Such madness. Once again you've modded a light I want to mod.
Racer, that is amazing! I'd be giddy as a school girl after her first kiss with that light too!
Only one 17mm fet driver is running the whole show? What does adding the second fet do? I needs to know. :D
Wow! I love it R86.
That tail twisty is way past my skill set. It makes my brain hurt just just trying to figure it out. Two minutes of insanity. It’s the kind of light you only turn on if there are people around to see it.
Mine is still in the box. I haven’t had the energy to deal with twelve emitters, and I didn’t even think about what would happen to the switch.
What does stacking an extra FET accomplish?
:)
And Im already looking forward to my next big mod. Hopefully it will be a success. Im making a nice TRIO of powerful lights. The BTU shown in OP might not make that TRIO. ;) I think you might like the lights I end up with.
Im usually doing lots of small lights in between working on larger mods mods, so it might take some time before Ive got my full trio done. Still some weeks until its properly pitch black dark outside too.
Thanks JM and Ouchy. Im not sure how healthy it is for one of those FETs to have 30A flowing through it continuous. So I added another one so that they could share the load. I tried to find the correct datasheet, but not sure If I was looking at the right one. Maybe someone can tell me if that was necessary and how much the typical Vishay 70N02 are rated for.
I knew others had done around 15A through them in flashlights. So with 30A divided on two, I should be looking at around 15A too, which I believe should be fine. Two FETs also means a tad less resistance than one. As seen by lots of the wiring and tailcap. I tried to make everything capable of high amps with little resistance.
What do you think the current would be without the stacked FET?
All I know is that I have the FET driver in my hand that’s going to replace the one in my 2xMTG + 2xXML light that I cooked the MCU in. I’m going to take the FET off the old one and stack it on top of the FET in the new one. It can’t hurt, and I’m curious see if the current goes up.
Comfy or someone that are into these FETs or more into electronics can probably tell.
As long as the FET can handle 30A continuous, Im guessing barely any difference. There is not much resistance in them. As mentioned, I was not sure what its rated for. I prefer to have some "headroom", and hopefully I got it.
Halving the resistance in the FET by adding another one in parallel doesn't gain much, since the resistance is so low already. If they were crappy 30 milliohm DTU FETs you would see a big gain, but the better the FET is the less you get by adding more. Diminishing returns approaching the zero bound or whatever...
What's the battery layout? 2S3P?
Its simple. Ive seen what you can do. You do way more tricky stuff than that.
Extra wires just go from the springs to one copper plate. Then from another copper plate to the screws that attaches to the body. Once the tailcap is properly tightened the two copper plates gets connected.
I could have used 18awg wire instead of two 22 awg as an example. But after it was supposed to be finished I decided to add more.
Its nice to not have to worry about the resistance in the tail.
Yupp.
What are the FETs rated for? (continous amp)
Okay. I think I’ve got it. All those wires lake it look confusing. Things are always easier to figure out when you’ve got the actual part in your hand. Actually, I may experiment with that on another light.
http://75.65.123.78/pdf/SUD70N02-03P-E3_72246.pdf
A lot. I don't know enough to be able to translate those specs given at different voltages than what we use, but I don't think a single FET would be in any danger.
Wow, just wow! I think the double FET is a good idea, though maybe not much of a difference in output as comfy says. I've been wanting to try that. Maybe do the cap trick of batt+ to ground as comfy found, if you didn't already. Having the 6 cells is a big plus for this host, as opposed to the J20, though the J20 has that massive head.
My 7k+ lumens J18's also throw incredible, not as much as this, but still amaz'n for a flooder.
I find these FETs in the drill packs at the recycle bins. Check the amp draw and the low drain-source resistance
Total gate charge = 160nC, unable to be driven directly by an attiny13. Gate charge has to be around 40 or less. This is the problem with ultra-high performance FETs, if they can do huge current at low resistance, they can't be driven directly without adding other parts, like high-power gate drivers. FETs that are easy to drive have lower performance. There isn't anything out there that has a better balance between those two things than the Vishay 70N02, not by a long shot.
The gate load presented by two FETs in parallel could also be an issue with RaceR86's driver not working correctly (though there are other things to check first, reverting to a single FET for testing wouldn't be a bad idea).
Who was that that had a pic of a driver, East-092 style, that had a stack of FET's a mile high? Dunno if it actually worked -- I just recall that picture in my head. Think it was someone who really knew their stuff in EE though...
Holy MOG! You crazy off the charts Norseman. I guess it's true what they say about intelligence and insanity.
P.S. How are the emitter's wired? It appears 2S6P.
Oh my gosh!!! That light is sick! I am so jealous now………………………
Wow that is insane.
I have pmed with other guys here about these light and a similiar mod….but a direct drive with XML2s…wow
I think a second FET is good at this currents because even if resistance is low the power loss is huge at huge currents and 30A is mega high current, you should solder GND wire also direct on the FET because I wouldn’t trust the copper paths with this currents…I also think that one FET without heatsink can smoke away…
The power over a resistor rise with current power 2……P=I^2*R
So 0.0033×30^2=3W loss in one FET…if you use two 0.75W loss per FET.
The 70N02 is from the specs definitely a very good one, sadly it’s not available anymore for cheap