The Stovebolt Site Forums The Shop Area The Electrical Bay Primary Circuit Protection?

My 54 3100 has been converted to 12V and has a one wire ALT. I want to add some protection to the circuit at the BAT terminal on the ALT. A friend gave me about 5" of fusiable link wire which looks to be 10 gauge (I have 10 gauge wire in this circuit). The fusible link wire seems to expire within weeks or months of use (no smoke, but no longer allows current to reach the BAT terminal on the ALT. What might I use to protect this circuit, as by the nature of a one wire ALT, it is HOT all the time. The ALT is rated at 63 amps.

Please help.

Most problems with fusible links happen where the connection is made to the regular wire. Crimp connectors usually aren't good enough connections, resulting in heat buildup and fuse link burnout at the connection. I like to strip about 2" or so of insulation on both ends of the link, and a corresponding amount on the conductor I'm attaching to, do a TIGHT twisted connection, followed by a quick, careful solder job. Then use a piece of heat-shrink tubing to insulate the connections at both ends. You could also solder a terminal lug onto the fuse link where it attaches to the alternator, and just do one twisted connection to the wire going to the battery.

If the link fails after installing it that way, you need a larger-diameter link. Surge current from the alternator right after starting can go extremely high, and the fuse link is doing what it's supposed to do, interrupting what it sees as a short circuit. You could also install a high-capacity fuse holder, with a 60 or 80 amp fuse. Those are on some newer cars instead of fusible links.
Jerry

Mr. H. Lincoln, thank you for your reply. You nailed it, the problem was right in the terminating connector at the ALT. I will solder the connector.

Of course any tips on soldering would be appreciated. I've seen/have connectors that can be soldered, however I wonder how to solder throught the plastic insulator?

I did look into the high-capacity fuse holders....I'm REALLY hoping I become a fusible link/soldering wizard fast. I couldn't believe the prices.

Thanks again.

Cut the plastic insulator off and replace it with shrink tubing after soldering. Also cover the splice end with shrink tubing. Be sure to put the tubing on the wire before soldering.

Yep, Cletis got the idea! Slip one or two pieces of heat-shrink tubing over the fuse link, far enough away from the connection that the soldering operation won't shrink it prematurely, trim the insulator off the terminal lug with a sharp knife, crimp the connection, and heat it up with a pistol-grip type soldering gun, the higher the wattage the better. Pencil-type irons just don't have enough power to do a quick, clean job of soldering big wires. The connector should be heated enough to melt a small-diameter piece of rosin-core (not acid core!) solder by just touching the connector- - - -DON'T melt the solder with the gun and expect it to flow into the connection- - - -it'll just pile up on top like chicken poop! A good solder joint should be smooth and even, with the solder penetrating evenly all the way through the connection.

If you keep the heat on the joint too long, the fuse link will melt- - - -that's what it's supposed to do when the current gets too high. Once you've got a good solder joint, let things cool down, slip the shrink tube over the connection, and heat it with a butane cigarette lighter or a heat gun. It will shrink to half its original diameter and insulate the connection you just made.

Good luck!
Jerry

Thanks for the explanation. It's easy when you know how.