Mercury 115 EFI 4-Stroke Charging System

colbysmith

colbysmith

Active member
I finally took my boat in to the shop to have the engine gone over...just to make sure it's working like it should. (And it also appeared to be having some charging problems.) Found out everything on it is working like it should, except the charging system. I've been told that the problem is with a fuseable link wire. Anyone know anything about the charging system on this outboard, and what would cause this wire to go out? It's currently on backorder from the factory, but I'm hoping the shop can find one locally, so I can get it fixed in the next week. Colby
 
My first question is why did the fusible link blow? Was there a short or overload? (rare on an outboard).

A fusible link (usually 4 wire sizes smaller than the primary wire, with special insulation, which will not burn or melt)--is there to protect the alternator. But it can be replaced by certain types of fuse. You would want a slow blow, maxi fuse, rated for the same current as the fusible link. You can then carry a spare fuse.

First find out why it blew.
 
Well, I found a fusable link here in my little community.... and now have the boat back. I'll replace that wire myself, as it doesn't look to involved. Speaking with the local mechanic, he said just tapping the batteries with the battery wires reversed could do it. THe wire is there to protect the delicate electronics of the newer engine systems. It's a 100amp fuse inside the wire. That's a lot of current in my mind. The shop computer they checked my engine on said the issue happened at 59 hours, I have 61 on it now. I thought maybe the person that replaced the batteries before I bought it from the old owner might have caused it, but I'm sure I've put more than 2 hours on the boat now, so not sure what caused it to blow. I've been doing some work on the boat with electronics. I've also switched the battery switch a few times, but never to off with the engine running. Only between battery 1, 2 and both. Perhaps I need to stay away from switching batteries with the outboard running. And I believe once I ran the engine with the shorepower charger still charing the battery system..... perhaps that too could have blown the fuse. Just don't know. But in any case, that little sucker was $74, so hope it doesn't happen again. (But in marine costs, that's cheap....) Colby
 
If your battery switch isn't the "make before break" kind, then it may be unsafe to switch between 1-2-both positions while the engine is running. Unless it's make before break, the motor output will momentarily be floating while the switch is between contacts. Someone else will have to back up this theory.
 
Yes, the above is correct. You will have to check the switch to see if it make before break. --Running the charger and the engine at the same time should be OK--but I would not do it on a regular basis....
 
I think I'll check that switch then. The battery switch on my old boat was bigger than the switch on my C-Dory, and I know the old one was what you are calling make before break. Of course, a larger one wouldn't fit in the same spot, so I may just need to learn not to move the switch with the motor running. (But I would like to be able to charge both batteries, one at a time without turning the motor off... oh well....) Another thing. I do have an anchor windless on this boat. But it has a 50a cb, so I would think it would trip that long before blowing out that 100a fusable wire link. Colby
 
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