The unprotected seems to fit ok (in fact the light will flash on a little when I first start tightening the head down). Once tightened…nothing. I thought it might be the spring on the head was not making good contact with the shorter unprotected cell but that doesnt seem to be the case (unless its doing something funny as it gets tighter). The unprotected cells are charged (~4V and work fine in a P60 clone).
Is the unprotected cell significantly shorter than your protected one? I know you said that the light will actually flash upon tightening the head down, implying some intermittent contact is being made, but it’s prudent to rule out cell length. Does the light work when you remove the tailcap and administer the aluminum foil test (making contact between Batt. - and bare aluminum threads using a strip of foil)?
Edit: I haven’t seen you around the forums here yet, so welcome to BLF!
I tried the foil test…nothing. Checked with a DVM - steady 0 V at the tailcap.
I dont have a magnet to try with. Maybe I should pick up a few since I ended up with these unprotected cells by accident from fasttech.
Just now, by kind of jiggling the head as I screwed it onto the light, I got it to stay on for a while. Once I turned off the light it wouldnt come back on until I loosened the head and tried again.
Anyone have a recommendation for a good c8. I use this meritline one on my bike and it works pretty good for the price but I wouldnt mind something nicer (and something that coud use my unprotected cells).
With the unprotected cell installed, shake the a back and forth. Can you hear the battery moving around? This might indicate a contact problem.
The pictures show a nice long driver spring, so I doubt it’s that. Can you check to make sure that spring is there?
Yea I think the magnet might be the best idea. It is a flat top but seems to make the best contact when it is only lightly screwed down (maybe 1 turn or 2). I think the springs are plenty long but the issue is how the spring in the head deforms over the flat top as I tighten it.
Thanks for the ideas. I will update if I ever get some magnets. If not, I will just buy a couple more protected cells and use the unprotected ones elsewhere.
I did that (buy a couple more magnets). It seems that as long as you’re (we’re) messing around with flashlights, they’re nice to have around. I originally ordered just a couple from lighthound, then ended up getting more and more, then a bunch from Fasttech.
Plus they are kind of fun to show to people (hold a couple of the larger ones a few inches apart, then release one :)…).
It could be a loose retaining ring in the tailcap. The longer protected cells may be exerting enough pressure on the tailcap to make a connection, while the shorter ones don’t. I noticed you said it would flicker a bit when you shook it. Try tightening down the tailcap retaining ring with a needle nose pliars. Some retaining rings tighten counter clockwise.
