Optima Yellow Install Pain

[Rich]

[quote author=shocker link=board=2;threadid=12675;start=msg117215#msg117215 date=1078762584]

The main battery cables will reach fine, but the two 8 gauge cables from the fusible link box outside the battery tray (inside yours now) need to be replaced with longer ones....

...I made two 12 inch long wires that reach into the battery much better.

...
[/quote]

Ryan, the two wires you replaced ARE the fusible links. They are not both the same gauge. Neither one is 8 gauge. The third fusible link you put in series with your replacement wire should not be connected in series with any other fusible link. If you look at the wiring harness behind the battery box you will see that if you untape and then retape the bundle you will be able to get all the slack you need to use the factory fusible links and maintain the intended fire protection.

Rich

 

[ryanjl]

[quote author=Rich link=board=2;threadid=12675;start=msg120674#msg120674 date=1079205520]
Ryan, the two wires you replaced ARE the fusible links. They are not both the same gauge. Neither one is 8 gauge. The third fusible link you put in series with your replacement wire should not be connected in series with any other fusible link. If you look at the wiring harness behind the battery box you will see that if you untape and then retape the bundle you will be able to get all the slack you need to use the factory fusible links and maintain the intended fire protection.

Rich
[/quote]

I used 8 gauge wire because it was the exact same O.D. as the OEM wires, which on my vehicle were the exact same diameter as one another. What gauge should they be?

If I continue to use my existing setup, I probably should extend the third wire (the "green" one I have running into the box in the photo above) and run it directly to the battery.

I see your point on the wires themselves being fusible links. I used the term "fusible link box" because that is what it is referred to as in the FSM.

In what circumstance would the fusible links be utilized as such? Short? Could a fuse be put in-line on each of the wires to replicate the set-up?

 

[Photoman]

Fusible links are just a smaller gauge wire usually used in higher amp circuits so they burn up first if there is a short instead of your whole system. They will probably go by the wayside now, with the higher amp Maxi fuses becoming more popular. One of the wires you are working with comes from the alternator IIRC, so you would need to install a Maxi fuse in this wire for somewhat more than your alternator output. Stock output on a 97 is 80 amps. I don't know what the draw is for the other wire so don't know what size fuse it should be. You could probably guesstamate it based on the fusible wire size Toyota used since the idea is to have the fuse blow before your wiring goes up in smoke.

Bill

 

[Rich]

At the moment I'm thousands of miles away from my land cruiser so this is all from memory. On my 97, there are 3 fusible links connected to the battery. One is marked 2.0, one is marked 1.25, and one is marked .3. The first two listed above connect to the little black terminal box. Those numbers are the circular cross section in square millimeters of the copper wire in the fusible links. The 2.0 is close to, but not exactly the same as AWG 14 gauge. The 1.25 is close to, but not exactly the same as AWG 16 gauge.

The fusible links are just short sections of copper wire that are smaller gauge than the harness they protect. The design intent is, in event of a short, the fusible link wire melts, and prevents the rest of the harness from catching on fire. Of importance is that the insulation on the fusible links is of a special formulation that will not catch on fire even when the copper wire inside gets hot enough to melt.

If you hunt around you can buy lengths of fusible link wire to make your own. Note that the longer the link, the greater the voltage drop that will be induced in the circuit. How much of an issue extra length would be I haven't calculated, depends on length of wire and the total amps drawn.

Anyway, if you look behind your battery box, you will see that the wire harness that the fusible links connect to is wrapped with tape going down to and along the inner fender well. If you unwrap the tape you can get all the slack that you need for the factory links to reach your battery post. I'd rewrap the harness after you have freed up enough slack.

Rich