Rechargeable Li-ion battery question - I'm confussed

I'm fairly new to the wonderful world of Luxeon LEDs and I am puzzled why my 3 volt 650 mAh protected cells charge to 4.1 volts and stay at 4.1 volts. But my 3.6 volt 800 mAh unprotected cells charge up to 3.9-4.0 volts but settle down to 3.7volts? If a cell states it is a 3 volt cell shouldn't it be a 3 volt cell (within 10%)? I'm sure this has been covered some where here in the past but I didn't have any luck using the search thingy.

Most Li-ion rechargables have norminal voltage of 3.6-3.7V and reach 4.1-4.2 when fully charged. However there are some 3V (norminal) Li-ion rechargable which full-charged voltage should be 3.6-3.7V. Your unprotected cells seem to be 3.0V type if they can not hold the voltage at above 3.7V.

Yes, the '3.0v' rechargeables are supposed to replace primary 123's for cameras etc. But they are slightly fatter, so won't fit in a Surefire L2. However they will fit in an Inova X0. They'll also fit in an HDS U60, but it thinks they are primary cells and tries to draw too much current, at which point they droop and it steps down.
A word of warning: My Pila charger doesn't like them- as they approach full charge they go slowly open circuit, and I suspect they aren't fully charged.
Best to buy them with their own charger IMHO.
HTH.

LeftCoastEddie said:

I'm fairly new to the wonderful world of Luxeon LEDs and I am puzzled why my 3 volt 650 mAh protected cells charge to 4.1 volts and stay at 4.1 volts. But my 3.6 volt 800 mAh unprotected cells charge up to 3.9-4.0 volts but settle down to 3.7volts? If a cell states it is a 3 volt cell shouldn't it be a 3 volt cell (within 10%)? I'm sure this has been covered some where here in the past but I didn't have any luck using the search thingy.

Click to expand...

These 3.0V cells are actually 3.7V cells with an electronic circuit, which reduces the voltage under load.
I have the same findings with my cells. It has been said, that the voltage drops to around 3 volts under load. But I'm not able to confirm that.

I use 'em without any problems in my Gladius, L4 and ALX-352.

I found a way to proof that these 3.0volt cells really work at 3.0 volts.
Today I recieved a "Ansmann energy-check LCD" batterietester.
I was aware of the fact that its actual not for 3.7v rechargeable cells, but I tried. It displays the charge level in percent and the voltage under load.
For a normal 3.7v cell (4.13V open circuit) it shows around 3.8v.
And a fully charged 3.0v cell, which shows around 4v open circuit, is measured exactly at 3.00 volts!!! Nice!
Thanks for reading!
Rico

Rico, thanks for the information. I was going to set up a "load" test using an incandescent bulb and my fluke multi-meter but had not found the time to do so. That battery tester is a slick little unit. I might have to get one if I can figure out a way to justify the expense to my wife. It's tough enough explaining to her why I need another flashlight every 3 to 4 months. Last time I ordered a new flashlight she walked away mumbbling someting about me having a flashlight fetish.
Ed

Man! They don't understand us.
This Ansmann tester is really nice. All other testers (I found) on the market a really crap and/or are not for CR123/CR2s.
If you don't want to spend so much money for a tester, you should get a feel for testing the cells via voltage. If the cell is ok, it should give one good results. But if the cell is older, I found that it's got high voltage but no capacity. That's why these testers measure voltage under load.

Greetings to you wife!
Buy her a pair of new shoes and you a battery-tester!