Vent without Flames, shortcircuit due to bad heatsinking. xm-l unsoldered itself!

Fichtenelch

Enlightened
Joined
May 23, 2009
Messages
435
Location
Germany
Hi,
Pictures first:

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Sold a flashlight to a co-worker, he had it the 1.st day. Used it for an hour for troubleshooting in a boeing 767. then he said that it got warm, wouldn't go on and started to smell.....
from the pictures you can see that this is an ultrafire c8 host. but the manufacturer forgot to think about heatsinking, since the pill does not really make good contact to the body. this did result in the led heating up and up (at 3A pretty quick ;)), rising until around 175°C, then the solder starts to melt and the led moves on the star, causing a short circuit! and that short circuit causes the battery to heat up even more until a point where it starts to vent.
in this case there was no poof, pipe bomb or anything really dangerous. but it could have happend.

I opened a dx cse case ;)
 

CKOD

Enlightened
Joined
Aug 3, 2010
Messages
708
Interesting... I figured an LED would turn angry blue before desoldering itself. Has anyone overdriven XM-Ls and had them turn blue? Or maybe the phosphorus is more heat resistant than we're used to. Was there any mention of it turning blue from your co-worker?

Glad the vent worked properly and there were no shens with flames, or tailcaps removing themselves.
 

Rej

Newly Enlightened
Joined
Mar 10, 2011
Messages
58
Location
Stoney Creek, Ontario Canada
Wow Fichtenelch....that's a bad run of luck, glad your friend was not hurt by a potentially serious problem:poof:
That 'Brinyte' looks like a clone (or vise-versa) of my KD C8 that I've had for 3 weeks now...personally been very impressed with the quality and 'sheer' amount of light (short run times though) this baby puts out on (1) AW18650-2600mah protected battery!!

Looks eerily familiar does it not?;
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However looking at your pics and the melted top of that 'GTL' 3300mah - 18650 battery would make me question the culprit being the battery short circuiting ''1st', causing the damage to the LED and driver. Have you heard of 'any' legit 3300mah - 18650 batteries?

If you look closely at your pic, that battery design 'appears' to have the PCB protection circuit located at the '+' terminal, while ALL other 18650's I've seen (AW, REDILAST, even 'crappier Ultrafire's) all have them installed on the '-' terminal?

Also that does not appear to be straight venting as such, but appears to be an internal short of the battery itself.....whether caused by the driver, lack of heat sinking or the battery....would sure make for a great debate:naughty:

I've had this KD C8 EDC'ing now on my dog walks and in some cases running it on high ([email protected] to [email protected]) for 30min STRAIGHT on high with no problems. Mind you, it has been 4-8 deg C outside and I did add 'thermal paste' on my threaded 'pill' (into the housing, by the heat sink fins) and stuffed the Gap between the reflector and the head with Aluminum foil;

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Personally I'd stick with 'Quality' cells...considering the inherent dangers associated with LiION cells, protected or not...especially with these new high draw lights coming onto the market.
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Fichtenelch

Enlightened
Joined
May 23, 2009
Messages
435
Location
Germany
It is a clone of the ultrafire c8, but they forgot to screw the pill into the body, it only has a spring to make gnd connection. the pill is only screwed to the reflector. so i admit that the led overheated, caused the short circuit and started the sequence.
the capacity of that gtl cell is a lie, but they're not bad...i'm glad it did not vent. and i don't think that the led started to turn blue. however, i'll have a closer look later and check if it still works when i resolder it ;)
 
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