Infinity Ultra Mystery

Turned on my Infinity Ultra and it was dead. Tossed the old alkaline batt and popped in a used lithium, the light worked. Decided to try another alkaline but no go. Ok, it might have been an old dead batt laying around. Took the alk out of my operational yellow Infinity (talk about dim) and put it in the Ultra and still no go. Took the original Ultra batt out of garbage and put it in the regular Infinity and it worked fine. Tried it in Ultra again, still no go. /ubbthreads/images/graemlins/icon3.gif

Figured I might be having continuity problems that only the extra oomph of the lithium could get thru. Used a paper towel to clean the threads and inside the body. Lots of dark grey "grease" came out of the threads but it still didn't work. Conviced that I was on the right track I worked several minutes more on cleaning the threads and body. This time it worked.

Wonder if the dark grey stuff I removed was machine oil from manufacturing. I had noticed that the batts coming out of the Ultra were dirtied by it as well. Anyone have a similar experience?

The black is probably aluminum oxide mixed into the grease. Al-Oxide is very good insulator. Also, check down inside the base of tube--you could have oxide built up there too. It may not be visable as Al-Oxide is clear when covering the base metal--you can use a pencil eraser to buff the contact face.

My CMG Ultra is dead flat on the bottom except for a small button left from machining. If you continue to have problems with a connection at the flat base, you might try to put a split or star stainless steel (if you can get it)washer (not too aggressive) in the base. Point contacts make better connections--but could increase wear. I have not tried this myself as I have yet to see a problem.

-Bill

Apart from cleaning the contacts, could it also be the used batts that you were trying out? The Ultra is rated to be brighter (2x) than the regular infinity, thus could it also be possible that it'll require more juice out of a batt to power it, compared to a Infinity?

You can probably greatly improve the output of your yellow Infinity by cleaning the anode contact with an abrasive.

AA's only cost 30 cents each, so why keep old ones - those flashlights need all the help they can get - from either new batteries or rechargeables.

BB - Good thinking.
Stanley - Ultimately the original alk battery worked, so the issue really was the insulative value of the grease which I removed. Yes, the Ultra does draw more amps than the original, that's why it's brighter and has shorter runtime.
LightScene - True, batts are cheap, but I'm even cheaper.