How delicate are protected Li-Ions?

[Paul Baldwin]

Hi,

I fumbled my keys last night and dropped my S1A from waist height onto a concrete step. The torch was off at the time, picked it up, tried it to make sure it worked and nothing, not even the slightest flash. After failing to get it to work and being pretty dissapointed with the thing I tried the spare li-ion I have and it is thankfully working as it should. The battery that's failed is a Keeppower 14500 840mAh that's about 2 months old. I popped it in the charger to see what it did, the charger shows it as taking charge initially but 5 mins later it shows as fully charged. It reads 4.21 volts according to my multi-meter but refuses to work in the torch :shakehead
Is this normal behaviour for li-ions? I've been edc'ing an Ultrafire A10 with nimh since 2009 and never had a failure no matter how rough I've been with it showing people just how resilient led's are. This is the first and only impact that that battery has been subjected to!

Cheers

Paul.

 

[tripplec]

Well it was in the flashlight so there shouldn't be a dent in it. If so then through it away. Any dent can be a bad thing if you''re using it. You can try the cell again in the light. Maybe it got knocked out of position and the short charge cycle it indicative of its barely discharged. Meter the cell first if there is the nominal voltage of 3.7VDC or higher if much lower such as 2.5 to 2.9VDC I'd suspect something is wrong.

 

[vicv]

The protection circuit may have been damaged. I'd try removing the wrapper and PCB and rewrapping

 

[StorminMatt]

I agree with the others. Most likely, the protection circuit was damaged. This is quite likely ESPECIALLY with a 14500, since protected 14500s are very long in comparison to unprotected 14500s and the battery tube in most AA/14500 lights. As a result, spring pressure tends to be REALLY high on protected cells, which can cause damage to occur when the light is droppwd. On the other hand, I myself have dropped batteries (not in a light) from about the same height. And they worked fine afterwards. Try pulling off the protection circuit and rewrapping. You just may have a perfectly good unprotected battery.

 

[stephenk]

Sounds like you were unlucky. I have similar cells that have survived a few major falls in my Thrunite TH20. Sounds like the protection circuit was damaged. As others have mentioned, either turn it into an unprotected cell (take care not to short anything), or simply buy a replacement protected cell.

 

[Paul Baldwin]

Ok, thanks for the advice. I took it apart, removed the protection circuit and re-measured the voltage. Still showing 4.21 volts. Still refuses to work. Very strange.

 

[CuriousOne]

How you measure the voltage? using DMM ?

 

[Paul Baldwin]

How you measure the voltage? using DMM ?

Its not new but it's a Megger M7027.

 

[defbear]

Did dropping it turn the battery into a flat top with the button no longer making contact?

 

[Paul Baldwin]

Did dropping it turn the battery into a flat top with the button no longer making contact?

It appears you may be on the right track here? There was a slight indentation on the button top before I took it apart. The positive contact in the head is clearly visible so couldn't see how it couldn't make contact. However, I searched flat top S1A and found this thread http://www.candlepowerforums.com/vb...1A-amp-S2A-(TIR-Optic-XM-L2-1xAA-2xAA)-Review
"The light has a deep-set positive (+) battery contact in the head. There is also a black plastic disc surrounding it, which acts as physical reverse-polarity protection feature to protect from incorrect battery installation. So flat-top cells will not work in the light."
While not flat topped there isn't much showing on the top of the cell now, especially after removing the protection circuit. I haven't got a working soldering iron at the mo so can't try and dab a blob on there either to test the theory. I've given my A10 to a friend too so cant test it in that either.

 

[staticx57]

It appears you may be on the right track here? There was a slight indentation on the button top before I took it apart. The positive contact in the head is clearly visible so couldn't see how it couldn't make contact. However, I searched flat top S1A and found this thread http://www.candlepowerforums.com/vb...1A-amp-S2A-(TIR-Optic-XM-L2-1xAA-2xAA)-Review
"The light has a deep-set positive (+) battery contact in the head. There is also a black plastic disc surrounding it, which acts as physical reverse-polarity protection feature to protect from incorrect battery installation. So flat-top cells will not work in the light."
While not flat topped there isn't much showing on the top of the cell now, especially after removing the protection circuit. I haven't got a working soldering iron at the mo so can't try and dab a blob on there either to test the theory. I've given my A10 to a friend too so cant test it in that either.

Perfect excuse to buy another flashlight that will fit an unprotected 14500

 

[Paul Baldwin]

Perfect excuse to buy another flashlight that will fit an unprotected 14500

While I agree with that statement as I have a fascination with led's that led me here in the first place I'm afraid it doesn't fit with my mentality. I prefer to buy right and buy once. The Ultrafire lasted me since 2009! I did my research for a budget light, took my chance and it worked out. This quality £40 light had better not be worse than that derided £11 iirc Ultrafire! I've waited years for a decent jump in tech for a keyring EDC that doesn't use AAA.
I bought protected cells as the torch is IP rated, will see a lot of use and is effectively a small pipe bomb in the wrong circumstance that will spend a substantial amount of time next to some bits that are quite precious to me.