección de sobrecalentamiento en la linterna Convoy M3.
Empezamos quitando la batería y desmontando el driver del cuerpo de la linterna

Aquí vemos más de cerca la resistencia NTC

Resistencia medida a unos 21ºC - 23ºC en la habitación

La calentamos un poco para confirmar que es la resistencia NTC, con un secador de pelo a 45ºC - 55ºC

Como vemos la resistencia disminuye

Procedemos a desoldar la resistencia NTC con un soldador de punta fina aplicando un poco de flux en los contactos para facilitar la extracción

Más de cerca, los pines no se tienen que tocar al ser una resistencia NTC.

Haré la prueba con una batería Liitokala 26650 5000mAh (5.3mAh medidos desde 4.2V hasta 3V)

Montada la batería

Éxito, lleva más de 10 min en modo TURBO

IMPORTANTE, no mantener el modo TURBO mucho tiempo ya que acorta la vida útil del driver y del LED. Yo utilizo el modo TURBO solamente cuando voy en bicicleta ya que el viento disipa el calor de la linterna

Agradezco a los usuarios siguientes por su ayuda: Sidney Stratton jojosupir @PiercingTheDarkness

I have had a problem with the images. Already solved!
He tenido un problema con las imágenes. Ya está solucionado!

Good instructions, its mentioned HERE as well

Very well described and explained! Muchas gracias!

Lo sé, pero hice este post para facilitar a los nuevos encontrar esta información. Me llevó mucho tiempo encontrar ese post que mencionas :wink:

I know, but I made this post to make it easier for newcomers to find this information. It took me a long time to find that post you mention;)

Thank you for posting this. I love my M3 but I notice that it steps down without the light being hot. I may end up trying this!

Is the removal of ntc conected to lvp kicking in 3,7V for all modes or it was thermal paste problem you had?

If it is, a normal resistor could be soldered in, right?

I belive so but not expertise on this so would like to see my options here by someone who has done this already for final results

Thank you for this info!!

I don’t want to totally disable the temperature protection on my M3 but would love to increase the threshold a lot (by maybe 30 degrees at the driver). Can anyone suggest what resistor I would need to replace the existing one with? Or could I maybe solder a standard resistor in parallel with the NTC resistor to increase the overall resistance?

Thanks! Ben.

That’s a NTC Thermistors being used it’s resistance decreases as heat increases. So instead of parallel you would need to add a standard resistor in series. After that it’s beyond my skills. You could experiment with limiting its heat. Desolder the NTC place a thin layer of some thing under it and then resolder it. The gap off of the board with only the solder points as your thermal path may keep it a touch cooler.

Thanks texas shooter, I was wondering if “series” was actually the correct answer… I will look to see if there is a NTC thermistor with a different scale, so that the resistance doesn’t drop so low when it heats up. Or an insulator made with a few layers of Kapton tape may do the trick as well, like you mention.

I will also buy some thermal pads from ebay to increase heat transfer from the driver to the flashlight body, like someone else has already done here on BLF.

I am also thinking - if I fit the thermal pads I may just be able to delete the NTC thermistor without worry because my Efest 26650s probably won’t be able to maintain the voltage needed for turbo even for the 10 mins the OP reports anyway!

Sound like your on the right path. I was thinking of a couple of thin toothpicks under the NTC then pulled out after soldering. Put a real gap there. I’ve tried thermal pads, little improvement. Thermal epoxy gave better results. It increased the thermal mass and allowed the heat to conduct out from components. Then thermal pads to move it from the thermal epoxy to the head. Good Luck.

Good feedback on the thermal pads, thank you. Yes I can see how basically “potting” the driver in thermal epoxy would be great for heat transfer and something I had thought about as well. Thanks for all the ideas, you have given me a lot to think about. Appreciate it!