I'm dealing with a 2007 ZO6. I just bought a new alternator, 250 Amp, 110 amps more than the stock one. The manufacturer says I need to change some of the battery cables and grounds. From what I can gather I need to change the one that goes from the battery to the lug on the fuse box under the hood. They say 2/0 but I'm thinking because it's so long it needs to be bigger? Then the other two cables that both go from that same lug on the fuse box, one to the starter and the other to the alternator. 2/0 may be fine for these and they are no more than 2" and 4" respectively. now the ground wire on the battery, the one I have no idea where it goes. I'm guessing that it should ground to the frame somewhere near where it exits the trunk and then there's another ground wire on the motor that also goes to the frame. So is there anyone here with better knowledge than I that get me straightened out on exactly what needs to be done here?

The manufacture of this alternator is trying to sell me a 48" 2/0 red cable and two 1/0 black ground cables, one is 36" the other is 32", without even asking me what type of car it is. Kind of concerns me. Sounds like it's for a base Corvette.

Any great ideas will be much appreciated.

 

What is the extra drawn on the OEM charging system, that you need a larger amperage output alternator in the first place.

The stock wiring has you covered up to about a 170amp 6 pole billet alternator. Hence 6 pull 170 billet alternator puts out about 45+ amps at idle, while the OEM valeo 140 amps alternator, puts out about 14 amps at idle isntead.

So really, if the problem is low voltage at idle, and not needing more amperage for say new stereo amps in the car that would be pulling 100amps on their own, then your wasting your time with the 250 amp alternator. Worst yet, could be just a 3 pole design like the stock units, while is only going to put out less than 20 amps at idle, and will not even begin to hit that 250 amps until the RPMs are above 3K.

Also, stock raditor pulls about 18 amps, while dual fan set up pulls about 40 amps isntead. Hence still covered for power needs with the 170amp billet 6 pole billet alternator, since it puts out more amps at idle, that it's the larger billet amperage alternator.

As for if you are going to run a 250 amp unit, then need to run a larger gauge wire from the alternator to the engine fuse box terminal (with fuse in line). Hence stock cable from the alternator to the starter solenoid has a slow burn fuse link in it (wire 2 gauges smaller for a short section) and if you try to push 250 amps through it alone, its going to melt the slow blow fuse link. So the extra wire cable, allows more power to get to the engine fuse box terminal, and the point that you would be wiring all the after market power item to the car in the first place.

Bottom line, tell us what you are powering after market, where you are having problem with the charging system now, and we can advice on the best plan of attack. As for just slapping in a 250 alternator for no good reason, that a lot of extra drag on the belt, hence losing HP due to such.

 

I live in Houston so my next move is to get a new twin fan set up. Also going to upgrade the worthless Bose sound system. The radio in my 2006 E150 cargo van sounds better, seriously. also seems like the OEM alternator can barely keep up with the electrical needs it has now. In warmer weather around idle the voltage won't maintain itself in the 13.2 range and above unless I get it going faster. I'm not averse to getting the new wires but I don't know enough about it to get it right.

Thanks a lot for your comments. I really appreciate it.

 

Short of dropping in two or more stereo amps that are pulling 50 amps each (uses 50 amp fuses each), OEM power, plus dual fan set up, and say 40 amp total on the radio ampifiers, Mechman billet 6 pole 170amp alternator has you covered for oem, plus added power and will cover you on the low voltage problem at idle for the most part.

The only thing I would add in, would be an another wire from the alternator to the engine fuse box terminal of about 4 gauge with in line fuse, to cover the added power that the stereo amps and dual fans are pulling from the fuse box termial, so not all the power is being pulled through the oem alternator to fuse box terminal alone (with slow blow fuse).

Hence run is about 6 feet, and 4 gauge wire can carry 95 amps/will be all that is needed to supplement the oem cable to the battery with the 170 amp alternator.

As for 2/O wire, it rated at 175 amps,and if you run that, you can pretty much cut out the OEM alternator to starter cables, since it will be covering the entire amperage load of the alternator itself. As for ground side, just battery to engine block/rail, to upgrade the OEM ground cables as well.

 

Agree with the above. Think about a typical home electrical panel - usually 200 amps. Nothing in the house comes close to needing 200 amps. It's just max capacity. If you aren't adding something that will use the additional capacity, problem solved - no wiring changes required.

 

I'd still like to know how far the negative cable goes from the battery. I also can't see any cable that goes from the block to the frame.

 

It's should be in the area of the ECM/ABS controllers. On the L99 (that's the closest thing I have to compare with at the moment), that cable is on the block at the radiator/heater hoses location. It's a black cable the size of your little finger.

The frame is the ground from the battery to the engine compartment, at least on the L99 (the Camaro SS equivalent of LS3).

Nick

 

Your battery ground cable goes this far,
Note, VCT tiles are "12X12", so about 3' up from the battery in the back, before the other end bolts to the chassis rail to ground out there.