Cell extender problem

I recently picked up a 123 cell extender for my Surefire L4, but I'm having problems getting a good ground connection between the extender and the L4 body with the stock O-ring in place. If I take the ring off, then everything is fine and dandy. Has anyone else had this problem and found a solution other than removing the O-ring. It's going to need all the water resistance it can get.

I believe that the problem that you are having is due to the fact that the juice from the batts won't flow (conduct) through the anodizing. You will need to provide an electrical path. You may be able to remove the anodizing from the threads of both the L4 body and the extender.

I usually use lye to remove anodizing, but I don't know how you'd remove the anodizing from the threads.

That's what I was thinking at first as I had seen other people that had that problem, however it works fine when I only screw the extender down part way. There is plenty of HA coating there yet it still works. As soon as I get to where the O-ring is, the light cuts out. But the more I look at it the more perplexed I get. It looks like there are only enough threads on the extender to make contact with the o-ring and maybe a few threads on the body when it completely tightened down. I'm kinda wondering if there was an earlier version of the DSpeck extender (which is what I might have) that was intended for a different body style with a different thread pattern.

If it is the anodizing in the threads, you could use a dremel with a wire brush to get rid of it.

Why would one use a cell extender on a L4?
Isn't that like direct drive, or only little resistance?

I found a solution that let me keep my L4 in mint condition. I cut and formed a piece of paper clip into a ring that snapped inside the bottom of extender. It made good contact with the upper part of the L4 body and still allows the o-ring to function so it's water resistant.

And yes pyro 3 cells would run the L4 head in DD and unless I had a high Vf lux, it would not be too happy about it. i.e. shorter than average life span. The extender would be used with a KL1 head or in my case with an E2C and a spare P90 lamp assembly for some throw which the L4 really lacks.

jbev, I had to do something similar with the A19 extender and the nitrolon G2.

Those E2Cs are great, they open up all sorts of possibilities.