12v Jetson battery: how to connect in safe manner?

does anyone have simple instructions for safe way to connect battery?

I did not find 12v battery with

2.55.59mm barrel + centre

Check out http://elinux.org/Jetson/Jetson_TK1_Power#Powering_the_Jetson_TK1_board_with_a_battery for important information about the range of voltages that the Jetson can accept and the kind of batteries to use.

One can use a barrel plug terminal block like http://www.pololu.com/product/2448 to wire it to the battery with relative safety.