My favorite cells

[etc]

The one on the left is AW 18500 protected cell, the others I presume require no caption.

 

[fireguy]

The one on the left is AW 18500 protected cell, the others I presume require no caption.

If I can ask a stupid question, what is a "protected" cell?

 

[etc]

With potentially dangerous Li-Ion, there are no stupid questions...

As I understand it, in a nutshell, there are two problems: You can overcharge a cell, secondly you can overdischarge it. The latter means you destroy the cell, The former can do same although it can also mean risk of fire.

What 'protected' does is it adds a circuit to the head of the cell which prevents it from charging above 4.2V and below (I think 3V?)

the disadvantage is that in this 2x18500 lite, the power just suddenly goes out, like someone cuts off the switch in a room. Not a good choice for tactical situations. Plus 3x123 has longer runtime with a very long tail, but 18500 gives you free lumens.

 

[spencer]

A protected cell means it has a circuit in it that prevents over discharge usually down to 2.4 volts and over charge to about 4.2 volts. With lithium-ion batteries, if they are over charged or over discharged they may lose most of their capacity and not work very well.

EDIT: etc beat me

 

[fireguy]

With potentially dangerous Li-Ion, there are no stupid questions...

As I understand it, in a nutshell, there are two problems: You can overcharge a cell, secondly you can overdischarge it. The latter means you destroy the cell, The former can do same although it can also mean risk of fire.

What 'protected' does is it adds a circuit to the head of the cell which prevents it from charging above 4.2V and below (I think 3V?)

the disadvantage is that in this 2x18500 lite, the power just suddenly goes out, like someone cuts off the switch in a room. Not a good choice for tactical situations. Plus 3x123 has longer runtime with a very long tail, but 18500 gives you free lumens.

That makes sense. Thanks. Does that add much to the cost of the cell? Would other batteries benefit from this or do their different chemical makeup mean it's unnecessary?

 

[spencer]

Other cell chemistries do not need cell protection. It doesn't add a significant cost to the cell.

 

[etc]

Only problem is, you can drop the cell just right and damage this circuit.