Hi,
I currently have a Tr-J18 that I think has a blown driver. Like a few other people I’ve been reading on here, the light has suddenly lost most of it’s power. I have tried by-passing the tail-cap and there is no difference. New batteries do not seem to help.
So, this leaves me with 2 options.
1) Contact the seller and ask to have the light fixed or replaced (it is only about a month old).
2) Mod it… for a bit more “ooo.. wow” factor
Please bear with me though as this would be my first modified flashlight, and first time modifying a flashlight. To be very honest, this light is only really for the “oooo.. wow” factor. For daily use I use a few single mode G10’s with 14450’s in them and a couple of smaller single T6 lights.
What I am looking for out of this light.
a) Ability to throw a “lot” of light for short periods of time… say few mins? More Specifically, I want to ensure there is no doubt that when you turn on the flashlight, there is more OTF lumens than a Coast HP21.
b) Ability to turn down the light and light a room, 30-45 mins runtime here would be ok
c) Ability to run on 18650’s. (currently using 3 18650’s. TF flames). I want to try and avoid the initial purchase of 26650 batteries if I can avoid it do to cost.
Looking around, do see a few upgrade paths but am not sure what are the pro’s and cons of each route. Or if one driver is “better built” than the other one
Option One
http://budgetlightforum.com/node/12661
modify the existing driver. This seems difficult (as I’m not that skilled soldering) and may not even work as I think my existing driver is blown. Furthermore it seems that there are more than one driver shipped with this light.
Option 2
http://www.intl-outdoor.com/boost-7led-3-modes-23-cells-input-circuit-bo...
Seems like a good option
Option 3
http://www.kaidomain.com/Product/Details.S020417
Also seems like a good option.
So, between the 2 drivers, besides the number of modes it has, are there any real differences that would make one better than the other?
Also, it seems like none of the drivers ships with the battery spring in the middle. Where can you buy this spring (and of the correct size).
When installing the driver, do I just connect the existing wires black to black and red to red…. The driver just sits in the head? (no glue or tape).
Finally, does the tail cap switch need to be upgraded to handle the increased current? If so, where you would you get the parts for it?
Are there any good walk through’s posted that can how me “how” to upgrade the light? I think I have an idea but a few pictures would make life so much easier.
Thanks in advance for your help, and sorry for the noob questions.
You could try this one from KD. You will need to rewire the LEDs for series instead of parallel.
Here is the same driver with special firmware ; gives three-modes, 100%-30%-5%.
Good luck with your mod!
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relic38
Thanks for the suggestion, that driver does look good too

Just one question tho, I was under the impression that the J18 ran the led’s in series from the factory. Can anybody confirm.. or.. is there an easy way to check?
While I can get to the driver, I have yet to figure out how to take the head appart to get to the led’s.
I’m pretty sure it’s parallel. Most of the factory multi-emitter lights like these are parallel. If you can get the reflector off, it should be easy to do with some basic soldering skills and good wire (recommend silicone wire, 22 AWG, no smaller than 24 AWG).
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We be talkin’ bout the LEDs
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Which are also in series.
OK, sry, I must be mixed up with another light then. Maybe the J12? Anyway, if they are already series, then the KD drivers are the best bet.
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wow, thanks.. yes the second “reprogrammed” KD driver looks good. Modes are perfect. One questions is that will this driver work with 3 cells? I reason I was looking at the IO driver was that it states it will operate on both two and three cells.
I’m currently using 18650 TF flames and I am not sure if they have enough “guts” to fully drive the light with only 2 cells. Furthermore, I’m worried the increased amperage from running 2 cells on a modded light will just smoke the parts inside (tail cap switch + springs, etc).
Yes, that driver will work with three cells. If you plan to run 2 cells, you will need to get better cells, possibly unprotected cells or 26650’s. The KD drivers could pull up to 5-6A from the batteries. The switch can be a problem at those high currents. I’d recommend 3 cell operation, monitor the cells, and even though it’s a thermally protected driver you should limit the run time on high.
A final note on the LED configuration (series vs. parallel). I looked around, and there definitaly isn’t a consensus on how the J18 LEDs are wired. The best way to know is to check it yourself. If your flashlight still lights up at all, put a volt-meter across the LED wires coming from the driver; if you measure 2.5-3.5V it’s parallel, 17-20V and it’s series.
Better to be safe than blow up another driver.
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Yes the light still works, it is just very dim. I tried by-passing the tail-cap and there is no difference.
In this case, how would you go about measuring the volts to the led’s? The wires/contacts are in the head and if I pull the driver out to gain access to the wires I can’t turn on the light (battery tube is disconnected). Sorry if this sounds like a really dumb question.
Jon.
I’m not 100% but the reflector is screwed in from the back, pop the driver, if there is a screw in there, its probably holding the reflector down. If not, unscrew the bezel on the front, remove the lense, the reflector should just come out then and you can see the led stars.
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Good point. I have a bench power supply that I use for this. For some reason I assumed everyone has one. oops
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I am wondering about the same things for my j-18. please let us know how this goes for you. and if it is the right driver. thanks I think my j-18 could be brighter , It is only about as bright as my SR King now. I tried three 26650 s but they were a little too long so I’m running it with two 26650s and one 3400, 18650.
Mi Bill, I’m sure somebody more knowledgeable will chime in soon but my understanding is your should ALWAYS run matched cells when having batteries in series. Unmatched could cause really big problems (read explosion).
As for the drop in power, mine was fairly noticeable. I means when I first got the light it was bright, bright enough for it to be unusable in a room. It also had the power to basically completely wash out a single t6 light.
Now, the flashlight is easily overpowered by a single T6 light
http://imageshack.us/photo/my-images/811/dsc70951.jpg/
http://imageshack.us/photo/my-images/18/dsc70941.jpg/
The light on the right is a UltraFire KF-T60. This is a heavily used and fairly old T6 light I have. Both lights are on high for the picture. The result is also the same if I run 2 or 3 cells.
yes Jonney_ Boy I think we could benefit from some electronic parts.
I measured a UV S5 (SRK) at 2159-2077 lumens, and a TR-J18 at 3808-3155 lumens (1st reading is at start, 2nd reading is at 30 secs). Definitely noticeable the J18 is brighter.
that is what I read so I sent for one but they seem about the same brightness.
Ouch! Something wrong there, definitely. I'm running TrustFire 5000 26650's, but tried 18650's but only tested the output with 26650's, but it looked about the same.
That is good to know. I may be able to improve the tr-J18. I tried some king kongs but they were a little long. now I’m using 2 trustfire 26650 and one Panasonic 3400 protected 18650.
Interesting combo... I ordered 4 of the TF 26650's from FastTech when I ordered the J18 from them. Did you try the 2 26650's by themsevles? Wouldn't recommend you run them at any length of time (melts springs), but just to see how they work.
yes I also ordered TF 26650’s from fast tech, I ran the J-18 with two of them and it was dimer with just two. let me know if 3 of the TF 26650’s fit. I also wound some solder braid around the tail spring.
3 26650's definitely fit - I'm using the light that way. I got some wall beam shots - need to post them FF STL-V2 vs. SRK vs. TR-J18.
Slight update,
Parts are ordered and on it’s way. I ended up picking up the KD modified driver along with a bunch of AA/AAA springs. We will see how it goes in a couple of weeks time when I try and swap this driver in.
One question I do have tho is, is there a “need” to attach the driver to the flashlight?
What I mean is, when I took the original driver out to look at it, it was just sitting in the flashlight, held down by a spring (which is in turn held down by a retaining ring).
Looking at the guide for the driver upgrade on the smaller Tr-J12, I see that they where destroying the original driver to get it out, followed by soldering the new one into place… Do I need to do the same on the Tr-J18 or does the new driver just ‘drop in”?
This is a pic of my J18 driver: http://budgetlightforum.com/node/12661#comment-289413
Can't recall exactly, but didn't have to do anything nasty to get it out or get it back in. Think I describe later in that thread how to remove it.
To install the new driver, you will need to de-solder the + and - LED wires, then solder them to the new driver at the places indicated for the + and -.
I ordered the I-O driver, looks the same, specs are the same, little cheaper, great support from Hank at I-O, rated for 3 batts, includes thermal pad.
Thanks Tom,
Yes I can get to the driver the same as in your pic, unscrew the battery tube, take out the retaining plate and the driver just “falls” out.. I guess there is no need to solder in the new driver (onto the head) as shown in the thread where they modified the J12’s… yay
Now, my next noob question. What is the thermal pad for? From what I see the driver just “sits” in the flashlight. There is not any “flat surfaces” for you to “glue down” the driver.
Actually I emailed Hank about the thermal pad - it goes in between the 2 boards. Haven't gotten the driver yet and haven't worked with a double board driver before, so not sure exactly how to fit it until I get it and see. I know the 2nd board just dangling by itself hanging by wires is probably not good - you want a path for the heat to go along, escape to. I think guys have been potting the driver in these cases, not sure (potting is taking thermal grease or epoxy and smothering the driver, and maybe filling the inside of the pill).
Got the I-O driver, installed it, wow! just wow! 3 simple modes, easy to install, fits perfect, sandwhiched in the thermal pads it came with between the 2 boards, cutting into pieces to fit. Measurements of the J18:
Before with 3 TF 26650 5000 batteries, as is, not fully charged but in the 4.05v range:
tailcap reading: 3.8A down to 3.1A, fluctuates, usually dropping steady
lumens: 3330 @start, 2940 @30 secs, throw: 34 kcd
After with same batteries as is, not charged in between:
tailcap reading: 5.78A
lumens: 4930 @start, 4726 @30 secs, throw: 48 kcd
Waiting on the TF batteries to charge, takes long on an i4, but should get 5000 lumens.
Wow!
I see one of these drivers in the fit-40s in the near future, thanks for the update tom. Any ideas on a more heavy duty tail switch or are we crossing that bridge when we come to it?
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I'm taking my caliper home with me to measure the driver for my UniqueFire S7; if it's the same size, I'll be checking the possibility of completing either the resistor mod or hitting up I-O for the high-power driver. I'm just not as satisfied with my S7 since I have my King clone which is not quite as bright, but too close for the difference between a 3-LED and 7-LED light.
Anyone with experience with the resistor mod; what wattage resistor should be used? and what's a good source for a single low-resistance resistor of the appropriate sort?
Keepin’ the “B” in BLF
Dunno what to do about the switch - where do you find better ones? Only thing I've seen is where O-L makes them out of copper - no idea how he does it, amazin stuff though. There is a lot of power going through it. The best I see is the conventional type rated for 2.5A, 240v. Can't recall now what's in the J18, though I had it apart a couple of times - it was flaky when I first got the light, did something to fix it, maybe just tightened it up, re-assembled.
That’s my problem, the only high current switch I’m aware of is that mega bucks mosfet jobbie, not seeing that myself. I suppose the other answer is braid the spring and buy in a rook of switches, just swap em when they burn out.
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