arduino board is hot when using xbee with battery

Why is the arduino board connecting with xbee hot when they communicate with each other using battery?

Why is the arduino board connecting with xbee hot when they communicate with each other using battery?

Sexual attraction?

Where is the board getting hot? What kind of battery? What voltage?

Hi, PaulS,
Thanks for your kind reply.
I use two xbees to create a wireless network. One is set up Coordinator AT, another is Router AT. Then I configure Router to send message to control led in the Coordinator board. The voltage of battery is 12.3V. after I offer power supply to two arduino boards, the part of board in the middle of serial port and external power port is hot.
Another porblem is that I configure Router blink led in coordinator every 3 seconds, but sometimes the lasting time of led turned off excesses 3 seconds. What's wrong with it? What happens during communication?

The voltage of battery is 12.3V.

The Arduino is a 5V device. It has a voltage regulator that can convert the input voltage to 5V, by turning the excess to heat.

The amount of heat generated depends on that you are powering (how much current the device(s) draw). XBees draw a lot, so there is a lot of heat generated.

Change to a lower voltage battery - something in the 7.5V range, to require burning off less excess voltage/current and make your Arduino happier.