Are 18650s suppose to do this?

Every time I take it out after use to charge, I see that the battery develops a dent that got deeper and deeper over time. I never drain my batteries.

Here's a picture.



Thanks!
-Chris

Are you using a McClicky switch?

I would say that the dent is not normal. It may not even be safe. What kind of flashlight are you using? I have lots of lights and have never seen such a deep dent. I see scratches and marks from springs, no dent. Some batteries are longer than others. Maybe you could use a shorter battery. You could also put a small magnet on the battery to protect the negative end. You could also cut the spring shorter.

Damaging the protection circuit at the bottom of the battery could get you into trouble...

MattSPL said:

Are you using a McClicky switch?

Click to expand...

No. I'm using a clicky tailcap switch.

HotWire said:

I would say that the dent is not normal. It may not even be safe. What kind of flashlight are you using? I have lots of lights and have never seen such a deep dent. I see scratches and marks from springs, no dent. Some batteries are longer than others. Maybe you could use a shorter batter. You could also put a small magnet on the battery to protect the negative end. You could also cut the spring shorter.

Click to expand...

It's a "Tac Lites" with an xml drop in. The magnet sounds like a great idea. Where can I get a thin piece?

oKtosiTe said:

Damaging the protection circuit at the bottom of the battery could get you into trouble...

Click to expand...

Uh oh. What's the worst that can happen? Haha

oKtosiTe said:

Damaging the protection circuit at the bottom of the battery could get you into trouble...

Click to expand...

That doesn't looks like protected battery to my eye, would be nice if OP would clarify what type it is.

c.joe said:

Uh oh. What's the worst that can happen? Haha

Click to expand...

Worst? Explosion, or, if you're more lucky, venting with flames.

I have never had a battery dent like that. I have had the positive side dent slightly but never the negative. That really does not look good

c.joe said:

Yeah I'm using a clicky tailcap switch.



It's a "Tac Lites" with an xml drop in. The magnet sounds like a great idea. Where can I get a thin piece?

Click to expand...

How old is that 18650?
Mine get scratched from the spring, but don't dent like that.

Was your flashlight designed to be used with a 18650 cell? A picture of the inside of the tailcap might shed some light.

Hi Chris. It would appear that the negative contact in the tailcap is what is causing this. This can happen when using protected cells in some lights, as they are longer than true "18650" cells, due to the protection circuit that has been added. When the tailcap is screwed tight, after installing the cell, you may notice that at a certain point, it gets harder to tighten.

One other possibility as to how this may have happened, is if the light has been dropped on end. The momentum of the cell's own weight may be enough to dent the cell upon impact.

From your picture it is hard to tell if the cell has an added protection circuit, or not. Just guessing, it doesn't appear to be a protected cell. If the cell is a protected type, then you may run into problems, as mentioned, as the circuitry could easily be damaged. If the cell is an unprotected cell, this isn't good either as the separator in the cell could be damaged, or the cell could short out internally. In either case, this is not a good situation.

The best solution would be to either smooth out the contact area of the tailcap connector (spring, button, or whatever is used) so as to more evenly distribute the contact force, or trim/file it down a bit so it doesn't protrude as much. You may need to do both. Also, make sure that whatever makes contact with the cell, is not sharp, or pointed.

Dave

there are a few errors in the posts here.

1st: that is not a McKlicky switch (thats a very special switch and not "only a tailcap switch" as Your light has. Also a McKlicky has a spring at the end (stiff but ... there))
2nd: a protected cell has its circuits at the positive side, that here is the negative ...

[edit]
2nd ist wrong, there is no "fixed" position where such a circuit has to be placed ...
[/edit]


but I also think that dent is not good for whatever is behind it - possibly danger ahead.


Your light has
a) some fix(ed) contact point on the end (which You might try to shorten and put a spring on) and
b) is too short for this cell, when screwing the tailcap on, You "produce" the dent
... as 45/70 has typed

yellow said:

there are a few errors in the posts here.

1st: that is not a McKlicky switch (thats a very special switch and not "only a tailcap switch" as Your light has. Also a McKlicky has a spring at the end (stiff but ... there))
2nd: a protected cell has its circuits at the positive side, that here is the negative ...

Click to expand...

Nope, protected cells have protection PCB on negative contact.
http://www.lygte-info.dk/info/battery protection UK.html

Shadowww said:

Nope, protected cells have protection PCB on negative contact.

Click to expand...

yellow, just to point out, there are actually two types of "protection" possible on Li-Ion cells. "PTC' "positive temperature coefficient" protection is located at the positive (+) end of the cell. All Li-Ion cells and lithium primary cells should have PTC protection. Some Chinese cells, especially CR123A primary cells however, do not.

"PCB" protection ("protection circuit board", or "printed circuit board") is mounted onto the negative end of Li-Ion cells only. This type of protection limits the discharge/charge voltage, and usually, maximum current as well.

As for what type of cell the OP has, it really looks to me like the bottom of an unprotected cell. I do not see any evidence of the usual "wrinkle" that is present on PCB protected cells, but it's not really possible to tell for sure, from the picture.

Dave

Thank you everyone for the reply.

I found the battery information.

Battery info:
Model: Sanyo UR18650F 2250 mAh 3.7V
Min Capacity: .2150 mAh Typical Capacity: .2200 mAh Nominal Voltage: 3.7V Size: Max.18.10 x 64.80mm Weight: Typ.47.0g

Here are some additional pictures. I'm just going to throw out the battery but I'm a bit disappointed that it developed into this.





Left side is the head and right side is the tailcap.



Any recommendations for a replacement?

Looks like somebody hit that with a 'center punch' and ball-peen hammer, or shot it with a BB gun.

I don't think any tailcap/spring made that indentation.

Chris

Bullzeyebill said:

c.joe, post a picture of your flashlight. People are shooting blanks here because there is not enough info.

Bill

Click to expand...

My apologies, I thought Tac Lites only made one model.

http://www.taclites.com/Products-and-Info.html

Thanks for the help folks.

No apology needed.

Bill

ChrisGarrett said:

I don't think any tailcap/spring made that indentation.Chris

Click to expand...

You might have typed, while c.joe posted his image,
one can clearly see the "punch" inside the tailcap.

unfortunately, I have no idea what to do, except for using shorter batteries or grinding the center contact down (which might result in other problems)

just a side-note: the postitive side of that battery is also bent ...


PS: thanks for the info that there are several possibilites where the circuit is placed.
I do correct my post ...



[edit]
try to get the interiors of the tailcap out and check, if it could be grinded down from the back
(without damaging anything)
[/edit]

[edit 2]
PROBLEM: the size You mention for the cell is extremely short.
If that light can not be modded to offer at least 2 mm more space for the battery,
a normal one - they usually are longer - will be damaged even more
[/edit]