Ultrafire C8: annoying mode behaviour

Hi Folks,

I bought an Ultrafire C8 (Q5) for very little money (USD 8.59 shipped). The finish has some dings, but nothing that bugs me, it's ok for the price.

But what really annoys me is the mode switching. The mode configuration is high - mid - low - strobe - sos. When switching on the light, it always changes to the next mode, no matter how long you left it off. So for example, you use it in low mode, switch it off and put it aside. The next time you switch it on it will start in strobe...

So what do you think, is the driver faulty or is it just crappy designed?

Thanks in advance,


Commonly referred to as "Next mode memory" across other forums. its generally intended to be that way... and I agree its my least favorable mode flip UI.

So it is broken by default... Maybe I'll do my first mod on this one and see if I can swap the driver. Not much lost if I mess it up

I have a 3 mode light (H-L-Strobe) that has that behavior. I hate it (that type of memory behavior, not the light).


Probably crappy design, but maybe somebody will know of a soldering hack that could change it for you.

I've read of other lights that do that. Their solution was before turning it off to put it into the mode before the 1 you want it to be when you turn it back on.

The alternative is probably a driver change.

My son's XML Ultrafire C8 has a memory, my Trusfire always come on in high mode.

What you said... i to have a torch that has incremental memory. Luckly mine so fudged it forgets after about 15 seconds of off and comes back to high. Ill too be replacing the driver soon.

Here's a good driver for your light if you want multiple modes...


1A drive current and user selectable mode groups including 2-mode high/low.

If you want a single-mode thrower, I have succesfully used these in a couple of my lights...


These seem to be driving the emitter much harder than advertised values, as both my lights using this driver show a tailcap current of 2.2 amps. Maybe DX sent me the wrong ones... I'm using one in an XP-G R5 pocket-rocket and the second in a XR-E R2 aspheric P60 thrower with good (ie. bright!) results...

Yes, it must be an issue with the cheaper Q5 version. My UF C8 XM-L has memory and works great.

Thank you, that is useful to know. Are 2.2 amps safe for the older XR-E emitters? The tailcap reading on my C8 on high is 1.8 amps and it gets warm on the outside pretty soon.

BTW, I even found a Q5 1-mode replacement pill, but the current draw is not stated.

I am also tempted to try an XM-L in there, but don't want to lose the throw. The beam is really nice and tight now.

Over 1.5A is not safe.

I wouldn't say "not safe", as in loss of life and limb, but I assume it's very bad for the emitter's general state of health... Laughing

I don't know the efficiency of this driver, but the LED won't be seeing quite the full 2.2A. But it's still getting a LOT. I'm sure I'm shortening the life of the emitter a lot by putting this much power through it. Of course, it's a novelty P60 thrower that is only used for brief periods, never more than a few seconds at a time... And if the emitter burns out, I already have a spare on hand in my kit...

I already ordered the single-mode driver. I think, even if it fries the emitter sooner or later, chances are good that I get another flashlight before that happens

Be sure to post your ressults here when you get the new driver in from DX (whenever that happens). I'm curious to see if you get the same high current levels as I'm seeing with mine...

Today was a successful day because I did my first flashlight mod . Found the driver in the mail when I got home (three weeks shipping time isn't bad for DX) and went to work immediately.

Everything turned out good even though I encountered some surprises. When I took out the old driver I saw that there was no brass insert in the pill, so I had to solder the ground connection directly to aluminum (Not. Funny.). And then I noticed that the LED board was sitting loosely on top of the pill with NOTHING in between. Since I had no thermal adhesive I figured that arctic MX-2 thermal compound was better than nothing, considering that the reflector does apply some pressure on the LED.

The flashlight works fine now as a 1-mode-thrower. BTW, can a driver improve the beam pattern? I've got the impression it is less ringy now.

The tailcap current is about 1.7 to 1.8 amps now, roughly the same as before.

Here are some pictures:

The new driver

My soldering job

Well, this doesn't look exactly like being made for eternity

FWIW, this is the old, crappy driver

WHOA!!!! How did you pull this off? I have never (ever) been able to successfully solder anything onto Aluminum. The solder just *refuses* to bond to the Al. I have scrapped at least 3-4 DIY repairs over the years because the solder instantly forms a cold joint with no adhesion. On one project I was able to get around it by applying blobs of solder around the perimeter of the board, file them down a bit and press it into the Al pill.

Can I ask what solder brand you used and what flux you prep'd the surface.

thanks... Oh and GREAT job on the repair too!! Every once in a while DX does come through.

Just one word of caution... the LED+/- blobs look a little tall there, and they can short across the back of the reflector. I have found (generally) bad/strange things can happen when the reflector creates a short here. I use 3M packaging tape stacked up 3-4x, a hole punch and cut an insulator disk and stick that onto the back of the reflector. Just to play it safe.

Well I guess I'm a natural thanks kramer.

I read somehwere (don't remember if it was here) that you should first put flux on the aluminum and then use sandpaper to grind a little bit of it away, while the flux keeps the aluminum from oxidizing at once.

I also laid the tip my soldering iron flat on the rim of the pill instead of just using the tip, and then I kind of dragged the solder from the driver board over to the edge. Had my iron on the 360 °C setting. But I don't know how stable the connection is.

Edit: Maybe it helped that I still use the older, lead-containing solder. I just got so much of it left.

Edit 2: Oh, and this is the flux I use:
It is of grease-like consistency, light yellow in colour and smells kind of sweet.

Oh, I didn't even think of that possibility. But luckily there is a plastic washer on top of the LED board to prevent that. But that's something I have to keep in mind for future projects.


So you spread down a layer of solder paste first, and then sand/scuff the Aluminum through the paste?

What he said!

Good to know!! thanks, some day I am sure this info will come in handy. I'll have to search around for old lead solder... although breathing that stuff can't be healthy... LOL