POTENTIAL DANGER?

[Capolini]

This is a Protected CYTAC 18650 3400mAh BT battery that I discovered is a NCR18650B RE WRAP. 2.8 years old.

I noticed that when I put this battery in the charger that it continues to slip off of the positive contact terminal. It seemed that the BT was out of alignment so I decided to re wrap it and center the little White retaining ring better. I could actually move the BT back and forth with my thumb nail. That can not be good,it should be stabilized and have no movement! This is when I decided to sacrifice the battery!When I unwrapped it there was the typical Panasonic NCR18650B underneath.

I proceeded to take off the NCR wrap to completely expose the battery. I took off the protection circuit on the bottom,so now the wire that leads to the positive contact was the only thing holding it.

I AM AN AMATEUR and a NOVICE WHEN IT COMES TO ELECTRONICS!:naughty:

At this point I decided to REMOVE/BREAK OFF the wire so that the protection circuit was not dangling and so I could get a better view as to why the BT was not stationary as it should be. So I got out my mini craftsmen screw driver! As soon as I tried to severe the wire connected at the BT end there was a small spark and a puff of smoke! No doubt I short circuited the battery,that was my first thought! Second thought was,,,,,,,,is this battery going to vent or possibly explode now?! I got a bit concerned and put the battery outside on my balcony. I was ready to go to bed and thought,"what if" this battery vents or explodes?! So I wrapped it up[afraid to recycle at this point!] and threw it in the DOGGY trash can that that is provided for the residents.So if there is a it will be far enough away from my Second story condo!!!

A FEW QUESTIONS:

1.With the BT being unstable what would have been the worst thing to happen if I continued to use and charge this battery? a SHORT or worse?

2.Was there any DANGER in me trying to break off the protection wire which resulted in a puff of smoke and a small spark?!

3.How is the BT fastened? I did not get a chance to find out because I STOPPED MY EXPERIMENT when the spark and puff of smoke happened! I think I heard someone on here say w/ some glue and that white retaining ring!


TIME IS YOURS LADIES AND GENTLEMEN,,,,,,WHAT ARE YOUR THOUGHTS?

 

[Gauss163]

This post explains the likely reason for the short (where the "short piece of metal" was your screwdriver blade). Keep in mind that for Li-ion cylindrical cells - unlike common consumer batteries - the entire metal can is the negative terminal. In (most) protected cells, the metal strip extends the positive button terminal along the entire side of the can, where the terminals are separated by only a thin strip of (Kapton) tape.

 

[Capolini]

This post explains the likely reason for the short (where the "short piece of metal" was your screwdriver blade). Keep in mind that for Li-ion cylindrical cells - unlike common consumer batteries - the entire metal can is the negative terminal. In protected cells, the metal strip extends the positive button terminal along the entire side of the can, where the terminals are separated by only a thin strip of (Kapton) tape.

Thanks,....could you elaborate or give a succinct answer to my questions?


1.With the BT being unstable what would have been the worst thing to happen if I continued to use and charge this battery? a SHORT or worse?

2.Was there any DANGER in me trying to break off the protection wire which resulted in a puff of smoke and a small spark?!

3.How is the BT fastened? I did not get a chance to find out because I STOPPED MY EXPERIMENT when the spark and puff of smoke happened! I think I heard someone on here say w/ some glue and that white retaining ring!

 

[Connor]

Rule #1 of the rewrap club: Do not short circuit your cells. ;-)

I didn't quite understand what was wrong with your cell, but shorting is about the worst that can happen:
-you can burn yourself badly
-the cell will overheat very quickly and possibly explode/vent with flame
-do not use cells that have been shorted for more than a moment because they will be damaged internally and possibly become unstable

I would also advise you not to use any LiIon/LiPoly cells when you are in doubt that the cell is mechanically intact (you mentioned that the positive terminal was loose).
Do not try to "fix" a broken LiIon/LiPoly cell, it's not worth endangering yourself (or others) - better buy a new cell from a respectable manufacturer (Sanyo, LG, Samsung ..) and treat them with care.

 

[Capolini]

Rule #1 of the rewrap club: Do not short circuit your cells. ;-)

I didn't quite understand what was wrong with your cell, but shorting is about the worst that can happen:
-you can burn yourself badly
-the cell will overheat very quickly and possibly explode/vent with flame
-do not use cells that have been shorted for more than a moment because they will be damaged internally and possibly become unstable

I would also advise you not to use any LiIon/LiPoly cells when you are in doubt that the cell is mechanically intact (you mentioned that the positive terminal was loose).
Do not try to "fix" a broken LiIon/LiPoly cell, it's not worth endangering yourself (or others) - better buy a new cell from a respectable manufacturer (Sanyo, LG, Samsung ..) and treat them with care.

THANKS,,,,,,,

Some misunderstanding here.I was not trying to fix, re wrap[again] or save the cell......I sacrificed it once I saw that the positive terminal was loose. I was not thinking or realizing that it would short out w/ my mini screwdriver!

I have re wrapped dozens of cells,,,,I was doing and operation/experiment with this cell!!

The cells that you mentioned[Sanyo, LG, Samsung] and the Panasonic NCR18650B applicable to this experiment, ALL are quality cells along w/ my Sony VTC5's


GUTEN TAG!!

My Girlfriend's "MUTTI" was born in Kindenheim, Germany,,,,,,~150 KM SW OF FRANKFURT and 20KM WEST of WORMS:twothumbs

 

[NoNotAgain]

The button top is supposed to be spot welded to the top of the battery. You should have seen two or four small indentations on the button. If the button or the top of the battery wasn't clean, then the spot weld won't fuse.

99.9% chance the cell is fine. After a rewrap, you would have had a decent non protected "B" cell.

 

[Capolini]

^^^^^
It was an OLD cell so I sacrificed it! Wouldn't you have to remove the protection circuit and the wire and the BT to make it a non protected cell?,,,,,or just leave it as is?

 

[NoNotAgain]

^^^^^
It was an OLD cell so I sacrificed it! Wouldn't you have to remove the protection circuit and the wire and the BT to make it a non protected cell?,,,,,or just leave it as is?

The easiest way would have been to remove the lose button top and pull it away from the cell side. Then pop the protection circuit from the bottom. You might have had to Dremel the remains of the spot welded connection to clean the negative terminal.

I purchased a battery tab spot welder a few months back to rebuilt some 8 cell packs. I've used non-protected batteries, partially due to cheaper price on the cell, and I'm not looking for an issue with the protection circuitry.

The best circuits IMO are made by Seiko. A few of my batteries that were protected cells had the 2.8 volt cut off voltage.

Here's a pdf from Seiko on the protection circuits offered. http://datasheet.sii-ic.com/en/battery_protection/S8211C_E.pdf

Digikey has the circuit I'm using for $2.72 each.