I'm only achieving 2.25A from a 3.04A driver

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Cowboysnavy
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I'm only achieving 2.25A from a 3.04A driver

So the title says it all
Here’s my specs
I’m using a qlite 3.04A driver
Moded with 18ga silicon wires
Tested with Sanyo red UR18650fm
And panny CGR18650 batteries
Freshly charged to 4.21

I’ve also takin the pill apart now to test on a huge heatsink with a fan blowing on it just to see if it was from heat sag and still no go I’m only achieving 2.25A in and out of the pill
Any suggestions would be highly appreciated
R/
Cowboysnavy

18sixfifty
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Not much help here, but I stopped using the Qlight driver because I had similar problems with them as well.

I’m a junky, I mod lights so I can sell lights so I can buy more light to mod so I can sell lights to buy more lights to mod.

Ouchyfoot
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Maybe a couple of the AMC7135 chips aren’t soldered down properly. Check with your DMM.
…or maybe some chips are DOA.

comfychair
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What LED?

And, what does that exact cell run at when connected to that exact LED in direct drive?

texaspyro
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How are you measuring current? Many DMMs/leads have a high enough resistance on their current ranges to substantially affect the current readings.

Cowboysnavy
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It’s an XML-U2
As far as DD I don’t know
I just soldered a new qlite to the same led and I’m getting 2.54A now
From this I have to assume a bad batch of driver

Cowboysnavy
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I’m measuring with a greenlee dmm and it’s sad to say but double checking results with a harbor freight freebee

TSellers
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Quote:
From this I have to assume a bad batch of driver

Or perhaps an emitter that is only drawing that? Won’t know until you get that DD test done as noted by Comfy?

Regards, TS

texaspyro
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I’m betting that your meter/leads is the source of the error…

Cowboysnavy
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Ok thanks guys I guess that’s my next step thanks for the info

comfychair
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These type of drivers don't do any kind of fancy stuff like converting excess voltage into amperage, they can only limit the current. They're just restrictors. So the output cannot ever be higher than what that cell is capable pushing through that LED without the driver in the circuit, it will always be lower.

Add a temporary jumper from LED- to ground to bypass the driver, then recheck the tailcap amps. Take that number, subtract 5% or so, and that's the absolute max you'll ever get from a 7135-type driver as long as it's the same cell & same LED.

Cowboysnavy
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Thanks for the info comfychair that will deffinatly be my next step

RMM
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I will mirror what texaspyro said: how heavy are your DMM leads?  None of my stock leads have ever given me accurate driver/LED measurements.  Here's a test: try measuring at the tailcap through the meter, then short one of the leads across to the body.  If you can see the light get brighter then your leads/meter are restricting a significant amount of current.  

It is possible that the driver is bad, but most of the problems from what I understand were from the first few batches of qlites.  I have tested several that I have added/subtracted chips from and zener modded and they all have been good so far.  If the driver truly is bad then either I or IOS (depending on who you purchased it from) will make it right.

Mountain Electronics : batteries, Noctigon, and much more! What's new? 

Cowboysnavy
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Thanks guys
And thanks for the tips
As I’m new to this they are very helpful
Now that I have some more knowledge I’m sure it is very possible my cheap dmm could be to blame

TSellers
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All the Qlite’s that I have received from IOS in the past months seem to check out around 3A. The only problem I’ve had is one of them went into direct drive mode, Hank replaced it by adding another one to my next order.

Regards, TS

ChibiM
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Or change the battery in your DMM!

DB Custom
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When I was first getting started my tail cap amperage readings were always way below what everyone else reported. I took a few inches of 12ga copper wire from some household Romex, bent one end over to double it so it would go in my DMM and used these for amp readings. Voila! Similar readings as what everyone else reported. I've since gone to Tenergy Silicon insulated 12ga wire with banana plugs on each end, same 12ga but very flexible. Makes it easy and accurate to get the readings.

And then there's what comfy said, the cell itself many times can't perform to the driver's max. Make sure you're using good cells, like the Panasonic NCR18650PD which will easily do whatever the Qlite or XM-L/XM-L2 will do.

TSellers
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Quote:
Make sure you’re using good cells, like the Panasonic NCR18650PD

Just made me want to confirm, I do have some ‘PD’ cells, but I normally use a Panny NCR18650B when I take these readings because they are always close at hand, I think I just assumed it could easily provide a minimum of 3A draw?

Regards, TS

Cowboysnavy
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Well I did the jumper on the negative to ground
It lit up for about 1sec absolutely beautiful
Then it died
First led I’ve fried but I’m sure it won’t be the last

TSellers
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Ouch! Check, I’ll bet something fried on your Qlite driver, I’m guessing if you put current direct to the emitter you’ll still get light.

Regards, TS

comfychair
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Ouch. Sad

Did you use the ammeter in place of the tailcap? If so, that's a hint that the meter isn't the cause of the low amp readings.

comfychair
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TSellers wrote:
Ouch! Check, I'll bet something fried on your Qlite driver, I'm guessing if you put current direct to the emitter you'll still get light.

Jumping LED- to GND won't hurt a thing on that driver, it just bypasses the current-carrying section of the 7135s.

Cowboysnavy
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Nope I was trying it with the tailcap on first
But it’s the LED that fried I’ve already checked it so
Mistakes cost money good mistakes “lessons learned” cost even more

LinusHofmann
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Cowboysnavy wrote:
Well I did the jumper on the negative to ground It lit up for about 1sec absolutely beautiful Then it died First led I’ve fried but I’m sure it won’t be the last

Ah man that sucks, frankly I don’t feel comfortable recommending doing direct drive tests exactly because of this possibility.
Depending on the type of cell and the resistance in the circuit you can pump some potentially very dangerous current through the led. I know we can all get complacent with seriously overdriving these leds because usually they’ll take it fine. But any time we push them above their maximum current rating we’re flirting with the possibility of a dead emitter.

XM-Ls are tough but not invincible and imho direct driving should only be done if you have a bit of experience with the setup and you’re happy to replace the led should it go pop. Maybe we could just add a little disclaimer in future when we recommend a DD test to someone who may not be aware of the risks.

Cowboysnavy
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I might have to make that last line my signature
Atleast I know I got batteries that can push some current

TSellers
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Quote:
Jumping LED- to GND

I should have elaborated more. I’m speculating that an errant conductive source may have caused an inadvertent and unnoticed short on some of the driver contact points in the process. Proabably worth checking before throwing a possibly good emitter out.

Regards, TS

Cowboysnavy
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Driver is still working great
I just soldered it up to a pt54 red LED
I know it can handle whatever you throw at it
So I tested it in DD and I got a reading of 11.47A ( I’m suprised it didn’t blow the fuse in the dmm)
And 2.74A through the driver so I’m sure it’s my dmm that’s to blame
I love the pt54 it’s built like a tank and it comes with a pretty massive heatsink

DB Custom
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Sounds like you tested the PD cell, and that's why the emitter blew, can't handle over 11A even with a good copper heat sink.

When you were first asking, the cell you were using is...I think...rated at just over 4A. That one should'nt have hurt the Cree emitter. The PD is a different story.

Cowboysnavy
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That test was with the Sanyo red cell
They seem to be great battery pack pulls

DB Custom
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Yes they are, I am using them myself. I had my MT-G2 in the Solarforce M8 running direct drive. With 2 18650's the Sanyo FJ cell allowed 7.51A, Samsung 20R allowed 12.18A. I could run the M8 with a McClicky switch using the Sanyo's, was scared to attempt it with the 20R cells. lol Now it has a driver in it and is pulling 3.74A through the Sanyo's with 2 extra chips on a Qlite.

Hope you find the problem! I use Qlite's all the time, probably put in over 30 of em. Have 10 sitting here waiting their turn. Wink

LinusHofmann
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I tend to approach it like this… a fully charged 18650 DD to an XML = potentially unsafe current levels.
How unsafe is arguable and there’s too many variables involved to really work out exactly what the max current will be and for how long before the cells sag or at what current that particular emitter will go pop.

So in general I think it’s best to just be cautious with any DD test especially if you want/need the LED to still be functioning afterwards.

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