Fenix tailcaps leaking current?, check yours!

Try to check your Fenix tailcaps. I had 4 (L1D, L2D, P2D and P3D,all Cree versions) of them and have noticed that there was a resistance between the tailcap body and the spring contact. Measured resistance is not the same but, some went as low as 50K ohm. This translates to 0.12mA of leakage current for a P3D. This means that your fresh CR123's would just drain out in less than a year without using it.

After taking them apart, it was traced that the leakage was caused by the rubber o-ring. The more you tighten the aluminum retaining ring, the lower is the resistance. I 1st suspected it was moisture accumulation on the rubber so, I thoroughly cleaned them with water or alcohol but, leakage still persists. I believe this problem is not only on what I have since I already have 4 of them and all have similar problems. Although, for lower battery voltages like the L1D, this leakage will become so negligible, it still wouldn't feel right knowing something is draining your battery power.

I don't know Fenix quality control engineers were aware about this. What I did was that I wrapped teflon tape around the o-ring to fix the problem.

Do you think it's the O ring or the lube ?

It seems like Fenix threads are always dirty from use, maybe some aluminum mixes with the O ring lubes. Could be it migrates all over that switch, not just the O ring.

LOL, just some wild speculation, so don't everyone go nuts on me

Howdy Glowman,
Interesting observation. It seems to me that Fenix has proved to be very responsive to customer input, so I would think it would be beneficial to drop them an e-mail and let them know of your findings and see if it is something that they are aware of. That's how good products become better products.

It was the o-ring. I measured the resistance of the o-ring with the slim test leads of the meter, it registered more or less 500K ohms. This would become greater when you place it on the assembly since there will be more area of contact to the o-ring. BTW, I made sure the o-ring is completely dry and lube free. I noticed this problem before I added additional lube. Lube i used is pure silicon grease with no measurable resistance between test leads dipped in grease and just 1/8 inch apart.

I believe I'm not alone with this so, anyone noticed this, pls. post.

I emailed Fenix regarding this issue and referenced this thread. Fenix service responded immediately:

"Yes, we have resolved it. In fact, there is only a small batch tail cap has this problem.
Thank you attention!"

hmm.... vaguely disturbing

No problem with my L2T tailcap. I'll have to try tonight with my L2D tailcap.

My L2T forward clickie tail cap does it, but only once you tighten the locking ring, I swapped the o-ring for the one from the reverse clickie and it's all OK now :shrug: :shrug:

My P3D RB100 has the same problem. About month ago I contacted Fenix Store about this problem and they sent other o-rings for my flashlight, but not this big rubber o-ring... That time I believed that I am the only one who has this problem.

So what's the easiest way to check for this, and what equipment do you need?

Because I really don't have any.

Can you post some photos? I assume you're talking about the rubber ring around the tail cap spring that sits in the aluminum locking ring?

mchlwise said:

So what's the easiest way to check for this, and what equipment do you need?

Because I really don't have any.

Click to expand...

Hi, with an multimeter set a ohms. Take a read between spring and retaining ring inside tailcap.

Make sure your tailcap switch is OFF.

I took a read on my P2CDE natural tailcap. All is OK for me. Infinite resistance :thumbsup:

gerry45 said:

Hi, with an multimeter set a ohms. Take a read between spring and retaining ring inside tailcap.

Make sure your tailcap switch is OFF.

I took a read on my P2CDE natural tailcap. All is OK for me. Infinite resistance :thumbsup:

Click to expand...

Thanks.

Guess I'ma have to get a multimeter.

Thanks for posting this Glowman.

Just tested 4 fenix clicky caps: both my old LxT caps and original L1D show infinite resistance (whew), but my Q2-edition P2D shows ~2M ohms resistance. Cleaning that o-ring also made no difference.

That current drain shouldn't be too bad (i.e. 0.0015mA with one CR123A) - but I always store my lights with the tailcap locked-out anyway, so there should be no problem. But I'm glad you brought this to our attention.

I always recommend storing lights with the tailcap locked out when not in use (especially for CR123A based lights).

FYI, for those wanting to test their tailcaps, even the cheapo basic DMM at DX should work fine for this.

gerry45 said:

Hi, with an multimeter set a ohms. Take a read between spring and retaining ring inside tailcap. Make sure your tailcap switch is OFF.

Click to expand...

I had never done this kind of test before, so I found it helpful to turn the switch on, just to see exactly where I should be measuring... which on my L2D CE is between the spring and the retaining ring (just as gerry45 posted), which with the switch on reads a completed circuit (imagine that), but shows infinite resistance with the switch off.

I love learning new things. I'm also glad to see that there is no problem with my light. Thanks to everybody for the very useful information.

I tested the caps on all my lights with tail cap switches (P2D-CE, P2D-CE, P2D-CE Q2 SE, L2D-CE, P3D-CE, P3D-RB100, L1T V2, L2T V2, LM303, LM301, MRV, M1, L1, L1, M3, C2) and none of them showed anything but infinite resistance with the switch in the off position.

Ok my P3D does it too. What is the fix for this problem?

Thanks

selfbuilt said:

.FYI, for those wanting to test their tailcaps, even the cheapo basic DMM at DX should work fine for this.

Click to expand...

Another FYI - Those cheapo basic DMMs available at Harbor Freight Tools should also work fine for checking resistance in the tailcaps.

Alot of times, they are on sale for $2.99 to $3.99.

I've compared these HF cheapies to a better auto-ranging meter, and they were surprisingly accurate. :thinking:

lumenal said:

Another FYI - Those cheapo basic DMMs available at Harbor Freight Tools should also work fine for checking resistance in the tailcaps.

Alot of times, they are on sale for $2.99 to $3.99.

I've compared these HF cheapies to a better auto-ranging meter, and they were surprisingly accurate. :thinking:

Click to expand...

Yeah, I paid $5 for mine...

Digital MultiMeter for $5....

UnknownVT said:

Yeah, I paid $5 for mine...

Digital MultiMeter for $5....

Click to expand...

Thanks!

I've got a Harbor Freight just down the street! :twothumbs