RE: Rhino 4900
Charging as 10s or 2 5s depends on the charger.
My FMA cellPro 10s charger charges two 5s pack at same time, utilizing the discharge wires (forming the 10s), and the two balance connectors (one from each of the 5s). The remaining two discharge wires (again from each of the 5s) are connected during the charge (as well as during flight).
Technically I could permanently solder the 5s into a single 10s pack and many pilots are doing it. I did not do it though because the 4mm bullet connectors could wear out (e.g. due to electric arc) and I have some redundancy with two bullets from each 5s.
I also disconnect the connecting discharge wires after the flight. The pack in that configuration will not be used again unless charged.