Charging cells in series vs independently

I recently took a look at the Maha C777PlusII charger, and it looks to be quite an interesting beast - capable of charging up to twelve NiMH at one shot at 800mA fast charge current!

However I'd like to ask, is there a disadvantage in charging the NiMH together in series like the C777 does, as opposed to independently controlled channels like the C401FS has?

More important, is there anything I should be aware of regarding lithium ion cells? The Maha claims to be able to charge lithium ions/lithium polymer in SERIES - doesn't this seem just a little bit DANGEROUS?

Charging a single cell is preferable to charging in series.

When charging in series, the two cells may not have the same state of charge, and one will become fully charged before the other. You'll either end up with one cell undercharged, or one cell overcharged. If the charger terminates fast charge as soon as one cell reaches full charge, and then switches to trickle charge, then the disadvantages are reduced.

If you are talking about Li-ion's, then I'd be more concerned. I'd hope that the charger monitored the cell temperatures in order to avoid overcharging.

Steve K.