I have had an ultrex on my boat since last year using a marinco plug. Batteries were about 6 years old and noticed end of last season and beginning of this season they weren’t lasting as long as before. They were 27 series and a couple weeks ago replaced with 31’s. Yesterday I fished the St.Lawrence River so was on the trolling motor pretty good and it lasted an 11 hour day with no drop in performance all day. Got home last night and went to charge the batteries and when I went to unplug the trolling motor (like I always do before charging) the plug won’t come apart. It doesn’t smell burnt at all but I’m pretty sure it got hot and is melted together. I plugged it in yesterday when I got to the river so I know it wasn’t like that before. I’m going to tear into it tonight but my question is did the 31 series batteries have anything to do with that or did it just so happen that I ran it harder than normal and the plugs time was just up and it needs replaced?? I’ve read that these plugs aren’t the best but I have never had this issue with it ever with any of the trolling motors before and I used to run 31’s in the boat before I had the 27’s. Is it possible I just had a poor connection in there and because I ran it hard in the current and the new batteries were so strong that it found the weak link and I just need to clean the connections once I get it apart??