The Stovebolt Site Forums The Shop Area The Electrical Bay Hook Alternator to Battery or Starter Post

-Does it really make a difference whether I hook my one wire alternator to starter post or directly to the battery?

-Either way, I was thinking of using a 10ga cable with a 12ga fusible link. How long a piece does the fusible link need to be?

Connecting directly to either the battery or the starter cable connection will charge the battery, but the ammeter will not function if there's still one in the circuit. Depending on the capacity of the alternator, a 12 ga. fuse link might not be heavy enough. A high-capacity alternator like a 75-100 amp model can produce enough surge current immediately after starting to overload a fuse link that size. The link only needs to be a couple of inches long. Make sure it's very well crimped, or soldered into the charge lead. Any resistance in the connection will cause it to heat up and burn in two, which is what it's designed to do in case of a bad short.
Jerry

-Hi, thanks for the reply. It's a 65amp alternator, so what gauge fusible link should I use?

-I was told the Ammeter might not work as one would expect if using a generator, but that it will still show some kind of trending; am I wrong?

Stay away from fuse links - Either put in a fuse block and fuse (I think 75 amp to start maybe more) and carry a spare.

OR put in a circuit breaker.

How do you repair a link 20 miles from howhere??

Dan Bentler

Wirenut, Western Union splice, jumper wire, or a piece of clothes hanger wire. It's called a shade tree fix.

Virtually every car that's been manufactured since the 1960's has several fuse links incorporated into the harness. They just don't burn out unless there's a massive short as long as they're sized right.

Jerry

carrying a spare fusible link is just as easy as carrying a spare 75 amp fuse, and would be much easier [and cheaper] to find in the first place

Bill

"They just don't burn out unless there's a massive short as long as they're sized right."

Jerry


So if I am using a 60-65 amp alternator, what gauge fusible link should I buy?

I'd run a 10 gauge, which should prevent a wiring harness fire in case of an accident or a dead short of a major component like a fuse block feed wire, headlight feed, etc. and still carry the full output of the alternator. They're usually available in the electrical "help" section of most well-equipped parts stores like NAPA, quite often with a round lug terminal made onto one end, and a splice connector to complete the circuit to the ignition switch, ammeter, alternator output, etc. Just be sure to get a VERY good electrical connection where you make the splice to prevent overheating of the connection from resistance.
Jerry

10ga fusible link it is then. I was thinking of soldering the sections together and sealing them with heat shrink.

just don't get carried away with the solder, too much is worse than not enough.

Make a good twisted connection first, wrapped tight with pliers. (Look up "Western Union Splice") Then do the soldering job quickly, or the fuse link wire will melt and fall apart. That's how it protects the circuit- - - -it has a much lower melting point than copper. The shrink tubing is a good idea- - -you can shrink it with a match, a heat gun, or a quick wave-over with a Propane torch.
Jerry

Is there an equal or better way to connect the two wires together than to solder them. It for sure makes sense to not hold the solder gun on the fusible link for too long.

There is a tape like solder that you can wrap around the connection and hit it with a torch kinda like shrink wrap. I just did a quick search and could not find any. Maybe it has a real name that escaped my attention when I saw it used a couple years ago. It melts really quick so you should be safe in not overheating your wire.

Actually, a very hot soldering iron or gun is the answer. I used to use a Weller 250 watt pistol grip solder gun to repair printed circuits on dash panels. Get the gun running full hot, quickly apply the tip and the solder just long enough to tin the wires, and pull away. There's not enough time for a long section of wire to overheat. Lower-heat irons need to stay in contact with the connection longer, and a bigger area gets to critical heat. Be sure to uase rosin-core solder, not acid core.
Jerry

So I went to buy a fusible link today. The packaging clearly stated that the fusible link needs to be 2 gauges smaller than the gauge wire you are using it on. I'm using a 10ga wire from the battery post on the starter to the ammeter ( and that's the section I want to put the fusible link in right? ), so from what the packaging states, I should use 14ga. Not that I'm doubting what you are saying, but what gauge should I use: 10ga, 12ga or 14ga?

The "2 gauge smaller" rule of thumb is OK, so a 14 Ga. in the alternator charge lead will be just barely sufficient. Personally, I like a little more current capacity. The fuse link is a "last resort" fuse to prevent a wiring harness fire in case of a dead short. It's not some sort of hard and fast rule that will make all your children be born naked if you fudge a little. In today's litigious society, everybody who manufactures anything tries to make their products lawyer-proof and common sense gets tossed out the window. I think a 65-75 amp alternator trying to push its full capacity through a piece of 14 gauge wire occasionally is more likely to cause a problem than using a little common sense and still protecting against a dead short. Your mileage may vary!
Jerry

So 12ga to be on the safe side, 3" long?

Sounds good to me. It's highly unlikely it will ever be needed, but we also carry a spare tire, don't we?
Jerry