help. Am I burning up drivers?

All of my latest P60 drop-in builds have not been working. Once I do all the soldering and go to turn it on they have all been DOA. I don't know what I'm doing wrong at this point.

Am I burning them up? I felt some were pretty hot when I've soldered the positive spring on to the board. Been working at 700-750F (370-400C) temperatures.

I'm using both the Nanjg 105C (here) and KD 7135 V2 drivers. Is there a way I can test them with my multimeter?

Very unlikely (But of course, not impossible) that you’re heating them enough to do damage. More likely cause is a solder short or improper connection.

Post a couple photos (high resolution if possible) of your ‘assembled’ driver. Those AMC chips can tolerate getting REALLY hot before they’re damaged.


I’m not sure what you’re trying to do, just solder the leads for the led and install in the pill or add 7135s and change modes but I’ll share what helped me.

My first attempt with drivers was adding 7135s to V2s. The first one went great so I thought I had it down and made two more and soldered them into their pills, both DOA. Decided I needed a way to check them every step of the way so I came up with this.

It’s just an XM-L on a heatsink I ripped out of an old PC motherboard. I used an XM-L because I figured I could push it pretty hard for a few seconds even when building drivers at 5.0a and maybe above. You’ll notice the LED is on one side so I can attach other stars if needed. I attached some AWG 20 silicone wire with clips for quick attachment to my drivers.

Now when I start with a driver I assume it’s ok as purchased (maybe incorrectly) and attache the output wires for the led and test measuring the amps. Set the modes and confirm my soldering again. Add one 7135 and test again noting the hi amperage. Keep testing until I’m ready to install in the pill.

This way, if it doesn’t work in the pill I know the problem occured on my install. I don’t have to go back and try to figure out which solder I screwed up out of 5 or 10 because I know it worked just a minute ago.

I also keep some notes (downstairs right now), don’t remember without looking but I believe grounding the - pin from a 7135 to the outer ring of the V2 and you have a 1 mode direct drive, complete two of the three pins on a 7135 without the -and the LED comes on for a brief second then turns off. I also shorted one driver and found my DVM reading amperage but no light, checked it again then re-soldered everything from the last step and all has been well for the last few weeks. It appears no damage was done. I would have tossed the driver had I not developed this method.

I have several of these heat sinks kicking around from my PC building days and would be glad to send one to you if you want to do the same. Sorry, no XM-Ls left over.


here's my work...

same board, different pic...

On the back side I don't see any possible issues. The spring is soldered on center, no overflow. And the negative ring was soldered to the pill, again no overflow onto other parts of the board.

On a side note, I had a P60 drop-in with an XM-L pulling 1.7A. Then I put in an XR-E LED with the same driver & battery and now it pulls 1.0A. did multiple tests. What is going on?

Matt, unless your using a DC power supply, I'm not sure how your applying voltage to test it? I don't have a power supply, just the DMM.

You’ve got PPtk’s ear so I’d wait for his ideas. The LED + solder looks good to me but not sure about LED -. And did you only solder the driver to the pill in one spot? I find that the hardest thing about building P60s.

No, I've been soldering at multiple places to make it better grounding, well in case a solder point breaks off. I haven't been potting these yet.

Hmm… I don’t see anything there that would justify a completely dead driver.

When you turn it on, what happens? Anything? Is it just completely dead, or do you get single mode operation?

are you sure your LED’s aren’t what are actually dying?

When you try turning it on, if you leave it on for 20 seconds, does the battery get warm (would indicate a short or reverse polarity somewhere)?


yeah nothing happens when I hit the switch. Except frustration :-)

I'll try another LED. Though I think I already tried more than one.

And I'm going to do the other things you said. Can you also comment on this because I think I'm losing my mind here...


MRTdiver. You sound like your having as much luck as I used to have with these things. I have learnt to do one step at a time and test after each step. The wires for the LED go on first. It is then tested by just holding the wires onto the star with a battery hooked up and continue like that after each step. If I then have a problem I know where to look. The last one I did mucked up and in frustration left it for the next day to sort out. Next day it mysteriously had fixed itself and has not missed a beat. Good luck.

You have a good set up there itinifni for testing.

Well I changed the LED like PPtk said. Apparently I put about 4/5 drivers on that same LED.

Now I'm back in business. measured 2.68A at the tailcap with Nanjg 105C driver :-)

I have no idea what's wrong with that LED I took off. A new XP-G2 mounted on a star. This is the one from IOS. I don't know, I thought LEDs weren't really a fail point.

And yes I connected it positive wire to pos. on the star. So it's not that.

Glad to hear you’re back in business…

As for the LED - my bet is that one of those 4/5 drivers had been broken or mis-wired, and you sent an XP-G2 into direct drive from a Li-Ion. The XP-G(2) is not an XM-L; it can not survive the current that will be slammed through it in Direct Drive. It would die almost instantly from that amount of current.

For testing raw LED’s, I strongly suggest everyone get a 100 Ohm Through Hole Resistor. A 100 Ohm resistor provides a good safe current limit to any of the LEDs that we use and you can then use an 18650 to test with.

Wire From 18650+ to Resistor, From other side of Resistor to LED+ and from LED- to 18650- and you’ll light it up enough to test without it being blindingly bright or dangerously hot. Over the years, I’ve killed far more LED’s than I have drivers - usually do to inadaquete heatsinking… Lighting up an XM-L on a star at 3 amps, for instance, will kill it in about 20-30 seconds if the star isn’t heatsunk to anything.

Good luck with your modding!

Couple possabilities…

1) Damaged a few of the AMC7135’s. If you kill some of them, often times the rest will still function and you’ll get reduced output
B) Damaged XR-E. Not all that likely seeing as it ‘kind of’ works. LEDs are usually a go/no-go device.
3) Wiring from Driver to LED too small. Small guage wire has higher resistance and will drop voltage preventing the battery from delivering the current you expect
D) Something else is high resistance… Poor solder joint from driver to pill, poor connection of pill to flashlight tube, poor tail-spring, etc, etc, etc.
5) XR-E you have there has an usually high Vf, meaning that you would need more volts than your battery can provide in order to drive it harder than 1A

If you really want to diagnose without much equipment, the first thing to do is try a different emitter and see if the driver is still working as expected…


I know what happened now with the simple LED swap (XM-L to XR-E) and the drop in tail cap current. I also CHANGED the BATTERY, resorting to some older/weaker 18650s that I pulled from some recycled battery packs. They don't even have a capacity (mAh) reading on them.

Anyways when I used those vs. my Panasonic 3400mAh. I get totally different tailcap amp readings...

Panasonic 3400mAh vs. recovered Panasonic CGR18650C (I think: 2150mAh capacity - BLUE cells below)

XR-E (with KD 6x7135 V2 2280mA driver): 1.4A vs. 0.5A now I can't explain why it's not reading 2.28A

XP-G2 (w/nailbender's 1.7A driver): 1.7A vs. 0.7A perfect 1.7 to 1.7A reading

XP-G2 (w/ Nanjg 2.8A driver): 2.2A vs. 0.9A now I can't explain why it's not reading 2.8A

I guess that I may be damaging the ICs. Been using 22 gauge wire, so it's not poor wire size.

1. Get rid of the Ultrafire cell.

2. Those Panasonic cells have suffered, I wouldnt use them anymore.

3. The voltage of your Panasonic 3400mAh drops too much to power an XRE with 2.8A. Actually 2.2A is a lot for an XRE.

4. To make sure your driver works, get an XML and an IMR cell (or something like the Panasonic CGR18650CH). That combination should read 2.8A dead-on.