1st Time Jeep Owner

[Catlewis]

Wiring Diagram supplied with the harness.

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[Catlewis]

The alternator I'm installing is substantially high amp than original. New one is 105 amp! Will this also require changing the coil. Pretty sure the coil is original 1965 era.Capture alt.jpg

[gmwillys]

The new alternator is internally regulated, so no matter how many amps the alternator is rated at, (peak output of 105) the alternator only puts out what the battery needs to stay charged. Your coil still will only see 12 volts, so you'll be OK as long as the coil is in good shape. Senior Chief can correct me if I'm not thinking this all the way through.

[bmorgil]

gm is correct. I think your only concern is the charge line.The big wire from the Alt to the battery positive. As LarrBeard pointed out, at least 6 gauge there. Use pure copper wire only. If the battery is dead and you get the RPM's up high enough, the charge line will put 100 amps to the battery to charge it.

[Catlewis]

Thanks for the info (everyone). Really think it needs 6ga? Most everything I read suggested 10ga. I bought a small spool of 10ga. already however want to do the right size.

[bmorgil]

That is a great question that requires some explanation. I am sure LarrBeard is out there somewhere and he can elaborate. By the math, it is a question of how much current draw in amp's (105 amps), how long of a run it is for voltage drop, and 2 very important questions. What is the duty cycle and what is the allowable temperature rise of the wire vs. time.

Take this data to the wire size AWG chart below or get another online. The allowable temperature rise is related directly to the duty cycle, and its a short one. We are talking about how hot the wire gets before it melts. The chart shows you how hot it will be at the size selected. This is called the "ampacity" of the wire. I am way over my head here and we need Larry to pipe in. Suffice it to say if you are going to pull 105 amps for continuous duty you need 4 awg. As you reduce that duty cycle, the wire size can be reduced. Here is the big question, will you ever pull all 105 amps? Now we really need Larry! The battery would have to be darn near shorted. It could happen. Since it is such a short run, on mine I have a (105 amp alt.) I use 6 awg. That is just in case I get near that 105 amp draw for any length of time. Any less than that and it could start to melt which creates more current draw as the wire heats up creating.... yikes.

So would 10 awg work... your answer is probably. Don't use anything but pure copper. Aluminum and copper coated aluminum are not good in an automotive environment.

https://www.awc-inc.com/wire-size-selection-guide/

[Catlewis]

Guess I'll be pickin up a piece of 6ga. wire. Also ordered the conversion alternator bracket set from Classic Military Vehicles.

[LarrBeard]

I came in a bit late, but I agree that #6, copper is the best choice.

The alternator will, as the other guys said, only deliver as much current as the battery asks for. Unless you put a honkin' big stereo or an awesome light display on the Jeep, there really is no way - other than a catastrophic short - that you would ever demand 105 amps.

Don't trim off strands to get the wire to fit on a connector and get the best crimp on the cable as you can. Terminals for #6 are pretty sturdy, so you might need to find a shop with a hydraulic crimper to get a good connection. If you can't crimp, a solder connection is a better choice that pounding the terminal barrel closed with a greasy ball-peen hammer (like Bubba and Junior do).

[gmwillys]

The greasy ball peen hammer works pretty good in a pinch. I finally invested in an Amazon special hydraulic crimper that works pretty darned good. The link is one kind of like the one I bought, but the cheaper version.

https://www.amazon.com/Hydraulic-Cri...minal-Crimping

[Catlewis]

I'm thinking pre-made cable for a garden tractor! Tractor Supply or somewhere similar.
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