Details
ST301010-001 SkyWave SG-7100 Auto Car Charger, DC Adapter
The DC adapter connects to the power/serial cable and provides power to the terminal from a 12 V cigarette lighter port in a vehicle.
Automotive cigarette lighter ports are either switched (powered only when the ignition is ON) or un-switched (always powered).
If possible, it is easier to use an un-switched port(or have one installed by an auto technician) so that the terminal can remain powered when the vehicle is not running.