Flickering Arc4

My Arc4 started flickering at max brightness. Not a battery nor a contact problem, it is the light itself. Is someone aware of a known fix?
Thanks

Anthony

When did this happen? When you first bought it or recently?

-vince.

I bought it last May. Only yesterday it started to flicker on level 1. I know many Arc4 seconds have this problem, but this is a first...

Anthony

ROL, it's impossible to tell exactly what's causing your flickering problems without actually seeing the ARC4.

some ARC4 had contact problems related to hyper-sensitive to batt length issue.

try inserting a wadded up aluminum foil disc aprox. 1.5mm thick on neg batt side to see if this improves contact.

if this improves performance, then add a blob of solder to make permanant. See the tailcap modd thread for details.

It keeps flickering, even powering it with a stabilized PS. Any suggestion? Thanks
Anthony

For those who may be interested, I believe to have found out why. My Arc4 (# 1206) draws 0.6 Amps at lev.3, 1 Amp at lev.2, and 1.65 Amp at level 1.
At 1.65 Amps, there is too much voltage sag from the battery, or from the 1.5 Amp max. PS I used. Subsequently, the light flickers slightly.
Is that normal?

Anthony

What is the cell's voltage at 1.65A?
The easiest remedy would be to avoid level 1.....

Ray_of_Light,

The level 1 current draw of 1.65A (presumably at 3V) is way higher than the power supply was designed for and should be considered a defective light. The power supply worked quite well at 2.5W and was rapidly dropping in efficiency by the time it reaches 3.5W and hit the point of no useful additional output soon thereafter.

This indicates you have a poorer quality LED in the flashlight.

The most likely cause of the flickering is an instability in the voltage sensing and compensation circuit. There are a couple of different causes for this but one is a hardware problem that changes the time constant of the control loop and makes it unstable. In any case, the problem cannot be fixed.

Although the term flicker does not describe the situation very well, the light should not "flicker" on level 1. That said, there is a situation which is normal and which can appear to be a low amplitude (visible but not a large change in brightness) and low frequency flicker. If the battery voltage is changing (dropping) rapidly, the output power can change from moment-to-moment and due to rounding errors, the light will get slightly brighter and than a few moments later get slightly dimmer - emphasis on slightly. If that is what you are seeing, that is normal. Otherwise not.

Henry.

ROL, have you check your serial number to see if your light is listed as a second.

drawing too much current was listed as a reason for grading to second.

I believe anything drawing more than 1.26A on level 1 will be classified as seconds.

Henry,

thank you very much for your explanation, that matches my observation completely. I tested the light with a 3.7 V Li-Ion and works perfectly, drawing only 0.8 Amps in boost mode.

Cy,

The light was sold as a first and it is a first, but I never realized of the level 1 was "flickering". It is not a big problem, also because the light has a lovely LED tint, but it is highly annoying for me...

Anthony

I own a Rev. 2 second #1337 which experienced the level 1 flickering. I've been running the JSB-123 hi-power 4.2 volt li-on in it and no more flickering on level one. So it appears that a higher voltage battery may have some impact on eliminating that unwanted flickering. These batteries from Jon Sidney seem to be working very well. /ubbthreads/images/graemlins/thumbsup.gif