Solarforce p60 drop-in poor electrical contact.

I recently made my first p60 drop-in with an L2p, S6 tailcap, 2.8A AMC 7135 driver, and an XM-L.
It started out pretty rough if you look through my thread, but I got it all sorted out in the end (so I thought).

Now, I'm having a weird problem, it seems like there's some weak contacts somewhere. Sometimes, the light will flicker a bit, if I shake it, or smack it a little, it usually stops. It hits the low voltage warning absurdly early, but if I smack it around a little, I can keep running on high for quite a while longer. Sometimes, it doesn't turn on unless I wiggle it around. When it won't hold high at all without having to wiggle it all the time, the batteries come out at about 3.8 - 4.0 v open circuit. My hobby charger usually only puts <800 mAh back in, and they hold ~4.1 - 4.15 v that they come off at. I'm pretty sure there's some resistance somewhere causing a voltage drop, probably a lose contact.


Ruling some things out:
I'm using aluminum foil and copper tape from illumination supply. I'm assuming that the adhesive is conductive. It's stuffed so tightly I need pliers to take it out, so that seems quite solid.

The batteries are in tight enough to rub a pretty noticeable circle on the bottom of my batteries, and the top of one of them has a very slight indent. It doesn't turn off if I shake it forward and back.

I've used the pill itself outside of the host a bit, and it's worked perfectly. There are three solid looking solder joints from the pill to the driver board's negative contact rim. Wires to the LED look solid. The pill (copper) is screwed into the reflector pretty well it seems, and the threads were cleaned with alcohol prior to screwing them in. I hope there's no oxidization there and I don't want to check just yet because it's pretty difficult to take it out. I didn't see any the past few times I've taken it out.

I have a Redilast 2900mAh, purchased recently and a blue wrapper Solarforce protected 2400mAh, also purchased recently. Initially, both cells seemed fine, charging up to 2000mAh - 2500mAh+ on my hobby charger after hitting the low-voltage warning. Only about ten cycles each, never stored at full charge, spent most of their life in my flashlight or in the refrigerator, never discharged too low.

Removed the original lube using a cotton balls and alcohol and relubed with krytox three times (cleaning off the old lube each time). I've always thought that dielectric lube is fine for aluminum contacts. Honestly, if it were anything, I'd have to guess tailcap contact somehow, I have no idea how. It looks okay to me, if anyone can see anything I'm doing wrong here... The flashlight worked fine at first, so I thought it was the contacts oxidizing or something, but lubing with krytox doesn't seem to have changed anything. I've tested using a wire instead of the tailcap, and though I haven't tested very much, I haven't experienced this problem using a wire (though it was a few weeks ago, before this problem had been a problem. I tested like this when I was troubleshooting because the pill wasn't stuffed all the way in, which gave similar symptoms).

There are pictures in the thread linked above.
Thanks for helping.

Does the L2P require the use of the negative contact spring (the bigger spring) too?

I have an L2 that has slight flickering when I don't use the large spring too, but then again mine's not packed tight with foil, I can still manage to pull it out with just a little extra effort.

Also, did you just press-fit the driver, or did you actually solder the negative ring to the copper heatsink?

Edit: ok, after seeing that the drop-in has been pretty much press-fitted to the host, I doubt that the issue would be the big spring. And I see where you did solder the driver to the copper pill.

Best of luck, I'm not really sure what's going on. Have you done any modifications to the tailcap?

Is your L2P a 2011 version or the original version? The original one has a longer battery tube that has been known to cause contact issues.

With mine ( original version), I can change modes on a multi-mode drop-in just by smacking it.

Uhm... I have no idea. I ordered it from solarforce-sales around august.
How can I check, and what's there to do about it?

No changes to the s6 tailcap.

I'd say you most likely have the new 2011 version, which has a slightly shorter battery tube to resolve the issue I mentioned.

with teh sort spring of the 8x7135 driver there will be leght issues with any body

you will need a spacer around 10mm long between battery butt and tailcap spring to work...

kosPap said:

with teh sort spring of the 8x7135 driver there will be leght issues with any body

you will need a spacer around 10mm long between battery butt and tailcap spring to work...

Click to expand...

Not completely true! I have no problem running my NANJG 8x7135 modded drop-ins with a FM 18350 body and any cell I've stuck in there. Having a short tailcap with a long spring helps too...

So...?
I don't think it's a loose battery problem. It's not shaking it in the direction of the battery that can make it work on high, it's hitting the sides of it.
As I said, my batteries have pretty prominent marks on the back where they rubbed against the spring.

After a lot of reading, it looks like Krytox is not for bare aluminum threads. It works great for o-rings and anodized threads though.
I've read from some people that Nyogel works well on aluminum threads, but I've read that it also blackens somewhat quickly. IMO that is not working too well.

Does anyone have suggestions for lubricant on bare aluminum threads?

I checked intermittently, running down about a whole battery's worth using a wire instead of the tailcap. No problems at all.
It's working well about 60% of the time after getting the krytox off and applying a petroleum distillate motor oil. I took out the o-rings first. Not much black grit building up.

On the other hand, I've noticed moisture on the inside of the lens whenever I leave it on high for a while even after leaving it in a bunch of rice for a day. I have no idea why, but I suspect it might be the oil.

I've read through a ton of the comprehensive grease and lube thread, and a lot of other random threads that I found by searching. Still don't have an answer for lubricant.

Hmm - I had a similar but more extreme version of what yer talking about but it would happen in my L2P as well as my C2.
At first it was an occasional dimming even on full batts. Then one day after being off for 3days or so it barely turned on.
Super dim. This is a 1 mode dual xpg 2.8a drop. SUPER bright usually.


I thought it was because I wasn't using an outer spring (in the C2)
Then I thought it might be too much AS-5 smeared all over the reflector and some was in the threads.

I cleaned everything out with alcohol and tried again. Nothing. Not even dim. Then while I was doing something on my computer it flickered for a min and then went to full brigtness.
There was fog on the inside of the UCL too.
I turned it off. Back on a few min later and was about 50%.

Anyways I think it was the driver so I sent it in for repair by Nailbender.

He has to drill it out as it was potted.

I knew it wasn't the hosts or batts as I had others to try for elimination.
All of my other drops work fine in both hosts.

Nanjg driver I believe.

Keep us posted!

Perhaps the switch is to blame, if it runs fine with a wire shunt.

Yes, that's a possibility, along with poor contact. I think that poor contact is unlikely though. Should I contact Solarforce-sales?
I still need a lube for aluminum threads regardless.

I tested the switch with my cheap analog multimeter's resistivity test when my light wasn't working, and there might have been some fluctuation, I'm not sure if it was the probes slipping or the switch failing. It checked out fine after that little incident, and likewise worked perfectly in my light.
I also screwed and unscrewed my tailcap while it was on at this time; no fluctuation in the light's output, so I'm guessing the contact is okay. I'll keep an eye out to see if I can catch the switch misbehaving. Then I'll contact solarforce-sales.

How should I contact Solareforce-sales anyway? I'd prefer no long distance calling...

I use Phil Wood waterproof grease on my lights -2 L2P and 1 C2 with no problems. I use it sparingly.
It's bearing grease for bikes but seems to work fine.
I've even used Slick Honey on my Quark mini123. Its a seal grease.
For rubber seals not made from seals

I doubt it's yer grease/lube.

Have u tried a different dropin?

I don't think it's the dropin, again, it works fine outside of the host, and has always worked fine by using a wire instead of the switch.
Appreciate the lube recommendations...

EDIT: Ah hah! My flashlight started flickering and turning off, so I took off the switch and tested the resistivity with my multimeter. The needle wiggled a bit, and wasn't making it to full conductivity. Note that I am putting the test leads on the retaining ring and the tailspring, and not the actual switch. I have yet to see it fluctuate at the actual switch, so it might be the retaining ring's thread contact.

EDIT... It wasn't working with the wire instead of the tailcap. I'm very confused now.

sand negative end of the body, where it contacts the metal ring in the switch

Make sure that the metal ring in the switch is screwed in all the way, and correctly. If you have a good tool to remove this ring with, I'd recommend actually completely disassembling the switch and reassembling it. There is a tension ring, looks like a stamped metal ring that has a few bends in it, along with spacer, switch mounted on switch board, boot, and the metal ring. Make sure all metal parts are relativelyclean, then reassemble.

As far as your edit about it not working with the wire shunt bypassing the switch, well, I'm pretty confused too....

Too bad u don't have another drop to try.

This does sound very similar to my problem which was the driver.

psychbeat said:

Too bad u don't have another drop to try.

This does sound very similar to my problem which was the driver.

Click to expand...

Indeed, I'll post back when I get a new driver here. It could be a while; it's from kd.

Okay I've finally figured out the problem.
While this thread was being dead, I was up to some testing.

I did manage to pry out the dropin; there are a lot of deep gouges at the top of the reflector but the reflector itself is fine. I was going to just change out the driver, but then I saw a lot of tarnished copper. I have pictures if anyone is interested, but the pill was terribly oxidized. It hardly worked directly touching a wire from the battery negative to the aluminum reflector.

I cleaned up the copper with vinegar and salt, which shined it right up, and it worked perfectly. I rewrapped it in foil and stuffed it back in (not too tightly, easy to remove). I noticed a few weeks later that I was experiencing the same problems. Opened it up, and it was tarnished again.

I tried this a few times, making sure that the pill was dry and the humidity was low, but it tarnished quickly every time. Within about three weeks, it wouldn't be able to turn the light on at anything other than low when the battery had an open circuit voltage of about 3.75v.

This time, I've recleaned the copper and reflector, but this time I put a few blobs of solder connecting the reflector and the copper pill, so I hope that should keep the connection strong. I just checked and it's already starting to tarnish a bit, but it's still working great.

It's looking good. I think this problem is solved. Thanks for reading/helping.

and we should thank you for sharing your experience...good job1