RE: batteries and charger for JR SX3 ?
The biggest thing when it comes to any battery.... is that you should cycle the batteries before using them weather it is NiMH or Nicad. This will condition/prep. them for use. Most say 3 to five times. This is where a good charger comes into play. It has been my experience with the style of charger you are looking at..... they do more harm then good. Trust me on this. Spend the money on a good charger that can "do it all". All of your rechargable batteries will love you for it!
With 2100mah (provided they are fully charged) batteries, the last thing I would worry about is running out of power!!!!! With my 1500mah cells, I can go all day with my XS3.... and not worry about.