Strange Trustfire protected 18650

[hyperloop]

Hi all, have a Trustfire protected 18650 which seems to be acting strangely, chucked a pair of them in the WF-139 charger last night and left them to charge, this morning when i woke up, about 6 hours after i put them in the charger, one indicator light was green and the other was red.

Took them both off to check and one cell was 4.15v which was what i expected, but the other (the one showing red on the indicator light) was 3.91v and the cell felt pretty warm but not too hot to hold.

Is there anything wrong with the cell?

 

[jasonck08]

Re: Strange Turstfire protected 18650

Some of my chargers heat up quite a bit, and this causes the batteries to get warm. The batteries by themselves should generate little or no heat if they are being charged at like .5C or less. I'd throw the 3.91 cell on the charger and see if it charges.

Just a word of caution, I probably wouldn't go to sleep with a cheapo charger and set of lithium batteries charging, for fear of something bad happening in the middle of the night.

 

[kramer5150]

Re: Strange Turstfire protected 18650

Somethings wrong with the 3.91V Cell. An overnight charge should have been plenty of time for your WF-139 to completely top off the cell.

My WF-139 does get warm, and some of that warms up the cells slightly.

I have had duds do exactly as you describe. They get warm to the touch, seem to take WAY longer to charge, and never come close to 4.2. I am not sure exactly what was going on with these cells. But I didn't bother keeping them. I think you would be wise to do the same.

 

[hyperloop]

Re: Strange Turstfire protected 18650

Thanks for quick replies guys, to clarify, it wasnt the charger that got warm, it was the cell, but i dont think i want to take any chances with this cell so in the bin it goes.

 

[hyperloop]

Forgot to mention that i popped the defective cell into my Jet III Pro ST just to see if it would light up.

It did but there was definitely something wrong with the cell.

On minimum: no problem

On maximum: it would light for about half a second then the light would go dead.

On slow strobe: no problem

Could any more knowledgeable CPF-ers care to speculate on what might be wrong with the cell? It would be good to know as the cell was working fine till recently, all charge cycles were terminated once the light in the charger went green (of course at times, this might be an hour or so after the light went green) and the cells were never run till the protection circuit kicked in.

 

[VidPro]

Re: Strange Turstfire protected 18650

I have had duds do exactly as you describe. They get warm to the touch, seem to take WAY longer to charge, and never come close to 4.2. I am not sure exactly what was going on with these cells. But I didn't bother keeping them. I think you would be wise to do the same.

That right there is one of the things that happens when they are AGED dead bad and Dangerous. dangerous because they are not "accepting" charge, and the energy going in is just turning into heat.
if you fast charge cells like that they can pop on you.

getting hotter than normal
not reaching voltage when they should be charged by then
Self discharging (because good li-ion has very little self-discharge).
reduced capacity
reduced runtime, or inability to output good current.

your description is very good to indicate the issue.

Can happen from Just:
age and or cycles (even if YOU havent owned it long it may have sat on a shelf for long before you bought it)
too Deep of discharges, which will ruin the cell
any possible reverese charges, which would be really bad fast, and cant happen with protected.
charging higher often and it staying quite high, or even abnormally high .
Damages to the roll, hard drops, even say in shipping, beings some sellers still cant ship rechargables with conciderations for the post office playing "basket Package" with your shipment.