My 2014 Escape recently needed a new battery. After getting to the battery (30-minute job), I got to the negative terminal and saw that it had a lot of corrosion...no big deal, I've seen that on countless vehicles. What I found connected to the terminal was something I've never seen. There was some kind of device attached to the terminal, with its own two-wire cable and connector. I was careful to clean all of the corrosion and not damage whatever this device was. It all went back together OK (another 30-minute job) and all runs well. Can anyone tell me what the device is on the terminal?