Alternator went out

[Hollowdweller]

Looks like I’m gonna have to replace the alternator on my 2006 Roush….which one should I get? Prob need the 200amp….adding stereo system.

 

[Hollowdweller]

I jumped on an open box SR Performance 200amp from AM for $160…anyone ran one of those?

 

[Blue03Cobra]

I have one in a box, ready to go on. Make sure you upgrade the alternator-to-battery wire, for a 200A. Engine bay fires are no joke. This is the one I went with:

SR Performance Mustang Premium Power Wire Kit SR9909 (94-14 Mustang, Excluding GT500) - Free Shipping

FREE SHIPPING! Manage More Power. The factory OEM alternator power wire was not designed to carry the larger loads that high AMP replacement alternators produce

www.americanmuscle.com

 

[Hollowdweller]

I have one in a box, ready to go on. Make sure you upgrade the alternator-to-battery wire, for a 200A. Engine bay fires are no joke. This is the one I went with:

SR Performance Mustang Premium Power Wire Kit SR9909 (94-14 Mustang, Excluding GT500) - Free Shipping

FREE SHIPPING! Manage More Power. The factory OEM alternator power wire was not designed to carry the larger loads that high AMP replacement alternators produce

www.americanmuscle.com

Yeah I’ve been looking at that. I’ve already ran a 4awg from the alt to the batt when I had the motor out but noticed that ones fused. I didn’t fuse the one I did bcz it wasn’t fused from the factory. I don’t really understand the fuse location with that kit, I’d think it’d be closer to the Alt than the battery…? Still been thinking about it, used some power wire from my sound system install, dunno if it’s a different type of wire..?

 

[Hollowdweller]

Guess the alternator wasn’t the problem…crap!!!

 

[Blue03Cobra]

Are you sure? What caused the wiring issue?

 

[Hollowdweller]

I used a 4awg wire designed to power amplifiers. I’m assuming those little strands of copper couldn’t handle it. Maybe it was the heat and that type of wire. I reinstalled the factory wire with the stock alternator and am now getting 13v at idle. Figure I’ll order the wire upgrade kit from American Muscle and throw the new alternator in in a couple of weeks

 

[DieHarder]

Buy a new set of OEM battery cables. The fact that you're only seeing 13vdc at idle tells you they need to be replaced. You can still get them on feebay and perhaps some dealers but they're becoming scarce these days.

Pardon Our Interruption...

 

[Midlife Crises]

I didn’t fuse the one I did bcz it wasn’t fused from the factory

I believe the factory alternator wire has a fusible link but I don’t know the rating. Also #4 cable is not rated for 200 amps.

 

[JC SSP]

I use a custom 200AMP High Output Alternator with 4-gauge power wire with in-line 250AMP fuse.

 

[DieHarder]

I use a custom 200AMP High Output Alternator with 4-gauge power wire with in-line 250AMP fuse.

View attachment 108368

What's your running voltage across the battery terminals at idle?

 

[JC SSP]

14.1V at Idle and 13.9V at load (A/C, flashers, headlights on, etc.).

 

[DieHarder]

On the lower end of acceptable. Should be 14.5 vdc or better. You can try adding a ground cable from a mounting bolt for the alternator to the passenger strut ground. That will ensure ground is the same throughout the system. Due to age/corrosion it's likely that your battery cables/harness need replacing.

You can still get them on feebay:

Pardon Our Interruption...

 

[Dino Dino Bambino]

On the lower end of acceptable. Should be 14.5 vdc or better.[/URL]

The ambient temperature plays a part. In colder weather, the voltage will be higher because although the current stays the same, the resistance increases. The converse applies on hot summer days.
Therefore:

14.1V at Idle and 13.9V at load (A/C, flashers, headlights on, etc.).

Is fine at this time of the year.
That said, measure the voltage between the alternator casing and the passenger side strut tower grounding point. If you get a measurable reading, add a grounding cable between the two.

 

[JC SSP]

I am in Miami, FL always hot & humid. LOL

FYI My Audi is 13.8-14.2 and its relatively new. Wifes' 23' 5.7 R/T Durango is always 14.2-14.5 regardless, if at idle or under load, but that thing has a tone of electronics...

I will be keeping my eye on it and even considering buy a new battery harness, but other projects are ahead of this one.

 

[Shane361]

When using wire use OFC as it is the best. There is some very cheap wire out there. Generally if it flexes easy it is better than wire that is more stiff. Also no need to remove stock wire, just add to it. Also make it easier when going back to stock if needed.

 

[Pentalab]

I believe the factory alternator wire has a fusible link but I don’t know the rating. Also #4 cable is not rated for 200 amps.

# 4 ga wire is no way, shape or form, rated for 200 amps.... not even if it had 225 Deg C insulation.

My 2010 GT auto is 14.75 vdc across the battery terminals with eng on, in idle. It doesn't drop at all with halogen lights on, foglamps, oem stereo, etc.

 

[Laga]

On the lower end of acceptable. Should be 14.5 vdc or better. You can try adding a ground cable from a mounting bolt for the alternator to the passenger strut ground. That will ensure ground is the same throughout the system. Due to age/corrosion it's likely that your battery cables/harness needs replacing.

You can still get them on feebay:

Pardon Our Interruption...

Why not from alternator bolt to battery post?

 

[DieHarder]

# 4 ga wire is no way, shape or form, rated for 200 amps.... not even if it had 225 Deg C insulation.

My 2010 GT auto is 14.75 vdc across the battery terminals with eng on, in idle. It doesn't drop at all with halogen lights on, foglamps, oem stereo, etc.

This is ideal. The majority of our cars however are going on 15 - 20 yrs now and in many of them the inherent resistance has increased in the battery and ground cables due to corrosion & sulfates (that green patina). You often see this in the SJB as well due to water intrusion. Higher resistance in the cables/connectors (usually manifests as heat) creates a higher voltage drop across those elements meaning there's less voltage available for other circuit elements which we often measure as lower overall circuit output voltage across the entire system (positive to negative side of the battery).

 

[DieHarder]

Why not from alternator bolt to battery post?

You certainly could but the system ground is the frame and it's usually easier to run an extra ground from one of the alternator mounting bolts (i.e. same as case ground for the alternator) to the passenger strut tower ground (shown below) which is the same point that the negative lead of the battery is connected to.