Can I use my FET Drivers that have the zenor mod to allow for 2 li-on cells on a Single cell build. Bridge resistor how?

Flashlight Modding and DIY Parts
1

Hi all,
Can I use my FET Drivers that have the zenor mod to allow for 2 li-on cells on a Single cell build. ?

I have 3 spare FET drivers that I originally was going to use for MTG2 and XHP70 builds but now I want to build and use them for just an XPG2 build.

Thanks,
bigC

2

yep, worked for me.

3

PFFFFFT! Gone emitter!

The XP-G2, XP-L and XM-L2 are all 3.xxV emitters. Give em 8.4V and they’ll fry instantly.

The Zener diode keeps the MCU from getting over 5V so that it will still work, but power to the LED is not controlled by the Zener… the emitter will get the full voltage of 2 cells in series and will die immediately.

Not to mention that 2 18650’s will give far more amps to the XP-G2 than it can handle anyway, it’s limit being around 5A. The XM-L2 and XP-L can take more, or used to, with 7A+ being the top range. But still, if you don’t keep 8.4V from hitting them they’ll die instantly as well. Hence the need for a good buck driver to reduce voltage from the multi cell lights.

Edit: The Zener mod was developed to allow the use of 6V emitters on the FET driver, such as the MT-G2 and now the XHP-50 or XHP-70. These can handle the over-voltage and will rock with the FET Zener driver. They REQUIRE 2 cells, won’t work on one without a boost driver.

Edit II: I need coffee. Just reread the question and now I see what I missed. Yes, with a single cell the driver will still function as normal, BUT you won’t have Low Voltage Protection as that diode is replaced with a 200 ohm resistor in the Zener mod. :wink:

4

with the zener mod you wouldn’t have true reverse polarity protection from a diode, but the attiny should only see about –1V reversed with the zener mod. This might not actually fry the attiny (at least immediately), but I can’t really tell from the data sheet. I haven’t been bold enough to actually test this :bigsmile:

5

Yeah, I have the 6V FETs from Mtnelectronics which I will no longer use on XHP70/MTG2.

I would run the FET 6V with IMR 26650 and XPG2 on copper board. That’s it.

Loosing only low voltage protection is fine by me as long as it works. Thank you all for the quick responses.

best,
bigC

6

Here is what was advised by mtnelectronics......

"They sometimes work, but sometimes they start to glitch out when the battery gets lower because of the limiting resistor. Since you already don’t have reverse polarity protection, you can just bridge over the 200 ohm resistor and it will work without any issues. "

I have never done a resistor mod...where is the 200 ohm resistor on my board and what does Bridge mean? This is a 20mm single sided FET with just 2 modes. !

!:<

7

Bridge means to connect the two ends of the resistor with solder or a wire. The resistor usually goes in place of D1.

8

Yep, D1 on the board, the little black rectangular box marked 2000. It’s just under the red power lead in your picture. Simply solder over the top so both metal ends are touching and you’ll have bridged it. You can use a short piece of wire or copper if you’re so inclined as it can be difficult to get liquid solder to stretch across a gap.