I use the same radio. What i do is just open the battery hatch and connect the battery connector cable to a charger and auto-charge it. I do not use the suppiled charger as I tend to discharge and recharge my batteries regularly. I would assume that Futaba suggest to use 200mah to prevent any damage from the battery getting too hot while charging it? I mean, those are casual NIMH cells, I see no reason to not fast-charge them in any way.