Got a 2 bank charger for trolling batteries. Last time i went to the lake i started having issues. I left the charger on overnight when i got back last time and it was pretty warm the next day when it should have been completely charged. Yesterday when i was checking it out it showed battery 1 with connection issues and battery 2 charged. I switched leads and it still showed battery 1 with connection problems. Any ideas or time for a new charger? Its closing in on 10 years old.

If it still showed a problem after switching batteries, the charger is bad.

Time for a new one. I had one bank on mine do that. Called Minn Kota, no replaceable parts.

I just went thru this. Red light indicating bad connection. It was a bad fuse.

When I first checked, I moved the fuse holder that looked bad and it fell apart. Aha, I thought. That was the problem. I replaced the fuse holder and fuse and reconnected only to have the same problem indicating. After changing things around determined that another connection was bad. I took the removed new fuse and put it in one of the other two on the other bank and red light went away. The original fuse was ok (it was the connection that broke) so I put the original fuse I had removed to the other one and viola, it works.

I hope this makes sense. Short story, check fuse first before buying a new charger. My charger is old and is still performing as it should with the new fuse and repaired connection.