I have the isolator and haven't noticed any issues until this week. As I understand the blue light should be on when engine running and it's open to charge. I noticed mine is on with the key off. My second battery is not on the ignition but does have a switch panel and everything was off. This week my amp kicked out like a weak battery. My daughter took it for a few hrs and she likes her music so I Thought something was wrong with amp but as I was cleaning and opened the hood I noticed the blue light on. Is this normal and do I possibly have my second battery going bad, bad cell??