18650 got hot on charger?

I got 2 of the Tenergy 18650s 2600mah with PCB from battjunction, and have been using these without any problem at all.

I got 4 more of which 3 registered around 3.6 - 3.8v on my DMM, and one 0.00.

So, I put 2 of the good ones into my charger (a cheapo multi charger)
(5.5V / 350ma)

I came back 2 hours later to check on them, and they were HOT!
One of the cells was almost too hot to touch, and the other was less.

Both measured 3.96V while still on the charging cradle hot
Now, one is 3.69V and the other 3.79V

My original 2 batteries never did this.

Am I missing something here? I am a newb at Li Ion chemistry, but this is bad right?

Hello Kyle,

Yes Hot is not good. Cells get hot just before the rapidly vent with flame.

Move them outside to cool off.

Now, the voltage of your charger seems to be too high. Li-Ion cells should only be charged to 4.2 volts. 5.5 volts will cause them to rapidly vent with flame.

I see that these cells are protected. Most protection circuits only protect to around 5 volts. 5.5 volts may have toasted the protection circuit.

I would suggest that you contact the vendor and ask for replacements.

Tom

Hi again,


Yes i agree, 5.5v is wayyyyy too high for Li-ion cells. You need a special
charger designed for Li-ion cells to charge them, not any old charger.
I would not be surprised if both cells are ruined or dont last long even when
used with an appropriate charger, if you even dare use them anymore at all.

The charger is made for 18650 Li Ions. In fact it is a Tenergy charger
The 5.5V / 350ma is whats on the back of it.

Like I was saying I have two batteries just like these that have charged 10 to 15 times on this charger with no problems at all.:thinking:

Do you think it has something to do with charging 2 at a time?
Possibly different voltages to start with?

Hello Kyle,

It sounds like something is wrong with the batteries themselves.

I still don't like a Li-Ion charger that has the potential to charge above 4.2 volts.

Tom

I imagine the 5.5 V 350mA is the input power, does the charger have a wall wart?

Yep, it reads the same on both the cradle and the plug.

here is the link

http://www.batteryjunction.com/tlunlichfor1.html

Dr.K, That is a DSD brand charger that other people have discussed on this site. I have the very same one from DX. The 5.5V (actually 5.9 V measured) is only the open voltage and isn't a problem since the closed charging voltage drops due to current limitations. My 18650 batteries never even get warm with so little charge current from the stock wall wart.

BUT, that craddle has live CR123A contacts on the sides that will short 18650 batteries if the plastic wrappers are damaged or removed. Check to see if that may be the reason your battery is heating up, which can happen even if the charger is not plugged in.

Thanks yenster,

Well I'll be damned!
There is a small slit in the side of one of these cells right where the horizontal contacts are!

I charged that one to 4.16V by itself. It held the charge over night.
I see now that by putting 2 of them in together it forced the wrapper to slit on that metal and cause a short.

I'm glad I checked on it before

Thanks everyone for your help :thumbsup:

Well it's good to hear that you found the problem. I think that Ultrafire discovered this same potential problem on their WF-139 charger, and that's probably the reason it comes with its CR123A contacts disabled.