17670 issue with Downboy 1000 + SSC P4

I have a Downboy 1000 running a Seoul P4 in my gutted out L1 (sorry, this is probably the third thread about issues with my first mod ...)

It runs great on two primaries - I love it. I just got two protected 17670 cells from AW today, figuring they would work great in this light. However, when I turn the light on high, it flickers quite a bit. I tried leaving it on for a while, and tried both cells (fully charged) ... no matter what I do, the highbeam flickers. When I switch back to primaries, the beam is normal.

Any ideas? My understanding is that the Downboy runs in regulation above 3V, and currently both cells are around 4.2. I can't for the life of me figure out why this is happening.

Thanks for the help ... again

AW should have shipped the cells with magnets make sure they sit in the middle and only touch the (+) of the downboy. If you didnt get the magnets you need to put a solder ball on the (+). It sounds like bad contact

I do have a solder ball on the (+) contact. When I first noticed the flickering, I added a bit more to the ball in case that was the problem with the same results. That doesn't rule out that it is a bad connection, but it seems like the primary cells would have the same issue, wouldn't it?

Actually, it looks like you were right. After thinking about what you said, I realized that the ball of solder has a very small contact point with the battery. I resoldered the ball and used an old battery to flatten the it down to more of a plateau. I also scuffed it up a bit with sandpaper. It works now - thanks!

You probably had what they call a "Cold Solder Joint" its basically a ball sitting on another ball without mingling. Watch out when making solder balls if you get too much flux inside and reheat it the flux can explosively vent, goggles will keep it out of your eyes. It hurts and burns, not fun.

The primaries should have bigger buttons designed to get into the recessed (+) in the head. Or I should say the head is designed around CR123a format. Some of AW's secondaries are without Button tops hence the magnets. But they can slip and ground to the body in some lights. Not a prob in the SF KL1 since its anodized.

use of magnets with li-ion cells creates dead short dangers and is not recommended. don't count on anodization to protect from dead shorts. magnets can easily bridge from positive nipple to battery case.

use of magnets during charging is still not recommended as magnets can cause extra resistance, changing termination point.

nein166 said:

You probably had what they call a "Cold Solder Joint" its basically a ball sitting on another ball without mingling. Watch out when making solder balls if you get too much flux inside and reheat it the flux can explosively vent, goggles will keep it out of your eyes. It hurts and burns, not fun.

The primaries should have bigger buttons designed to get into the recessed (+) in the head. Or I should say the head is designed around CR123a format. Some of AW's secondaries are without Button tops hence the magnets. But they can slip and ground to the body in some lights. Not a prob in the SF KL1 since its anodized.

Click to expand...

nein166 said:

You probably had what they call a "Cold Solder Joint" its basically a ball sitting on another ball without mingling.

Click to expand...

Interesting. Also, isn't it possible to "burn out" solder? The reason why I say this is because I have heated and reshaped that ball of solder probably 10 times during this mod. At first it was too tall for the primaries, then too short, etc.

Either way, if it happens again, I'll desolder it and put all fresh solder on. Thanks for the explanation ... maybe after enough time I'll have knowledge to contribute something other than questions .

Im not sure if the downboy is intended to stepdown from a single li-ion, the voltage difference with the Vf of the led is very low.


Pablo