Jetson tx2

i want to apply power to the tx2 board with a battery,
because the charging line is inconvenient because of the wire.
Do you have any specifications to check when buying a battery?

Nothing specific, but you must make sure that regulation is quite good. A regulator is advisable even if the Jetson is the only thing on the battery. If anything else is on the battery, especially motors, then you’ll require even better regulation (and in part protection against an inductive load’s power spikes). So a lot depends on what else will be powered, even if it is being powered via a USB port on the Jetson (a keyboard or mouse does not really count since they draw so little power).