upgrading alternator wiring

Kejtar

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so..... lets look at a scenario of a 160amp alternator and about 8 or 10 gauge wire from alternator to battery. If I go with the 8 gauge theory (I'm eyeballing it) that means that I really get at most 73 amps through it (give or take - depending which chart you use).

There are couple options now ahead of me - either replace the whole wire (PITA) or add another in parallel (more appealing). Now lets assume that the stock wire has a fusible link buried someplace in there....

So if I go the simpler route and if I run a 2 gauge in parallel the question is should I put a fusible link or a circuit breaker on it?
 

trippled

NAXJA Member
NAXJA Member
Why not just remove the factory wire and run a large cable? I ran mine to a audio ANL fuse holder then to the battery. Simple and works fine.
 

Kejtar

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Ok so let's say that I do pull the stock wire... again question stands - fusible link or a circuit breaker?
 

Kejtar

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Size of the fuse is debatable as with a 6 foot run of 4awg 120 amps is probably where I will be happy. Also I do not expect the draw to ever come close to the max.... Hell.... Currently I am at the fraction of that due to factory wire size limitation...
Anyways the question is... Can I use that circuit breaker and what is the pro/con of it over the fuse/fusible link
 

Jeep Driver

New member
Size of the fuse is debatable as with a 6 foot run of 4awg 120 amps is probably where I will be happy. Also I do not expect the draw to ever come close to the max.... Hell.... Currently I am at the fraction of that due to factory wire size limitation...
Anyways the question is... Can I use that circuit breaker and what is the pro/con of it over the fuse/fusible link
This has nothing to do with draw, has to do with output.

If you have a 160amp alt, it WILL put out 160 amps.

You are protecting the entire electrical system from the alt........again, nothing to do with draw.


Best you will have is 18" of 4g wire from the alt to the battery/starter relay/PDC.


No, I would not use, did not use, a breaker.
 

Jeep Driver

New member




This is what a properly wired high output alt will look like.



If you use a 150amp breaker with a 160amp alt, you will be constantly resetting the breaker..........you need to be beyond 160amp. IIRC, 200amp breakers, good ones, get expensive.
 

Heavyopp

NAXJA Member
NAXJA Member
I have a spare 100 ft roll of 1/0 welding cable -- think I'm gonna use that to rewire my 160 amp alternator -- also thinking about doing the line to the starter -- and an aux line to the rear for "house" power

How reliable are those mega fuses? Ever blow one?
 

Jeep Driver

New member
I have a spare 100 ft roll of 1/0 welding cable -- think I'm gonna use that to rewire my 160 amp alternator -- also thinking about doing the line to the starter -- and an aux line to the rear for "house" power

How reliable are those mega fuses? Ever blow one?
Megafuse is standard on Ford trucks.

 

Anak

Stranger
NAXJA Member
If you have an HO PDC you can add a fuse at the end of it.

Components, the way I did it:





Assembled:






Somewhere around here is a picture of everything in place, but I can't seem to find it at the moment.

I would ditch the fusible link. Those things just bug me. It is far easier to test a fuse for continuity and far easier to replace it should the need arise.

ETA: Check out this thread for ideas: http://www.naxja.org/forum/showthread.php?t=1114880
 
Last edited:

donthelegend

NAXJA Member
NAXJA Member
This has nothing to do with draw, has to do with output.

If you have a 160amp alt, it WILL put out 160 amps.

You are protecting the entire electrical system from the alt........again, nothing to do with draw.

No, I would not use, did not use, a breaker.
You need to be beyond your amp output...............175 at least, if not 200.
If you use a 150amp breaker with a 160amp alt, you will be constantly resetting the breaker
This is pretty much all incorrect.

1.Alternators aren't constantly putting out max current. They aren't putting out any more current than is being drawn by the system they're attached to. It has EVERYTHING to do with draw.

2. A 160 Amp alternator will only put out 160 amps under certain conditions, namely, when turning fast enough to produce that much current, and when there is that much current being drawn by the battery, engine, lights, radio, and whatever else is using power in the system.

3. Because of 2, if you don't ever need more than 150 amps, there's nothing wrong with 150 amp breaker/fuse on a 160 amp alt. The breaker/fuse is there to protect your wiring first.

4. Nothing wrong with the breakers instead of fuses, I run a 125 amp breaker in my daily driver XJ with stock alt. I run a 150 amp ANL fuse in my trail rig with a 160 amp alternator. Have never popped the breaker or fuse. Installed 125 amp breaker in two other XJs with stock alternator output without problems. All with 4 gauge cables I made.


To the OP:
Get rid of the fusible link/stock alternator positive wire entirely. Replace with 4 gauge or larger wire, with either a fuse or breaker sized to protect the wire or to match the output of the alternator, whichever is smaller. (IE: 0 gauge wire will handle more power than a 136 amp alternator will ever produce, so i'd suggest a 150 amp fuse/breaker which is probably the closest to 136 you'll get without being under sized). Alternatively, if you don't ever need the extra power, you'd probably be fine with a 125 amp breaker, but there's no real reason to undersize the breaker since the wire will handle the extra current without a problem.
 

RCP Phx

New member
^^^^^^This is correct, I don't know of a better way to explain it! Jeep Driver lives in a world of his own!
 

Kejtar

PostMaster General
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NAXJA Member
thanks guys! I was starting to doubt myself but what helped me hold onto my sanity is the fact that the stock skinny wire is not burning up and it definitely does not handle 160 amps....

I'll look into getting rid of the stock wire, but I want to make sure that there is not a connection going someplace in the loom between the alternator and the battery that I'm overlooking. That's the main problem - loom is buried - and ..... gasp..... it's not an XJ that we're talking about :) And I don't have an FSM for this rig...
 
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