Hello All,

I recently found I need to replace my alternator, and while I am there I would also like to upgrade the OEM run of wire from the Alternator to the battery in the trunk.

I've done some math on power loss over the oem wire at full load, and with a high output alternator there would be a meaningful difference from the perspective of my rather...involved...sound system. (With a higher amp alternator there is between 3%-5% power loss across the stock lead)

I have not been able to find out much information about doing this, which isn't surprising...There are not many SPL/SQL Mini Cooper setups out there.

So, I figured I would throw this out here and see what I can learn from anyone who has done any work involving the positive lead.

The main information I am looking for is:

1. Any details about how it is ran from trunk up, I assume it follows a passage under the exhaust shielding?

2. What kind of pass through does it go through, and where are they located? I can see the one from the battery space in the hatch, but I assume there are more. I need an idea of what gauge wire I can fit through.

3. Rough length/other routing information such are how it is terminated?

4. How is it split off from the lead to go to the alternator and the 12v stud used for jumping the car?

In an ideal world, I would like to run something absurd like Knuconcepts 4/0 gauge, just to future proof it. But I doubt that will fit.

Anyways, any information on practical concerts with replacing the positive lead would be great.

Thanks
Matt

 

Here is the wire itself if that helps.

There is a split year in 7/2004 models , for the hardtop.

: 61121508931 to 7/2004

https://www.ecstuning.com/Search/SiteSearch/61121508931/




: 61126942507 from 7/2004


https://www.ecstuning.com/Search/SiteSearch/1126942507/






" 4/0 gauge " thats huge, wow. Good luck. This above will give you an idea what it looks likes off the car and what it consist of.

 

Yeah, 4/0 is definitely overkill. But seeing as how it's such a long run, and it would be such a pain later to upgrade if I needed to, I figure I'll just buy a single run of the largest hi-flex wire I can find.

Assuming I can fit it. I may need to downsize based on how the wire is passed through the car.

By the looks of the picture the lead doesn't split off the the jumper-post by the air box...I wonder if that means it goes to that post, and then comes off the post and goes to the alternator.

 

Actually the battery cable doesn't run the the alternator. It runs from the battery on the driver side to the jump post under the hood. Then there is another cable smaller that runs to the alternator.

So if you unscrew the jump post you will see how the wire comes apart down to the alternator.

Be aware if you remove the factory cable you will get an airbag light since the cable explodes like an airbag in an accident.

 

So essentially the jump post acts as a distribution block?

That makes things a lot easier. I could upgrade my lead from the alternator to the jump post (which would be hard to do without the car in front end service mode) and then later, when/if I need to based on power requirements, I could upgrade the main lead. (I imagine I could put a resistor in place of the unit that disconnects the battery to avoid a light, and then fuse with an appropriate fuse to maintain most of the functionality of the exploding terminal.)

What sort of connection does the alternator use for the positive lead? Most alternators I have seen use a stud and ring terminal, but I've also seen some use a connector of some variation.

Thanks again everyone!