Just entered into the world of li-ion

[signal 13]

I just ordered my first li-ions to convert my M3 and 6P to rechargeable. I was a bit reluctant with all this talk about "vent-to-flame" stuff. But after doing some reading I got some protected AW and Wolf Eyes cells and a Pila IBC charger. I also got some LF HO-4 and HO-M3 bulbs. It got a bit pricey so I hope it pays off!

One question: How do I test my batteries? Can any multimeter do the job or what? How much do these bad boys cost?

 

[SilverFox]

Hello Signal,

You can use a voltmeter to check to see if your cell is fully charged and it can give you an indication of the internal resistance of the cell. Your cell should come off a "proper" charger at a voltage of 4.2 volts. As the internal resistance of the cell increases,, through age and use, the fully charged voltage will drop off. When it drops below 4.0 volts, it is time to recycle the cell.

Another test you can do is to check the capacity of the cell. If you know the current load on the cell, you can check the runtime and convert that to capacity. This test can be as simple as a runtime test in a flashlight, or you can invest in a battery testing device like the CBA II from West Mountain Radio. I believe the CBA II runs a little over $100.

Tom

 

[Flipside]

SilverFox: I'm in the same boat as signal 13, but confused by the concept of a 3.7V (per the rating on the nameplate of the cell) being charged to 4.2V. I understand that the charger should stop at the 4.20V, and that this value should never be exceeded. However, when you say that the cell should be recycled at 4.0V, I'm stumped. It's only rated for 3.7V...

 

[mdocod]

Hello Flipside,
When the cell will no longer hold ABOVE 4.0V on a fresh charge it should be recycled. During normal use it will cycle in the 3.0-4.2V range.

a li-ion cell operates across a range of voltages during charging and discharging. The 3.7V rating of the cell is representative of somewhere in the middle of that range.

 

[LuxLuthor]

mdocod really answered your question, but a good way to understand the 3.0V--3.7V--4.0V--4.2V questions is to compare it to rechargeable Nickel Metal Hydride.

NiMH has a "nominal" value of 1.2V (like Li-Ion 3.7V number)
NiMH charges up to about 1.5V (like Li-Ion 4.2V)
NiMH can be drained down to 0.9V (like Li-Ion 3.0V)

Over time, NiMH will deteriorate, and lose its capability to store the proper charge, so if a fresh charge results in a drop within minutes down to 1.2V (like Li-Ion 4.0V), it is approaching the end of its life.

 

[Flipside]

mdocod and LuxLuthor:

Outstanding! Thank you for your input.

 

[MrAl]

Hi there,

I get rid of my old Li-ion cells when the flashlight runs down so fast that it becomes
annoying to have to keep recharging it.