New Ultrafire 501B acting funny ...

Just got my second 501b after an agonizingly long wait, and it's doing an odd thing.

On brand-new, freshly-charged CR-123A batteries (tested out at an acceptable 4.17v), the light flickers just slightly. It's almost like there is a slight pulsing to the light, not going all the way off between pulses but just, well, pulsing. It pulses at slightly more than 1 Hz.

I've checked the tightness of the components and blew out the tube and end cap with no effect.

Anyone have any ideas for me? Would that tend to be the clicky, or the pill/driver?

TIA.

.
.

Well, never mind about the clicky - I just switched it out with another one and it still flickers. It's almost like a little twitch.

Weird.

.
.

Doesn't sound like its the switch, I think you can cross that off the list.

I think when the LED goes into auto-strobe, it is a sign of over-driving. I have some 18650 direct drive showerheads that strobe like that. One of my projects was a 5V LED direct driven off a pair of CR123 primaries, and it strobes like that too.

*EDIT*
Heres something else you can try to completely rule out a host body conduction issue. Pull the P60 module from the light. Take one of the CR123 cells, 2 segments of wire and contact B+ to the small spring and B- to the larger spring. You are basically powering the module at the lowest voltage level its spec'd for, and eliminating the host body from the equation. Does the strobe stop? If you get solid non-strobe light from one cell, that makes me think the DC-DC circuit is over driving the LED, or you have a conduction problem through the host.

Try this...

Many thanks for the comprehensive reply, Kramer. I'll try the experiment as soon as I get the chance.

In the meantime, will overdriving do anything besides shorten the life of the emitter? I don't want to have a battery go explosive on me or anything. I'm running a pair of Trustfire 880mAh 3.6v Li-ion rechargeable 16340's like in my other WF-501B.

.
.

I would try what kramer said. If you still have a problem it is most likely the circuit board.

I was finally able to try the test Kramer suggested, and the light does indeed still "wink" or strobe very slightly, so I guess it is the board.

I guess my question at this point is whether this is a problem I should take up with DX. If it's not going to cause my light to blow up on me or create any other safety issues, I'll live with it (and maybe order another drop-in to replace it eventually).

So ... is it safe to operate like this, or can I expect overheating and venting, or other issues?

.
.

I doubt the cell will vent. But if it is indeed an overloaded LED, you will kill the LED. It will turn brown in the center and drop output or just flat out not illuminate at all.

Curious does yours have the 3-18 Volt module? Theres some CPF history of the DX:11836 3-18V module overdriving the LED.

Could be driver , or just a bad solder joint .

Flicker is usually a bad joint , or possibly a mild short . :thinking: In my experience in anyway . Check current draw ..

this sounds oddly like PWM.. but huh...

kramer5150 said:

I doubt the cell will vent. But if it is indeed an overloaded LED, you will kill the LED. It will turn brown in the center and drop output or just flat out not illuminate at all.

Curious does yours have the 3-18 Volt module? Theres some CPF history of the DX:11836 3-18V module overdriving the LED.

Click to expand...

I guess I'm too dumb to know how to answer your question. This flashlight is set up for 1x18650 or 2xCR123A, so it's rated at 3-8.4v on the DX website.

I have another one just like it and it doesn't "twitch" like this one. I liked it so much I got this second one.

If it helps any, I've noticed that the "twitch" (I can't really call it a strobe or flicker, since it's barely perceptible unless you really look) doesn't start immediately ... turn it on high and it burns fine for several seconds, then it twitches ... then after it's on for a minute or two the twitching comes a little closer together. It's like it starts after it warms up a little.

I'm concluding it's a problem with the regulator. I think I'll order another P60 drop-in and just use this one until it comes in. Heck, it's only about 11 bucks, and it has to be worth more than that not to have to return something to DX!

.
.