You must have a charge controller in Li-Ion between each voltage point because overcharging a cell is asking for trouble.
Sealed battery pack, you can put a little controller in there with it. Loose cell, you either give up some capacity and add some cost by putting a controller in each cell, or you trust that the controller in whatever charges it is good. Bare cell, good charger, fine. Bare cell, iffy charger, you might get the blame when the cell goes up. Thus it's very hard to find good bare cells.
You must have a charge controller in Li-Ion between each voltage point because overcharging a cell is asking for trouble.
Sealed battery pack, you can put a little controller in there with it. Loose cell, you either give up some capacity and add some cost by putting a controller in each cell, or you trust that the controller in whatever charges it is good. Bare cell, good charger, fine. Bare cell, iffy charger, you might get the blame when the cell goes up. Thus it's very hard to find good bare cells.