Li-Ion signs of retirement?

[rizky_p]

Hi, i have several 18650, RCR123 and 14500 li-ion batteries, how to tell that some of them actually need to be retired? What are the signs? I have one 14500 cell that stay charged around 4.1v but can only managed 0.3A on a flashlight whereas other 14500 manages around 0.9A kind of increased internal resistance maybe?. Is this one of the signs?

 

[Fallingwater]

Increased internal resistance definitely is a sign.

If your cells get to 4.2V (CA) very quickly, then stay in CV for ages, that too is a sign.

 

[DM51]

As a cell ages, it will no longer be able to hold a full charge. When the charge is terminated at 4.2V and the cell is disconnected, its voltage will drop.

Dropping to 4.1V (as your 14500 cell is doing) is a sign that it is on its way out. As you have found, it is also now unable to deliver as strong a current as it did when it was new.

You may also have noticed it heating up more than previously during recharging - a sign of its increasing internal resistance. It is now only fit for use in fairly low-load applications.

When it can no longer hold 4.0V (~80% of a full charge) it should be considered effectively dead. You may have decided to retire it before then anyway, as it won't be much use except in very undemanding applications.