Suntech ST4940 standalone GPS tracker has a rechargeable (3000mAh/3.7V) Li-Ion battery that can life up some days with a single charge, contact with Suntech to know the exact duration times of the ST4940 battery. To protect the asset driver or the person that used ST4940 NB / IoT GPS tracker, Suntech GPS tracker has a "panic button" that generates SOS emergency alerts and ST4940 send this alerts to a predefined mobile phone. 3 GPS tracking modes accept Suntech ST4940 GPS tracker to locate your mobile asset in real-time: (from the Suntech online server, sending commands with SMS text messages, using an external tracking management platform "edit default IP/port"). Suntech has designed ST4940 NB / IoT GPS tracker to cover different requirements in the GPS asset tracking (with self-power or without self-power), but also is a valid alternative to use in the GPS personal tracking and lone workers tracking. To control that Suntech ST4940 GPS tracker always has the battery level that you need, offers "low battery SMS alerts", when ST4940 NB / IoT GPS tracker detect that the battery excess of the preconfigured limits, starting to send notifications through "SMS alerts" that you receive in the mobile phone.