Run the Garmin Instinct Solar GPS Smartwatch by using sunlight to power the battery. This GPS smartwatch has a solar battery to provide unprecedented battery life when exposed to the sun. As a result, you can spend less time charging and more time exploring. Alternatively, switch to the smartwatch mode to use this device for up to 54 days. Once it’s charged, there’s so much you can do. First, it incorporates a heart-rate monitor that monitors how hard your heart..