Just to clarify, I think Eugene means each cell should get its own charging circuit. There are lots of chargers that can charge multiple cells at once -- but each has its own charging circuit.

I think the key phrase to look for is "independent charging circuits".

I strongly agree with Eugene. If you have one mostly dead cell, and one mostly charged cell, you can't get a good result if both are charged with the same circuit. Either one is undercharged, or the other is overcharged.

There are also other issues with chargers such as charging too fast and basically cooking the cells.

This review on CPF breaks some of the better ones down:

http://www.candlepowerforums.com/vb/showthread.php?t=70935

-john