Thats a sign of a depleted or well-used NiMH… that can’t deliver enough voltage under heavy load. On my lights there is a slight but noticeable difference between turbo and my next highest level. Its most visible on a ceiling bounce or outdoors. But then again, it needs a fully charged / healthy eneloop to achieve this.
My UT01 just arrived, and it’s very impressive for 1xAA. I really like the mode selection and it’s enormously bright on high even with just a AA. I ordered a 14500, so I’ll let you guys know how that works out when it arrives.
Please try briding the end and switching it on.
As your NiMH works it should light up.
If it does bend a wire e.g. from a paperclip to a ring bending around the battery. Put that ring in the cap.
Use a copper paperclip (lower resistance) steel works too
I could try briding the cell contacts and the spring I suppose. I will try it tonight.
But the cells charged OK on the charger (indicator light changed when fully charged) so it seems like it shouldn’t have a coating on or anything. It +looks +clean. I have two cells and neither works.
The fact that NiMH cells work means the flashlight contacts should be clean?
The Xtar is sold as an AA-sized protected 14500. It is a little longer than AA but only marginally.
I hesitate to buy unprotected 14500’s could be more money wasted.
"This is what I am worried about. The Xtar protected 14500 cell IS marginally longer than the NiMH cell that DOES work. I have tried screwing the tail cap down as hard as I dare. To me, it seems to screw all the way down. Anyhow, there is no switch in the tail cap. Is it not just a spring contact, or is there more to it than that?"
Look inside your tailcap. See that gold colored ring at the base? Now look at the end of the battery tube. See that silver shiny ring at its end? Those two surfaces have to touch to complete circuit.
You may think it's screwed all the way down, but with a longer cell the tailcap contact ring may NOT be making complete contact with the silver shiny battery tube contact. This is because a battery that is too long for the tube will not permit the tailcap ring to contact the tubes shiny ring.
The failure to work with protected 14500’s was reported quite a while back and is a known feature (I wouldn’t even call it a defect since the light was built that way).
The threads are anodized black which is non-conductive.
When I started in this hobby I started with protected batteries but came to learn that you really don’t need protected batteries in single cell flashlights. In real life when the battery gets low and the light gets dim you change it before it is fully depleted. I no longer use protected batteries in my multi cell lights either. I do date my batteries when I buy them and keep sets together for my multi battery lights.
I have two unprotected Efest 14500 batteries charged and waiting for my Utorch to come in.
Thanks everyone, I had a look at it last night and I realise what you are on about. The only point of contact between the tube and the tailcap contact is the unanodised end surface of the tube. If the battery is a fraction too long it won’t make contact.
So at this point in the story, the working hypothesis is that Xtar Protected 14500 cells are in fact too long.
Possibly I could get it to work with a ring of copper wire or paperclip made into a ring to fit between the battery tube and the tailcap contact. Or ideally a copper or brass washer of the right size, if I could find one, I guess.
Quote kzb:
Possibly I could get it to work with a ring of copper wire or paperclip made into a ring to fit between the battery tube and the tailcap contact. Or ideally a copper or brass washer of the right size, if I could find one, I guess.
I never use protected in a single AA/14500 setup. And I really don’t see a need to. So, problem solved. I knew I’d use non-protected before I even ordered UT01. Simple.