Go to RadicalRC.com ( http://radicalrc.secure-mall.com/shop/ ) and to their battery department (when you click on the battery department, the battery selections will appear below but it will look as though the page did not change. Select the type battery you are looking for and another screen will pop up with a large selection of batteries). Any battery that is larger (capacity) than your RX and TX battery will work. They have a selection of all shapes and sizes (physical) and sizes (capacity).

I up'ed the capacity of all my RX batteries using 5 cell 1200 mah NiMH's from my local hobby shop too. The 5 cell 1200 mah NiMH are light and work just fine. For the TX, I have 1650 mah 9.6 volt packs, but these are NiCd packs. My larger planes, Venus II, Excelleron 90, and Tiger 120 all have two battery packs each, two switches (independent systems) plugged into two separate RX channels.

If you stick with four cell RX and the standard 8 cell TX batteries, you should be just fine with the wall wart charger. If you move up to the 6 volt (5 cell) RX packs, though, you will need to update your charger to one that will handle the 5 cell packs. Sirius, Triton, Ice, among others are good chargers for those battery packs.

I might add that Dave Thacker, the owner of Radical RC has a very large FAQ section on batteries. It is great reading because he is both frank and up front about battery packs of all sorts.

DS.