Wierd issue with SC51

I carry my SC51 every day, and it's a wonderful light, perfect for my needs. I noticed something funny about it, though, and I was wondering if anyone here could offer some theories as to why this happens.

When I first got the SC51 I put a straight-from-package eneloop into it and everything seemed fine. Later I put in a fully-charged eneloop, and I couldn't see any difference at all between the default H1 and H2 settings. I assumed this must be because the battery was providing too much voltage or current, and that the modes would return after the battery wore down a bit. After a few minutes of use the modes returned.

Now, every once in a while, the light 'forgets' some of its modes. For example, last night I was unable to switch between L1 and L2 by the usual double-clicking; the light was stuck in L2. I tried turning the light on an off, cycling through L, M, and H, going through all the secondary settings, but the light was unable to switch to L1. Suddenly, after several minutes of fiddling the light switched into L1 and all was well.

I'm still puzzled by this behavior. I don't abuse the light, expose it to water, shock, etc. It's clipped on my belt all day, and sits on my nightstand when I return from work. It seems the light just gets flaky sometimes.

I really want to figure this out, since I am interested in the newer Zebralights, but I feel funny spending so much money on a light if it's just going to be flaky like this. I figure this problem isn't widespread or we'd hear more about it on these forums. Anyone with any ideas as to why this is happening?

:thinking: Huh, that does sound strange.
I too normally just use eneloop in my SC51, but I did get a good deal awhile back on some Tenergy Ni-MH batteries which I use from time to time. Since they aren't LSD they do drain quicker. When they have drained down a bit sometimes I can no longer see a difference from High 1 and High 2.
But when I put freshly charged cells in everything is normal.
Not sure what to tell you.
Hope you get this resolved!

No other ideas? Come on, you guys know everything about flashlights...

silentlurker said:

No other ideas? Come on, you guys know everything about flashlights...

Click to expand...

Try looking at the tailcap. I have a couple SC51's and both of them had some kind of rubbery glue covering part of the contact area inside the cap. You may need a magnifying glass to see. I had to get it loosened with a small screwdriver and finished removing it with a rag over the tip. It was rubbery and wanted to not come off.

I believe this was causing my intermittent problems with mine not wanting to switch between high modes sometimes. At least the difference between the two modes wasn't as much as it should have been. Tightening the tailcap tighter would cure it, temporarily. I didn't have any problems on the lower modes, but didn't switch those modes often anyway, so didn't notice.

May not be your problem, but worth a shot.

Are your cells old with lots of cycles under their belts? Do you use a conditioning charger with them? It sounds to me like what you're experiencing is the cell not getting proper voltage to the driver. Try cleaning all the circuits, and using a brand new freshly charged cell and see what happens. If the problem persists, you've probably got a bum unit.

Definitely try cleaning all the contact areas (tailcap including spring, the end of the battery tube and the +ve contact at the head end). These have been known to cause problems unless thoroughly clean. Less often the tailcap spring has been known to collapse (try restretching it if that's the case). If that plus a known good battery doesn't fix the problem then you need to return it to ZL for repair/replacement.

If it was just H1/H2 then the battery is the most likely suspect, but seeing as L1 is also involved then it may be a problem with the LE (driver).

Please let us know how you get on.

Thanks for the advice, fellas. Let's see here... The batteries are probably not the issue, as they are brand new eneloops, charged in a Maha C800S. The contacts *look* clean, but I'll rub 'em down and use the light for a bit to see if that fixes the issue. Will update after I have some more use in it. Thanks again!