Hi, I bought an Ultrafire c12 around half a year ago.

the torch has served me well, but lately whenever I turn on my torch, it will either went full brightness, then became very dim, or has dimmed light straight away. I tried recharge my battery, but the problem persists.

all lighting modes have the same dimming problem.

I've checked my panasonic ncr18650pf during full charge, output is nominal (~3.8 V)

but sometimes the bringhtness of the torch has magically returned to normal

does anyone know what's the problem and the solution?



(PS: I usually do night riding with my torch always on full brightness)

contacts are unanodised

what do you mean by shorting the -ve to the end of the tube?

how to break into the driver part?

I've tried connected the -ve to the tailcap and shorted the +ve to a metal surface, the torch is fixed, for now.

Is this problem usually happens for ultrafire torches?