[Nocturnal Thunder]

Hi folks, how's it going?

So I'm having an issue with the big 3 on my car. I have a 60ah lithium battery and an Autotech 320A HO alternator so obviously better wire is next. I'm planning on running 2/0 OFC welding wire and it looks like it won't be a problem except the firewall. I have a post through on the firewall that connects both sides. Here are some pictures so you can see what I'm talking about:

When I removed the stuff, this is what I found:

Now as far as the wire from the alternator to the firewall, it is not just one wire, its a bunch. It looks like this:

So here is my question: Am I going to need to drill a new hole in the firewall, put in a rubber grommet, and run the cable from the alt to the battery? I thought about adding a wire to the alternator and having it attach to the post through but since it would be touching metal, I think that would be really bad.

So what do you think, do I need to drill a new hole or is there something I can do that doesn't require that?

 

[Nocturnal Thunder]

https://www.summitracing.com/parts/mor-74144

View attachment 372836

https://www.summitracing.com/parts/mor-74144

View attachment 372836

Oh ****...that rules!!! That is even better than the grommet...I can connect a 4/0 welding wire to that. I think we have a winner!!! Thank you so much ckirocz28!!! By the way, what does your name mean?? I've never seen the word ckirocz before.

 

[Nocturnal Thunder]

Just to note, a 3/8" brass stud is good for 400A while a steel 3/8" stud is only good for 250A...

Yeah, I just read that they are only good for 100A which is not enough since I have a 320A HO alternator. However, I found one on Amazon rated at 440A continuous with peaks at 550A, so I'll probably go with that since my alternator is High Output. I can also go from 2/0 welding wire to 4/0 welding wire. I could even do the big 4 and drill two holes...one from alternator to battery positive and one from the alternator frame to the battery negative. This is a game changer for me.

High current through panel battery connectors

I ****ing love this place...thank God for DIYMA!!!

 

[Nocturnal Thunder]

As @Slave2myXJ pointed out above; you will be much better off with the only connections in the wire at either end. The 2/0 wire is plenty for any reasonable distance and you still need proper tools to make those connections on each end. The tools for 4/0 are starting to get into the size where you have to purchase separate dies for each wire size and use hydraulic crimpers (unless you intend to solder the ends on and that's a whole 'other' ball of wax)... additionally, that through post uses stainless nuts on an unknown metal plated copper post so if your wire end is brass then you've got copper to brass to stainless to mystery metal to copper and back again in dissimilar metals to cause dielectric changes, corrosion, resistance and noise.

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Luckily I have a 16 ton hydraulic crimper so that won't be a problem. Well, back to the grommet...I can forget about the big 4. Running one run of 2/0 or 4/0 wire will be difficult but two runs is going to be a pain in the ass. Thanks for the advice.

 

[Nocturnal Thunder]

The rule of thumb (unless your cable mfr says otherwise) is 2/0 is good for 400 Amps up to 50 feet.

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That is why I was originally planning on using 2/0 welding wire. With my subwoofer amp, I'm going to use 2/0 instead of 1/0 because of the amount of current I'll be pulling. The wire that connects my battery negative to the chassis is still going to be 4/0...you can't overdo grounds.