I have a Trustfire J12 that I had bought a Kaidomain driver for, only to discover its junk. Before spending another $20 on one from LCK-LED and hoping that one works, I thought I’d try another idea. RMM told me that he used a zener-DD board on his and wired four of the emitters in 2s2p and added the fifth in series to both. That sounds fine to me, but I don’t like completely unregulated drivers. Sure, Turbo is fun, but I want medium and low to be consistent, not continually degrade with battery voltage.
To that end, I thought that the driver that Wight is developing, the 6x7135 w/ FET turbo, would be what I want. The problem is that I’ve been told that 7135’s blow up under 3s. And the spec sheet for the 7135 I believe says a maximum input voltage of 6v, but is that for just the control/pwm/input, or is it for the actual gated current path as well? Because the control leg of the 7135 is only going to see what the MCU gives it, and the MCU is already being fed only 4.3v, and already people run zener-105C drivers in 2s and that seems to work fine.
I’ve never done a 3S 7135 driver so I cant answer the question “will it work” but I can tell you that 6V spec is a hard limit, not just the PWM input. For my zener driver’s I just use FET’s so I cant help you there.
The Zener mod controls the mcu voltage so the pwm pin is regulated and the Vf of the emmiters drops the voltage so that the 7135s only see the excess voltage. I’ve personally tested them up to 3s cells to 3s LEDs but never installed it in a light due to lack of low voltage protection. Now, the changes in board layout allow one to keep lvp just by choosing the correct value for R1. Not sure if anyone has gone that far with it yet. You want to be a leader?
Richard put together a resistor package to give low volt protection to my BTU Shocker, I’m waiting for Wight’s 7135+FET turbo board to be released to actually try it. If it works then the BTU will get it as well. And if I can find a 9v MT-G2, the Trustfire X6 as well.
In the past year a lot of new ground was broken on this subject due to the advent of the MT-G2 and I’m pretty sure some others have taken it to 3s but you’re definitely on the leading edge with this so be prepared for unknowns.
The 7135 datasheet only rates it for up to 7V input voltage, although we know it will work at 8V+. It may also work at 12V+, but the main issue is that you will be burning off a ton of heat with fresh 3S cells.
Watts = Amps*Volts
If you are burning off the same amount of amps, the watts (heat produced) will be tripled with 3S cells vs. 1S cell. With the MT-G2 (2S cells; low vF compared to XM-L2) and fresh high drain cells you can overheat the 7135s unless you have at least 12-16 chips on the driver. With XM-L2s since vF is closer to input voltage less heat should be generated.
I intend to, again, as soon as Wight releases the final version of the driver, and Richard carries parts kits for it. I do have some heatsinks I can Fujik to the 7135s as well. And Richard, I’ll pay you $30 if you can get me a 9v MT-G2, if 3s will not pop such an emitter.