6P tail caps don't like 18650s *Update*

Update post 15

I've got a bored 6P that keeps having the same problems with 18650s. When using any drop-in it has to be pushed down completely, really hard, or it flickers.

When using two primaries, you have a little lee way when you press down. With mine, it's either on or off, there is no flickering.

With 18650s, it's either on, flickering, dim and flickering, or off.

Sigh, I've taken this thing apart and cleaned multiple times and tried another spring but it doesn't work.

Same results with different 6P tail caps. I think it might have something to do with primaries being slightly longer.

Any ideas? JustinCase gave me a few pointers, but I think I'm 99% confident I've narrowed it down to my tail caps hating my batteries :thinking:

Re: 6P tail caps don't like 18650s

Yeah, I know what you are talking about.

The little extra length with **670 variety batteries make a lot better/easier contact with some Z41's.

Are you using a Z41 or Z59?

Re: 6P tail caps don't like 18650s

Z41.

It kills me because it has to be pushed just perfect to make perfect contact. With primaries, you just push and be done.

If the retaining lip was longer, or if I could find something to put between the 18650 and it I'm curious if anything will change.

I tried a GITD ring but I think it's too squishy

Re: 6P tail caps don't like 18650s

I find that I just have to twist is a little closer to constant on, then it seems to get better contact.

Maybe some form of plate on the end of the battery?? :thinking:

Are you using a Malkoff, or your Nailbender?

Re: 6P tail caps don't like 18650s

DimeRazorback said:

I find that I just have to twist is a little closer to constant on, then it seems to get better contact.

Maybe some form of plate on the end of the battery?? :thinking:

Are you using a Malkoff, or your Nailbender?

Click to expand...

NB. I usually keep it really close so to constant so I can easily twist it, but nothing seems to be working.

Re: 6P tail caps don't like 18650s

I haven't had that problem with my DIY modules in my 6p. Some modules have a very short spring on the +B end, for those I just stretch the spring a little.

:thinking:

Re: 6P tail caps don't like 18650s

As kramer5150 mentions, I would look at the Batt+ end, not the tail spring (Batt-) end. The Z41 spring certainly is long enough and has a narrow enough conical tip to make reliable contact to an 18650.

I would look at the top end because most likely the boring leaves essentially a retaining rim so that the 18650 cell can move upward only so far. If the drop-in's center spring doesn't protrude down far enough, you'll get unreliable continuity. Even screwing down the tailcap won't push the cell upward far enough because the retaining rim holds back the cell.

What specific brand/version of 18650s are you using? For example, the new AW18650 2600mAh cells have a fairly flat top that doesn't extend much past the plastic wrapper. I've also run into this with Accupower NiMH cells in a D Mag. Other cells sometimes have a slightly undersized (in both diameter and height) top button that doesn't make good contact with the conical center spring of the drop-in. I've seen this for AW17670 cells in an SF U2A.

Re: 6P tail caps don't like 18650s

kramer5150 said:

I haven't had that problem with my DIY modules in my 6p. Some modules have a very short spring on the +B end, for those I just stretch the spring a little.

:thinking:

Click to expand...

I might try that if I can do it without breaking the spring off the driver.

I hope Dave doesn't read this.

Re: 6P tail caps don't like 18650s

At least for your typical Chinese drop-in, the center spring is soldered to the center anode pad. I would hold the bottom coil of the spring to relieve the solder points of tensile stresses (this should also relieve the solder blobs that ground the driver to the pill of applies stresses). Then pull carefully to stretch the spring.

Another lengthening trick is to solder a small spacer disk to the top of the conical center spring.

Re: 6P tail caps don't like 18650s

Justin Case said:

[...] Even screwing down the tailcap won't push the cell upward far enough because the retaining rim holds back the cell.

Click to expand...

This sounds pretty reasonable to me. Z41's are on all of my lights that will take them, and I have never had an issue on the (neg) tailcap end. However, I once had issues with 2x AA in a very tight (diameter-wise) spacer in my SF C3, I would get unreliable contact with the Malkoff (pos) spring because the cells were resisting forward travel even under maximum tailcap pressure.


Edit: I've measured cell depths (at the tailcap end) with my lights that have Z41's, and the 'deepest' one is my SolarForce L2 mini with 1xCR123. It's about 0.10" deeper than my 6P / AW18650 flat-top, and the SF Z41 tailcap has never failed to function flawlessly on it - even though it functions at about a half-turn deeper than my other Z41-tailcap lights.

Re: 6P tail caps don't like 18650s

I'll try that as soon as I fix my tail cap. I took it apart to clean it and now when I line the two notches up it turns on. So between the time the notches are lined up and fully tightened, it's turned on.

I've got to stop taking things apart. Something doesn't make sense though, I mean damn, there's only about 4 parts to put back correctly. I think I might have messed up the springs shape

Re: 6P tail caps don't like 18650s

I use a Z41 on a Solarforce L2 with Trustfire and AW 18650 button top cells without any problems at all.

Re: 6P tail caps don't like 18650s

I'm starting to think my 6P in particular isn't cooperating.

Re: 6P tail caps don't like 18650s

I had the same problem with a Dereelight drop in and the P60L with a 17670 and my 6PL. With the Dereelight 3SD it was particularly irritating as it changed modes. I've since had it bored and had electronguru install a mcclickie in the stock tailcap and with an 18650 it works like a champ now!

I was not particularly wed to the twisty anyway since most of my lights are clickies as it is so this was a big plus upgrade for me. May not be how you want to solve it but the mcclickie upgrade works really nicely.

So after taking the tail cap apart to clean I ran into some problems. The light was turning on constant when the two notches were lined up. After taking it apart 20 more times it was coming on even before they were lined up. Which resulted in barely any space for momentary on.

After 5 hours of ripping my hair out it hit me. So here is some advice that is crucial to anyone taking a Z41 apart.

After you pull the spring out, you have to pull the piece out that actually makes contact with the body, a shiny aluminum piece (simple terms ).

Under this is a PLASTIC retaining ring. It's easy to take out. I ran really hot water in it for about 30 seconds. 30 seconds of burning my fingers.

Well, when I went to put it back it I didn't even think of the damage I was going to the PLASTIC retaining ring. You will damage it, but it won't affect the light, unless you fail to fix it.

The needle nose pliers dug into the side of the grooves in it. This lifted part of the plastic up beyond the rest of the flat surface. This causes the aluminum piece that turns the light on to be higher than it's supposed to be. So no matter how tight everything is, it's still abnormal.

I took a metal file and filed it all back down to perfect flatness. Then I took my knife and corrected the inside, which is hard to do. Making sure everything was flat again.

So, if you take it apart, flatten out the plastic retaining ring. It will cause you lots of grief. Lots and lots of grief Plus your fiance will start throwing remotes at you to pay her attention.

man Search....you have more patience than me! I would have been chewing on the business end of my gun!!!

Search, I had that same issue putting a G2 tailcap together. Thanks for the comprehensive report. The plastic retainer is incredibly soft, and the glue they use does not like to give up. Glad you got your fixed.

I was having flickering/intermittent functionality of my 6P, until I stuck some 1/16" magnets on the ends of the cell. That solved the problem entirely.

Maybe get someone to make some aluminum spacers that have some heatshrink wrapping around them (to prevent accidental turn-on), to help eliminate that problem.

~Brian

bstrickler said:

I was having flickering/intermittent functionality of my 6P, until I stuck some 1/16" magnets on the ends of the cell. That solved the problem entirely.

Maybe get someone to make some aluminum spacers that have some heatshrink wrapping around them (to prevent accidental turn-on), to help eliminate that problem. ~Brian

Click to expand...

Soon I'll have a similar problem. I've just received the parts to build a FiveMega 3x18650 body. But I won't be using three 18650 cells; I'll be using four AA cells. I've already found a suitable copper "inner tube" so the batteries won't rattle. But four AA cells are too short. If I use a spacer--be it a magnet or something else--I must make sure I don't lose it, mislay it, or leave it behind each time I charge the batteries.

What I'll probably do is cut the copper inner tube long and plug one end with a socket from a socket wrench.

Paul_in_Maryland said:

Soon I'll have a similar problem. I've just received the parts to build a FiveMega 3x18650 body. But I won't be using three 18650 cells; I'll be using four AA cells. I've already found a suitable copper "inner tube" so the batteries won't rattle. But four AA cells are too short. If I use a spacer--be it a magnet or something else--I must make sure I don't lose it, mislay it, or leave it behind each time I charge the batteries.

What I'll probably do is cut the copper inner tube long and plug one end with a socket from a socket wrench.

Click to expand...

What I do when charging my 18650 for my 6P, is I stick the magnet to the side of the battery. That keeps me from forgetting about the magnets.

~Brian