eForCity&reg; Vehicle Car Charger Compatible with Garmin n&uml;&sup1;vi 1390T Portable GPS Vehicle Lighter Adapter (12~24v DC). Smart IC chip recognizes a fully charged battery and automatically switches to a saver mode. GPS can be used during charging.Short circuit protection. NOTE:When using this charger for GPS device, GPS device might restart with computer mode; after less than 10 seconds of synchronization, GPS will start with GPS mode with charging from the charger. LED charging indication. Plug never heats or overcharges the battery.