direct drive xp-g-r5
- Thread starter LED4LYF
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Hi LED4LYF,
Welcome to CPF.
There is definitely something wrong. Hooking up an 18650 directly to an XPG R5 will very quickly run it to between 1.8 and 2+ amp. To get the drive current down to an acceptable range for direct drive, I had to almost completely drain the cell.
It seems unlikely that the PCB on your cell is causing this, unless the PCB is defective.
Are you hooking this up directly to the cell or is this being done in a light with a driver?
Welcome to CPF.
There is definitely something wrong. Hooking up an 18650 directly to an XPG R5 will very quickly run it to between 1.8 and 2+ amp. To get the drive current down to an acceptable range for direct drive, I had to almost completely drain the cell.
It seems unlikely that the PCB on your cell is causing this, unless the PCB is defective.
Are you hooking this up directly to the cell or is this being done in a light with a driver?
bigchelis
Flashlight Enthusiast
MrGman tested a P60 direct drive XP-G R5 with an IMR 18650 and a UCL lens Surefire 6P.
It was pulling 1.8A turn-on and the 1 second lumens were 200ish OTF, but 100ish at 3 minutes.
No direct drive unless you want low lumens.
It was pulling 1.8A turn-on and the 1 second lumens were 200ish OTF, but 100ish at 3 minutes.
No direct drive unless you want low lumens.
Justin Case
Flashlight Enthusiast
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- Mar 19, 2008
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That 1 sec measurement seems anomalously low. At 1.8A drive, the XP-G should deliver around 500 emitter lumens. It's hard to believe that heat losses after only 1 sec and optical losses would combine to be potentially about 60%. Any explanation? How much error is introduced if the light being measured differs from the spectral output of your reference (calibration) source? For example, let's say your reference source uses a Cree LED in chromaticity bin 1D or 2A (or around the old WD). Now you test a light that is in chromaticity bin 0A or 5A or even 6A. What is the effect on measurement error, if any?
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So are we talking about just the led, a resistor, some wire, a cell, and your DMM? No light? If no was the emitter on a heat sink?
My first guess would be to remove the resistor, and quickly try a touch to the battery with every thing else the same. You may even want to do the retest without the resistor using a battery that is slightly depleted.
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Blindasabat
Flashlight Enthusiast
If I plug a 1 ohm resistor, a 4V cell, and 250mA into LED Pro, I get a Vf of 3.75V. But since 1) XP-G are supposed to be much lower than that, and 2) I have found that I need to add about another 0.3-0.5 ohm to account for the for LEDs own resistance, I then tried 1.5 ohm and get a slightly lower 3.62V Vf which still does not make sense. It should be just under 3V. Assuming nothing is wrong with your LED, I think you may have some contact resistance. Are you just touching the wires to the LED and cells?
Now assuming your cell is partially discharged and plug in 3.6V, I get 3.22V Vf. More reasonable. What is the voltage of the cell you are using?
Now assuming your cell is partially discharged and plug in 3.6V, I get 3.22V Vf. More reasonable. What is the voltage of the cell you are using?
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It realy is just going to be a process of elimination here.
I agree with what was said above about needing to have the wires soldered to the led. Its ok to have one or two spots where you are just "touching" the wires, but at the very least you need good solder joints to led.
Now just eliminate one possibility at a time.
Worst case here would probly be a defective multimeter (DMM) I have had this happen before. A cheap DMM will sometimes measure voltage ok but not current well at all. In fact it will cause almost no current at all to pass through, like in your case. Try hooking up the led without the DMM in the circuit and see if the led is noticeably brighter.
Unless you have an extra led you can try with this setup for now we will have to assume that your led is good. I have worked with a small pile of these, and so far I have not had a defective one so its probly a safe bet.
Once you have the joints to the led soldered (if they aren't already) I would try changing the cell as the variable first. You could use 3 nimh cells in series with some charging magnets or even tape as long as you have good solid contact. Re-test using everything else the same.
If this does not give a significant increase in current then you know the battery is not the problem.
If that does not work then I would still dump the resistor next. It may be that it is bad or miss marked value. Remember when you do this to use the 18650 at a slightly depleted capacity, even at 3.9v open current you will still drive the led quite hard.
By the time you have done each of these tests carfully you will very likely have a working light.
I agree with what was said above about needing to have the wires soldered to the led. Its ok to have one or two spots where you are just "touching" the wires, but at the very least you need good solder joints to led.
Now just eliminate one possibility at a time.
Worst case here would probly be a defective multimeter (DMM) I have had this happen before. A cheap DMM will sometimes measure voltage ok but not current well at all. In fact it will cause almost no current at all to pass through, like in your case. Try hooking up the led without the DMM in the circuit and see if the led is noticeably brighter.
Unless you have an extra led you can try with this setup for now we will have to assume that your led is good. I have worked with a small pile of these, and so far I have not had a defective one so its probly a safe bet.
Once you have the joints to the led soldered (if they aren't already) I would try changing the cell as the variable first. You could use 3 nimh cells in series with some charging magnets or even tape as long as you have good solid contact. Re-test using everything else the same.
If this does not give a significant increase in current then you know the battery is not the problem.
If that does not work then I would still dump the resistor next. It may be that it is bad or miss marked value. Remember when you do this to use the 18650 at a slightly depleted capacity, even at 3.9v open current you will still drive the led quite hard.
By the time you have done each of these tests carfully you will very likely have a working light.
Then it wasn't direct drive. 1 ohm would drop .25V at 250mA, so it sounds just reasonable if your battery was mostly discharged? I'd assume you're using a freshly charged battery, but you didn't say...
The batteries just came from all-battery.com so no I have not chared them. It was reading 3.8v. I guess I assumed they would be fully charged. But after reading some stuff on this forum, I guess a fully chared battery would be 4.2v li-ion.
Cool I hope that is the problem to. I will try that. One more question for you.
I am going to actually send the tenergy batteries back and buy some AW 18650 from the marketplace.
My question is will the AW 18650 with protective PCB work with a MAXFLEX V5 driver? Or should I just get the 18650 without the PCB in them? Will the PCB affect the maxflex at all. I am going to really push the maxflex pretty hard.
I am going to actually send the tenergy batteries back and buy some AW 18650 from the marketplace.
My question is will the AW 18650 with protective PCB work with a MAXFLEX V5 driver? Or should I just get the 18650 without the PCB in them? Will the PCB affect the maxflex at all. I am going to really push the maxflex pretty hard.
That PCB is there for a reason, if your AW cells cut off while in use, you shouldn't be doing what you are anyway. Just my 2 cents.:thumbsup: Unless you are above 5.2 amp per cell I don't think the PCB will cut your power anyway.
That depends how many cells you are planning to use?
One 18650 could not do this, but it would probly work with as little as 2 cells. That way each cells only has to produce 1/2 the 7 amp current needed. Since you are planning to use 7 leds, efficiency would probably be better if you had 3 or 4 cells.
One 18650 could not do this, but it would probly work with as little as 2 cells. That way each cells only has to produce 1/2 the 7 amp current needed. Since you are planning to use 7 leds, efficiency would probably be better if you had 3 or 4 cells.
amigafan2003
Enlightened
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- Sep 2, 2009
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- 248
I think you need to put your project on hold whilst you do some more research.
The fact that you didn't know that a li-ion is fully charged at 4.2v (and not 3.8v) and talking about wiring up 7 xpg's with 4 li-ion cells scares the hell out of me.
That's not a dig but seriously, slow down a bit before you do something dangerous.
The fact that you didn't know that a li-ion is fully charged at 4.2v (and not 3.8v) and talking about wiring up 7 xpg's with 4 li-ion cells scares the hell out of me.
That's not a dig but seriously, slow down a bit before you do something dangerous.
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