BLF A6 FET+7135 Light Troubleshooting and Mod thread

wow, that is more than anyone got yet, you must have had a very low voltage XP-L by chance. I have had XP-L leds that went to over 9A en ones that blew at 7A, so you may just be lucky with this one :-)

Good work Scot! You are now solidly addicted. :stuck_out_tongue:

I have one that’s doing 6.2A on a Samsung 30Q, an HI variant actually, but most don’t go that high. Like Jos says, it’s the luck of the draw.

Hey Dale, since switching to your method of using my clamp meter to Measure amp draw, my readings have gone up, a lot. Here’s another point worth noting, I took the battery directly out of the BLF light after testing and placed it in the A6 I won in your giveaway, and amp draw dropped to around 5.4. Edit 6.1a

Likely to be an emitter binning difference, each step on the bins is approx a 20% gain in output. We did see some dramatic shifts in the equilibrium when Cree made the last changes and high amperage is not common anymore, while output can very well be the same.

At any rate, a 500-600 mA difference is fairly normal between 2 identically built lights. It’s always difficult to get em exactly the same.

I’ve also built a light, ran the tests, wrote down everything as it happened only to come back later and find new tests give different results. The cells lose capability with age and wear, the emitters break in differently, whatever causes it, it’s a fluctuating set of parameters that befuddles me on a regular basis.

I'm loosing faith in my 14 AWG DMM lead setup now, after hearing these crazy #'s... Wow! Is there any reliable way you have to measured tailcap amps on the same setup you used the clamp meter on?

I'm seeing the same as you Dale. Generally months later, #'s go down, not always though. My triple X6 that was ~4200 is now like 3900 or so, for example. Cells sure do lose it. I'm think'n I'm not smart bout storing them lower - I tend to keep my cells charged up, which is probably not helping.

I also wanted to state that while the differing tube lengths are a crappy ordeal esp. for any protected battery people (although springs on both ends helps) that the tube length in itself shouldn’t affect power through the light. The problem it seems is the length of the threads and/or how deep the caps are threaded. You’re running out of thread before the un-anodized portion of the tube is seated properly. Also be sure that your retaining rings are tight as they need connection to their respective boards! As I and DB have mentioned be sure your tube is not reversed (clip slot near tail). I am already guessing you are thorough enough to have checked that. :wink: Please be aware that some of my posts are for anyone reading in the future as well.

Hi Tom, just measured the A6 that hit 6.7a on my fluke clamp meter. It reads 5.4a on my Klein DMM with 14” 12g a leads.

Occasionally I will interrupt the negative lead on the star and put a loop between the lead and the pad to clamp onto, thus getting an actual emitter amperage reading. I keep the loop as short as I can fit the clamp meter on comfortably, usually about a 3” lead.

12 ga solid wire from Romex in about 3” lengths and folded over on one end to fit in the DMM give very close to the same readings as my clamp meter. You just have to be careful not to be measuring something with more than 10A draw. My clamp meter reads up to 40A.

Hi Scott - hhmm, that's interesting. What exactly is the technique you are using with the clamp meter? It could be a true 6.7A, but maybe you won't see that high # when all is assembled and buttoned up? Usually a light box/sphere is the ultimate test, if you can test output while doing the amp measuring method, then test it fully assembled. I've seen my tail amp measurements reading low sometimes: output is lower when jumpered with the meter, compared to fully assembled (bypass's of course).

I'm thinking you are doing it with a heavy gauge wire at the tail end of the battery/light?

Clamp meter and short thick wire is the only accurate method to measure currents in that range and with voltages arround 4V. Regular multimeters have too high internal resistance and introduce large error.
I measure arround 5A with my Fluke187 and above 6A with the clamp.

I use another way that works well. I have a 0.01 Ohm resistor (1% accuracy, rated for 20A) mounted on a piece of brass with the leads soldered into a terminal block. Not on the picture but I use two 10cm pieces of massive copper wire soldered to solid copper clamps for connectors. I measure the voltage over the resistor, current is 10mV/A.

That is indeed more accurate than a multimeter but still there are 10mOhm plus two wires added into the current path (let us assume 20mOhm total including the connecting wires, connectors and soldering).

20 mOhm multiplied by 6A produces a 120mV voltage drop.

This may not seem much but with the exponential VA curve of the LED 120mOhm will give you a difference in the measured current of at least 0.5A. See the attached Cree XML diagram for example.

For comparison I use a wire for my clamp that is less than 2mOhm.

I'm not sure the connection set-up for the sense resistor gives another 10mOhm (I hope less), I did not check that but I can do that and report here, I'm curious too (not before tomorrow btw). The 0.5A drop at 120mA is also correct for the XP-L at 6A btw.

So. All the modes on the light work except moonlight. It is basically off. Do you think touching up the solder on the 7135 will fix this?

Battery charged? You could check out post 52.

I’d touch em all up… The first four modes run through the 7135 no fet. Then 7135 + fet on 5 and 6. If you have any modes at all with your light then 7135 is working. Others may chime in……

Programming?

I’m a modder and we are all more patient but I really don’t have a ton of time for troubleshooting. I’m not very happy about this.

It’s a freshly charged new LG HE2.

Actually dudunphy, that’s not quite right. ToyKeeper posted a list of how the two channels work together earlier in this thread…

The modes are:

Group 17135 power__FET power
Moon_0.8%…………….0
Low__8%…………… 0
Med 1__43%…………. 0
Med 2_100………….2.7
High 1_100………….22
High 2_100………….54
Turbo__0………………100%
Group 27135 power__FET power
Low__8%……………0
Med_90%……………0
High__100……………35
Turbo__0……………….100%

So, modes 1,2,3 work on the chip with no mosfet(or 1 and 2 in Group 2), all the other modes except turbo have a blending of the two. Turbo being 100% Mosfet for maximum output.

Point being that it might seem to be working “fine” on all modes save moon, with that one being off apparently. This is showing up as a common problem on this light, either they had issues with soldering the 7135 or they got some bad chips, which can happen.

Ok. I’m Pretty po’d now. Tried remelting the connections (they all looked pretty good) and still have no moon mode. Time to contact the professional guy. Waited over a month to get a non -working light. This sucks.

Crap. Sorry Gunga. Hopefully you get a new head and you’ll have a spare to mod in the end….

Also thanks D.B. I was trying to do that post from my smartphone in the middle of some auto repairs. The fun never ends! :slight_smile: :_(

Oh well. I think I have a friend who wants it. Warts and all. Thanks a bunch for the advice. Too bad it didn’t work. I’ve contacted the professional guy and will await a response.