Turnigy Accucel-6 USB Adapter

http://www.dealextreme.com/details.dx/sku.12618 It may give a tips on how to use the 3pin Temp port for USB, it is similar kind of charger.

The temperature input is the serial data out, but you must invert the signal before you bring it to pin 2 of the serial connector of your PC. Ground is the one furthest from the DC in, bring it to pin 5 of the serial. The pin closest to the DC input is +5V, useful to power the signal inverter with. Seems to work nicely that way.

Pinout seen from 12V connector:
+5V
Temp input / Serial output
GND
This is no USB port, it needs an Serial-USB adapter.