Fusible Link fix with added fuse box - FJ60 (charging)

Joined
Nov 5, 2021
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22
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Austin, TX
I had some wiring issues around the alternator and decided to just rewire all around the charging circuit.
Found some parts around town to make a crude but effective fix. This could be a great fix for someone stranded with a bad fusible link (diagram below with pictures)

I wanted to get rid of the fusible link because I was seeing voltage drop.

Fuse box was found at Walmart
All else I either had on hand or was bought at Oreillys including the 40 amp fuses.
14 gauge fusible link wire found at Oreillys.
I also replaced my ground from my battery : 10” 4 gauge wire to body (next to battery) mated to what is I believe a 32” 4 gauge to ac compressor bolt.

The 40 amp fuses are essentially replacing 2 parts of the fusible link. The third part of the link is the protection from the 14 gauge fusible link wire. This protects the alternator portion. You don’t want the alternator on a fuse. The rest has been perfectly fine on those 40 amp fuses. No issues or blown fuses. And the 40 amp rating is very close to what the factory design of the fusible links feeding those circuits are. I have had excellent charge with minimal voltage drop. My voltage meter I installed reads 14.2 V at 1000rpms. Needs some heat shrink and organizing but this is my daily driver and I needed a quick fix. If you have a short around the battery or alternator this could be a good upgrade.

There are some ways to improve on this design. Feel free to suggest.



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Joined
Aug 16, 2021
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33
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Bentonville, Arkansas, USA
That is a cool idea. I thought about doing something similar but wasn't sure about a blade fuse replacing a fusible link. I built some new fusible links using solder seal butt connectors. I'm going to make a backup set and keep a little kit in the cruiser. I'll just use crimp butt connectors in the kit. I used 20 gauge for the smaller two links and PICO 16 gauge (1mm ^2) for the larger. The grey and black wires in the pic below are the fusible links.

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Joined
Jan 4, 2011
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Vermont
I'd run a big cable directly from the alternator to the battery...marine 4 gage should work nicely. USe your fuse setup to isolate the main harness from the battery but optimize your alternator to battery connection as much as possible.
That is a cool idea. I thought about doing something similar but wasn't sure about a blade fuse replacing a fusible link. I built some new fusible links using solder seal butt connectors. I'm going to make a backup set and keep a little kit in the cruiser. I'll just use crimp butt connectors in the kit. I used 20 gauge for the smaller two links and PICO 16 gauge (1mm ^2) for the larger. The grey and black wires in the pic below are the fusible links.

View attachment 3119377View attachment 3119378
 
Joined
Aug 16, 2021
Messages
33
Location
Bentonville, Arkansas, USA
I'd run a big cable directly from the alternator to the battery...marine 4 gage should work nicely. USe your fuse setup to isolate the main harness from the battery but optimize your alternator to battery connection as much as possible.
Well the orignal setup was an 8 gauge wire, then the 0.85 mm^2 fusible link, then an 8 gauge to a three way crimp, then the 8 gauge goes on to the 55 amp alternator. I am a newb at this but from what I've read a 55 amp alternator can handle a couple of feet of 10 gauge and which is good for at least 100 amps. I'm wondering in the image below if this is the factory setup and what the unknown wire was for?

fj 60 alternator three way splice.png
 
Joined
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Messages
22
Location
Austin, TX
I'd run a big cable directly from the alternator to the battery...marine 4 gage should work nicely. USe your fuse setup to isolate the main harness from the battery but optimize your alternator to battery connection as much as
Started to do this last night. Thought to myself, “check the voltage drop from alternator to battery before you go do all that.” It’s neglible. Like 0.05V. Not worth my time. Because essentially you are trying to fight resistance with higher gauge. So for me a fresh 10 gauge wire is fine. If I was running more accessories with a high output alternator I would do it. 10 gauge just looks cleaner under the hood and is much easier to connect to the alternator post and work around. But yeah I agree. Off principle alone it’s a good suggestion. I just have other projects to spend my time on right now.
 
Joined
Nov 5, 2021
Messages
22
Location
Austin, TX
Well the orignal setup was an 8 gauge wire, then the 0.85 mm^2 fusible link, then an 8 gauge to a three way crimp, then the 8 gauge goes on to the 55 amp alternator. I am a newb at this but from what I've read a 55 amp alternator can handle a couple of feet of 10 gauge and which is good for at least 100 amps. I'm wondering in the image below if this is the factory setup and what the unknown wire was for?

View attachment 3119492
You should have 2 wires that come out of the fusible link and into your vehicles wiring harness, one thicker wire from alternator into the harness, and two smaller wires from alternator into harness for the charge light Indicator circuit. The third part of the fusible link connects your battery to the alternator. Anything extra would be accessories installed after factory wiring.
 
Joined
Jan 4, 2011
Messages
5,338
Location
Vermont
Started to do this last night. Thought to myself, “check the voltage drop from alternator to battery before you go do all that.” It’s neglible. Like 0.05V. Not worth my time. Because essentially you are trying to fight resistance with higher gauge. So for me a fresh 10 gauge wire is fine. If I was running more accessories with a high output alternator I would do it. 10 gauge just looks cleaner under the hood and is much easier to connect to the alternator post and work around. But yeah I agree. Off principle alone it’s a good suggestion. I just have other projects to spend my time on right now.
I have a lot of heavy gage wire around so it was easy to make up a nice heavy wire. It’s overkill but less heat and resistance when pushing the full load. It’s pretty amazing how a new set of heavy cables for the battery, starter, alternator, and main grounds can improve all the electrics in the vehicle.
 
Joined
Nov 5, 2021
Messages
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Location
Austin, TX
I have a lot of heavy gage wire around so it was easy to make up a nice heavy wire. It’s overkill but less heat and resistance when pushing the full load. It’s pretty amazing how a new set of heavy cables for the battery, starter, alternator, and main grounds can improve all the electrics in the vehicle.
I hear you. Use what you have and you can never go wrong with the thicker wire choice in these old things.
 

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