WARNING: This page is about a different car, the 2015 Fiat 500. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Intelligent Battery Sensor (IBS)
Courtesy of CHRYSLER GROUP, LLC
The Intelligent Battery Sensor (IBS) is mounted directly on the 12 VDC battery's negative post. The battery post clamp nut is a captive nut and the stud will break if the nut is removed.