On the whole it's not recommended to charge multiple Li-Po cells at the same time without proper monitoring and cell balancing circuitry. The short explanation is the cells don't all drain and charge at exactly the same rate and if one cell fills up first, it can cause it to start draining into the emptier one which is a situation to be avoided at all costs.
i have/use a balancer for the 14560 packs shown in my post with the 3D printed sled. I am a green horn with arduino, but i have been making my own 2+ cell lipos/lithiums, for the better part of 10 years. i hate doing it. making packs is a hassle and a half that THAT is something to avoid at all costs :). and while you don't need balancers, at all. period. you don't. the real reason to use a balancer is if one of the cells is on its way out, a 7.4v charger will keep pushing voltage till it gets to the right 8.2v smart charger cut off point. if one of the cells is bad, the good cell will over charge and puff up, and shoot burning hot exposed lithium. hot enough to melt aluminum. or what ever toy/gizmo you have the pack in. and because each cell is charged independently. it may decrease charge time. balancers charge faster/safer. not any better. i wish they made them for my 7.2v packs for my 1:10 cars. A NiMH pack with a dying cell will get HOT during charging. if they had balancers, just the cell that was not as good as the others would get hot. if the cell was dead, the charger wouldn't work. Same with Lipo. With Lithium, A dead cell is safer than a bad one. and if you know the order of cell charging in a balancer, you can replace the bad cell. the balancer will simply shut off (maybe with an indicator light) when it gets to the bad cell.
they are for Lipos mainly,
for 14560 and 18650, or any pcb cells,... 99.9 times it's whatever. Unless you're dell computers. they must buy the worst 18650s. they are always int he news for melting people's laps. a 7.4v lithium smart charger. read the specs, make sure the auto shut off is somewhere tween 8.2 and 8.4v. some 7.4v smart chargers only push 7.4v (found that out the hard way) , which will charge your batts to about 30% capacity.