Big 3 Wiring upgrade questions and help

[stang233]

I would like to do the big three wiring upgrade on the boat. Power and groud wire upgrades...Full tilt with an amp meter stereo is running about 140 amps.

The big three is a good start. If I want to upgrade the alternator at any time. I was wondering if anybody knows how the power wire is ran? Does it go directly from the alternator to the batteries or does it go alternator, starter batteries I haven't spent much time digging into it and thought I would do some research here. The harness off the alternator appears to go to the ECU, but I doubt power is routed through the ECU from the alternator. 

 

2009, 23 LSV. 350 monsoon.

 

[hawaiianstyln]

Indeed swap out the alternator wire.  I had extra 0 AWG from my big stereo install and i just used that.  The Alt wire goes to the starter, then you should have a big wire that comes off the Alt that goes to dual batt switch (if you have one).  

[stang233]

Did you remove the original wire or just disconnect it and leave it? Do you recall how many feet of 0 gauge u needed? 

[shawndoggy]

0 awg from alternator to starter is probably overkill but won't hurt.  The factory wire on new boats from the starter to the batteries is 00 awg.  0 awg is undersized for the power and ground from batteries to starter/block.

[MLA]

2 hours ago, shawndoggy said:

0 awg from alternator to starter is probably overkill but won't hurt

Given the lenght of the typical supply cable from alternator to starter, 0 ga would support about a 600A alternator. About the diameter of a pony keg. 

[stang233]

Thanks folks.  For those of you that did rewire did you just leave the old 4 gauge or chose to remove it? Thanks again for your help 

[stang233]

Well good news I guess.  Tore into the boat and it already has 2/0 from the alternator to the perko switch.   Only 4 gauge from the alternator to the starter. Only 4 gauge from the switch to the batteries.  I know the run is short but I will still move the 4 gauge to 2/0.