What Battery should I use?
When in doubt, use your airplane manufacturer's recommended battery. This is generally a good starting point, although with experience you will probably have your own ideas about the best battery to use. Here is some basic info about battery types.
There are three main types of batteries currently (no pun intended) in use for electric airplane motors. These are Nickel Cadmium (NiCad), Nickel Metal Hydride (NiMH) and Lithium Polymer (LiPo).
NiCads are the oldest generation of these batteries. They pack more power but are heavier than the NiMH.
The NiMH voltage (power) tends to fall off fairly fast during the flight. The wonder batteries LiPos have great power for little weight and hold that power well throughout the flight.
However, they tend to be much more expensive than NiCad or NiMH. Again, go with the recommended battery, you will have time to experiment after you learn to fly.
Note that more cells in the battery means more voltage, which means more power.
Power (Watts) = Current (Amps) x Voltage (Volts) Again, go with recommended number of cells for now.