kind of same question you just asked on another thread. but this time I have a bit more info.
What you need for your b6, or other rc charger is an adapter to charge or discharge one cell in your string through the jst plug.
Take a male jst plug, and strip out the black wire and the red wire, by pulling that pin out of the plug. Then attach plugs on the other end of your wires, so they can plug into the main output wires of the rc charger.
set your charger to 1s and non balance charge, and now you can charge or discharge one cell through the jst plug. set the charger to 2 amps max, so it doesn't over load the balance wires. Your chargers main wires are now able to plug directly into any two contacts on your jst plug using those bare male jst pins. Connect those bare pins to the pack, then using the not bare plug on the other end, connect to the charger. never have those bare pins powered up.
Like I said in the other thread answer, any two contacts on your female jst balance plug is one cell in the string. Cell one has the negative wire, usually black, and the next pin on the plug is its positive. To get at cell two, the next two pins on the plug, and the next two after that is cell three, and so on.
Using this method, you can charge or discharge one cell with any device that works, 5v cell phone power supply, a turn signal light bulb, etc. But of course you get much more control with an RC charger.
You could also, pretty easily, run a balance charge on the 5s pack, if its disconnected from the rest. But I took to single cell charging to balance my packs because it is quicker, when just one cell is low. Quicker to just charge one cell, than discharge 4 cells, then begin to charge all 5 to same level.
