18650 battery?

[zxcvbob]

I have some old laptop battery packs.  (very high quality unprotected 18650 cells, at least one dead cell per pack.)  If I take them apart, the good cells should be OK for flashlight use if I charge them singly and use them singly, right?

I'll buy protected 17500 cells for my 3xCR123A flashlight.  Actually, they fit loose enough I /could/ use 18500's.

[mtnbkr]

I tend to shy away from Ultrafire stuff. Worth reading:

http://www.candlepowerforums.com/vb/showthread.php?280909-Ultrafire-18650-3000mA-exploded

Cheap chargers tend to be more likely to overcharge, especially when charging in pairs. Overcharging is likely what caused the above linked explosion.

Scary.  I have 4 Spiderfire 18650 (also 2xCR123) lights.  It seems the biggest threats from 18650 batteries comes from the charger or multi-18650 lights where one cell is "off".  That said, I may either spring for "good" batteries and chargers or just start using 2xCR123 batteries in each light.

I've had the lights for a couple years.

Chris

[bedlamite]

Scary.  I have 4 Spiderfire 18650 (also 2xCR123) lights.  It seems the biggest threats from 18650 batteries comes from the charger or multi-18650 lights where one cell is "off".  That said, I may either spring for "good" batteries and chargers or just start using 2xCR123 batteries in each light.

I've had the lights for a couple years.

Chris

Problem is that even the "good" batteries are still made in China. Like I said in my earlier post. When it comes time to replace these I'm converting to LiFePO4 for lights, probably within the year. Lower capacity, but significantly less fire hazard.

[mtnbkr]

In that case, I may just go to dual CR123 batteries per light.  It supports either.  2xCR123 cells gets expensive, but I don't use these all that much. 

Chris

[Marnoot]

seems the biggest threats from 18650 batteries comes from the charger or multi-18650 lights where one cell is "off"

I think that's the case. Laptop battery packs are basically packs of 18650s and it's been several years since there was a spate of laptop fires. I think the three main differences between these safer laptop batteries and the 'splody 18650s are that the laptop has a built-in high-quality charger, that the 18650 cells themselves are from a reliable manufacturer, and that the cells have good protection circuits. The kind that explode tend to have issues with one or all three of those things.

I've decided that my risk is fairly minimal if I use good quality protected cells, known-reliable safe charger, and I've started double checking by checking voltage on the batteries before and after I charge them with a multimeter. If they're over-discharged before, or over-charged after, they'll get disposed of. Ditto if one cell is more discharged than the other after use in my 2-cell light. So far they've always been fine. I think using unprotected cells in one-cell lights is pretty safe, so long as you're double sure to use a quality charger, and it's more important to check them with a meter before and after charging.

I do wish that manufacturers of flashlights that officially take 18650s would put some sort of pressure-vent plug in the body that would keep water out, but pop out if pressure built up in the battery compartment.

[zxcvbob]

I found a discarded Canon lithium ion camera battery in the battery disposal box at work today.  The label says 7.4V 1100mAh and CƐ and "Made in Japan"

I measured the voltage and it was 7.45V, so I tore it apart (not easy.)  Inside there were two 18500 cells and a protection circuit.  I know they are mostly discharged, but I tried them in a couple of LED flashlights.  They work OK in the cheap 3xAAA lights but fit pretty loose.  A 18650 would be better, or I can put a neodymium magnet on the end to shim it, and maybe make a cardboard tube to keep it from rattling.  I have some dead other Li-Ion batteries that I think have 18650's inside.

The pair of them fit really nicely in my 3xCR123 flashlight if I took out the big coil spring that goes around the CR123's, but it wouldn't light up.  The spring completes the circuit from the tailcap, even though the body is aluminum.  :(  I put the CR123's in without the spring and it wouldn't light that way either.  So I guess I'll have to get some 17500's if I want them to work.  Either that, or make a new flat conductor to run from front to back in the tube.

Is that WF-139 charger linked earlier any good?  (I see they use that model number for several different cheap chargers)