• Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech

bigger alternator 100 amp

  • Thread starter Thread starter noslow1986
  • Start date Start date Aug 28, 2007
N

noslow1986

New Member
Mar 25, 2006
274
0
0
oswego Il
Aug 28, 2007
#1
  • Aug 28, 2007
  • #1
is a 100 amp to much. not running speakers amps noting just underdrive pulley. just seems its not getting enough power. it does have a b cam. when i start it, its rough but the lights go dim and have to keep it running with foot on gas once its warm up its ok but idle drops downs a little and lights dim.. only computer codes are air diverter. no emissions but still running egr valve.
 

daddystang

New Member
Aug 13, 2006
185
0
0
Aug 28, 2007
#2
  • Aug 28, 2007
  • #2
I don't think it's too much. I'm running the PA Performance 200amp with no problems so far.

Hope that helps.

Joe
 
D

Daggar

New Member
Jul 19, 2004
3,902
5
0
Aug 28, 2007
#3
  • Aug 28, 2007
  • #3
There's really no such thing as "too much" in terms of the how many amps an alt is capable of putting out.

It doesn't mean that there will be 100 amps coursing through your electrical system any time it's turning. It will only put out UP TO 100 amps depending on the demand you have on your electrical system.

If you do plan on putting a demand on your electrical system that is over and above stock then you will need to upgrade your wiring. The stock power wires are not capable of sustaining a 100 amp (or even 80 amp) continuous draw for any length of time.
 

HISSIN50

"How long does it take to get help in here?
15 Year Member
Nov 29, 1999
31,179
33
129
Aug 28, 2007
#4
  • Aug 28, 2007
  • #4
Andy summed it up nicely.

Also, nearly any alt will suck at super low RPM's. It sounds like that's your issue. If your idle is low, you could try bumping it up to 800-900 RPM (or whereever the voltage goes up when you hold the gas pedal down).

Good luck.
 

ninety15.0

New Member
Mar 10, 2004
1,336
0
0
Aug 28, 2007
#5
  • Aug 28, 2007
  • #5
I second what Hissin said. When my car idles at 750 my 130amp alternator still has a hard time charging the battery. The lights wont really dim unless i have the heat on high or putting the windows Up/Down. When i pick the idle up to 900 it doesnt draw nearly as bad. Check out some of the 3G alternator conversions using the search function. Its a really easy swap that should only take you a couple hours...and it really pays off! I got my 130 amp from the junkyard...the thing looks brand new and came with a lifetime warranty...all for $50. good luck
 

TRWXXA

Member
Jan 18, 2003
190
1
19
RIGHT BEHIND YOU!!!... Made you look.
Aug 28, 2007
#6
  • Aug 28, 2007
  • #6
Upgrade your alternator, or put an overdrive pulley on it. If your headlights are dimming, you need more amps.

A 100 amp alternator will only be capable of putting out 40 or 50 amps at idle. If you are underdriving it, it might only be capable of 30 amps. Your headlights and HVAC fan can draw more than that.
 
You must log in or register to reply here.

Similar threads

J
Emission problems
  • jls.zmmr
  • Feb 5, 2026
  • 1994 - 1995 Specific Tech
Replies
2
Views
228
1994 - 1995 Specific Tech Feb 7, 2026
AeroCoupe
8
Engine Rough idle and aggressive sputtering when accelerating
  • 88vertible
  • Aug 13, 2025
  • Fox 5.0 Mustang Tech
Replies
4
Views
1K
Fox 5.0 Mustang Tech Dec 13, 2025
Jarhead67
J
M
Engine Unexplainable Exhaust Pop and Gurgle
  • Mrnissen122
  • Feb 14, 2026
  • Fox 5.0 Mustang Tech
Replies
12
Views
526
Fox 5.0 Mustang Tech Feb 18, 2026
Noobz347
Engine 1990 LX 5.0L EFI Mustang Fuel Management Problems - HELP!
  • 5.0LXStanger
  • May 25, 2025
  • Fox 5.0 Mustang Tech
  • 2 3
Replies
45
Views
2K
Fox 5.0 Mustang Tech Jul 11, 2025
5.0LXStanger
T
Help with a 95 5L crank no start
  • TheBubbaJoe
  • Nov 4, 2025
  • 1994 - 1995 Specific Tech
Replies
3
Views
429
1994 - 1995 Specific Tech Nov 5, 2025
AeroCoupe
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech
Menu
Log in

Register

  • Forums
  • What's new
  • Media
  • Resources
  • Contact
  • Sponsor
X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?

X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?