Is battery ruined?

wildweed

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Hello all,

I just got a few Keep Power 18650s 3400mah batteries in the mail. I was charging them today and after they charged I wasn't paying attention when taking out of charger and dropped one from counter to floor. The bottom wrapper cracked and pilled back. I check voltage and it was reading 4.19v but it won't power a light.( Tried 2 different lights ) I got a little nervous and put battery outside for now. Is the battery ruined? I will try and post pics.
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[/URL]IMG_5651 by wildweed78, on Flickr[/IMG]
38185359664_735217bc7f_z.jpg
[/URL]IMG_5650 by wildweed78, on Flickr[/IMG]
 

wildweed

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Thanks for the info. I did not think it would be. I may check on re wrapping it. Heck I may just recycle it. I have plenty. It just sucks. I just got it the mail yesterday :-((. I have never had one do that.
 

Gauss163

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There are prior reports of drops damaging the protection circuit.

Warning: due to the wrapper damage it is now much easier to accidentally short-circuit the cell in a way not protected by the PCB. The exposed metal strip running down the length of the cell is positive, and the (now exposed) can is entirely negative. The two are separated only by the yellow kapton tap. A small metallic object (e.g. coin, key, paper clip) could easily connect the two and short the cell (in a way that bypasses the protection chip). To avoid such shorts you should wrap some tape over the exposed part of the cell.
 

wildweed

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Thanks!

I don't think I am going to mess with it. I thought about wrapping it or covering it with electrical tape or something but I think I am going to eat the cost and move on from this cell. It's my fault for dropping it. It has never been used but better safe then sorry

There are prior reports of drops damaging the protection circuit.

Warning: due to the wrapper damage it is now much easier to accidentally short-circuit the cell in a way not protected by the PCB. The exposed metal strip running down the length of the cell is positive, and the (now exposed) can is entirely negative. The two are separated only by the yellow kapton tap. A small metallic object (e.g. coin, key, paper clip) could easily connect the two and short the cell (in a way that bypasses the protection chip). To avoid such shorts you should wrap some tape over the exposed part of the cell.
 

hiuintahs

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I'd rewrap it with those heat shrink wraps that you can buy in Ebay. Do a run time test and see if it trips when the voltage is depleted. Verify the voltage when it did. If if works as it suppose to I'd keep it. If not mail to me and I'll pay the shipping :D.
 

wildweed

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I have thought about rewrapping it. Hmmmm I may try it but if I don't I'll PM you and have no problem sending it to you.

I'd rewrap it with those heat shrink wraps that you can buy in Ebay. Do a run time test and see if it trips when the voltage is depleted. Verify the voltage when it did. If if works as it suppose to I'd keep it. If not mail to me and I'll pay the shipping :D.
 

zespectre

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I'm always a bit hyper-cautious about damaged battery packs.
The cost of a new cell is way less than the cost of damage from a runaway pack
Fire and explosions.... nope nope nope.
 

hiuintahs

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Like vicv mentioned you could also take the protection circuit off and then rewrap the cell. Take a look at this thread:
http://www.candlepowerforums.com/vb...0mAh-18650-batteries-too-wide-now-retrofitted
You'd end up with a non-protected battery........but most of mine are that way anyhow.

However, I'm pretty sure that all that happened is the wrapper split. I've had it happen to me too. If you can measure voltage of the battery and doing a visual inspection yields no obvious physical damage to the pcb, or dents in the battery, then I'd opt for re-wrapping it.

Just to feel real good about it, a run time test to take the voltage all the way down until it trips the protection circuit would validate the protection circuit. I have a capacity load tester and so it wouldn't have to be done inside a flashlight. I would not run this battery like it is in a flashlight because that metal strip is the (+) side of the voltage and a flashlight tube is the (-) side.......so it does need to be covered up if this battery is to ever be used. If physically it looks good.........just a split wrapper, then wrap it and then do a trip test.

As an FYI, if you do a trip test and it does trip (and stays tripped after you're done), then to reset the tripped battery (because it now will show 0 volts and many chargers will not know what to do), you just put it in parallel with a charged battery for a couple of seconds which allows current to flow through the body diode of the mosfet switch on the protection circuit and it only takes a second or two and the voltage will now register well above the trip point with the now reset protection circuit..........and your charger will now register that there is a battery when you put it in the charger.
 
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Gauss163

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[...] However, I'm pretty sure that all that happened is the wrapper split [...]

Why are you "pretty sure"? Given that the OP said it won't power a light, there is more evidence for damage to the protection circuit.

In any case, before any further use or testing be sure to tape over the exposed metal portion of the can (be sure to cover the entire exposed can since it is all negative, unlike other common batteries).

Try giving it a very brief low current charge (that might reset the protection circuit if it is in some strange state).

Even if you can revive it, you should treat it with extra caution since the protection circuit may have been damaged so it may no longer offer full protection
 

hiuintahs

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Why are you "pretty sure"? Given that the OP said it won't power a light, there is more evidence for damage to the protection circuit.............
Because of his statement:
"I check voltage and it was reading 4.19v"
However if it won't power a light, then he must have put it into a flashlight tube the way it was and who knows exactly what has happened. It would not be hard for me to figure it out which is why I offered to pay for shipping if he was just going to throw it away. Worst case I repair the protection circuit but I probably wouldn't bother. The one nice aspect of taking off the protection circuit is that you don't end up with a flat top battery but with a button top non-protected battery. Flat top non protected batteries are easy and cheap but button top unprotected are not so plentiful :).
 

wildweed

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I did put it in a 6P and it would not light up. I also put it in my Hound Dog 18650 and it powered it but when I turned the head it went off. It was after this I checked voltage and it was at 4.19. My guess is the exposed strip was making contact with tube. Not sure but thats when I got nervous and posted on here. I think I am going to tape it up and check voltage again. It does not look dented or deformed in anyway. I tend to agree with zespectre.
A new cell isn't that much.....

Thanks for all the info everyone!






 

vadimax

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Definitely its protection is compromised, but if you remove it and rewrap the battery itself, it is absolutely OK.

Personally myself I have purchased a good DMM (digital multimeter) and from that point use unprotected sells only. Those protection boards are just one more element to fail (IMHO) :) More of that, decent light feature internal over discharge protection and there is no sense to duplicate it. Quality lights and quality chargers make us, flashaholics, happy :D
 
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