UltraFire C12 XML-U3 Problem

Hi Everyone, new to the forum!

Long story short after some research I plumbed for the above light. Charged the battery today and went out on my bike to test it out, everything was fine. Light worked as it should.

Went outside later on and used the light however the high beam doesn’t stay on, nor does strobe or SOS. For some bizarre reason only MED and LOW beam stay on for any period of time over 1 second.

Any thoughts? I’ve been waiting almost a month for it to arrive for it to break within the day.


Try to use another fully charged battery. The High, strobe, and SOS modes use max brightness (I think).

Make the battery is charged an empty battery will be 3.6v or less and a full battery will be 4.2v. Maybe the PCB is tripping on the battery. Or there could be a short, the reflector could be touching the wire or les.

Batteries are both at 100%, I bought a Trustfire Multi charger with the light that goes green for each battery once they are fully charged.

Reflector doesn’t appear to be touching the LED or anything from what I can see.

Do you have a link for the batteries and charger? Welcome to the forum.


Thats the charger & batteries being used with the light

This will more than likely be your problem. The batteries are totally sub par, I say this nicely. Panasonic, or some of the better brands may fix your problem. Something like the ones below will be a lot safer to use. Just check that the batteries are not to long for your light though.



those batteries are known to be junk.
had 2 last week in a bike light that were over 300m ohm esr.
not surpisingly it worked fine with some laptop pulls.
the originals were no good from new!

hmmm ok cheers, any recommendation which of the Sanyo’s to go for as there is about 10 to choose from….
also a website that doesn’t take 45-60 for them to arrive in the UK

These are great batteries

However your problem could be the switch, the circuitry or the LED, or some kind of flashlight specific problem (loose wire, shorted out by the reflector, poor contacts.

Batteries are surface mail only. I think DHL or UPS ships it by Air but I could be wrong and it's expensive