My Driver Has Gone Berzerk ! ( Fixed ! The battery was bad . )

My treasured Convoy S2 with a 5C XML , eight chips on the standard two mode-group driver , has gone crazy !

Yesterday , it started acting up . The only mode it currently has is a weird multi-level strobe !

High-Medium-Low-High-Medium-Low-High-Medium-Low-High-Medium-Low-High-Medium-Low....!

It is a very disorienting mode , and not at all useful to me .

I have not dropped the light , or mishandled it in any way .

Has anything like this happened to anyone else ?

I’ll make some guesses:

  • C1 may be damaged, check the solder joints on it. It’s exposed on the bottom of the PCB.
  • Contact problems - eliminate the tailcap by jumping BAT- to the body with a bit of wire or braid.
  • Contact problems - do you still have good contact between the driver and the pill?

IIRC I may have run into something like that before with C1 being the culprit.

It is the first time I hear of a 105C failing, weird story...

Perhaps it is not a driver problem, but a loose contact somewhere else in the light causing rapid mode changes, perhaps inside the switch?

I’ve had something like that happen with E-switch drivers, when the wiring is messed up and it thinks the E-switch is being held down when it’s not.

Haven’t heard of something like this happening with an unmodded 105c. They’re pretty rock-solid reliable.

First of all , thank you very much for all of the suggestions !

So , as it happens , I did the old paperclip trick , and sure enough , the light functioned properly .

After examining the switch , I determined that it wasn't making proper contact . So I put a solder blob on the edge of the contact ring and that fixed the problem !

Since the iron was still hot , I replaced the stock driver with a 3.4 amp Qlite .

No more blinkies on my EDC !

Thanks again for the help .

Hot dog! That was a fast turn around.

When the problem reoccurred , I checked every connection and everything else I could think of .

Then I tried another battery in the light .

Well I be damned . The nearly new NCR18650A I had been using was causing the problem !

It was down to 2.34 volts . I never run my batteries down past 3 volts so something had gone wrong with that particular battery . It hadn't even been recharged more than two dozen times .