Alternator How Big is Big Enough
Thread Starter
Intermediate
Joined: Nov 2004
Posts: 46
Likes: 0
Alternator How Big is Big Enough
How big of an alternator does anyone run with dual electric fans plus a 1200 amp stereo? I've heard that the 140 amp alternators are not very reliable. Any input would be greatllly appreciated, Thanks!
Melting Slicks
Joined: Mar 2007
Posts: 2,100
Likes: 12
From: Frederick Maryland
I don't know what amperage alternator is sufficient for your needs, but I understand if you go much beyond a 100 amp unit you might need to upgrade the wiring harness to handle it. I've also been told you can run a heavy gauge wire directly to the battery to avoid that necessity.
Maybe someone else can give you more solid information than that. Sometimes one upgrade leads to another out of necessity, then that makes another upgrade unavoidable. Kind of like opening Pandora's Box.
Maybe someone else can give you more solid information than that. Sometimes one upgrade leads to another out of necessity, then that makes another upgrade unavoidable. Kind of like opening Pandora's Box.
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
For your setup a CS144 would be perfect. It's a stock reliable 160 amps at idle and 200 amps at higher RPMs. Change the pulley, buy an adapter if you don't have a GEN light, move or shorten the upper adjustment bracket, and you're all set.
If you are worried about the stock wiring, you can run a larger gauge power wire from the battery lug on the alternator to the starter lug.
PS - I think you meant 1200 watt stereo...but I seriously doubt it draws that much on anything but a split second at max volume.
If you are worried about the stock wiring, you can run a larger gauge power wire from the battery lug on the alternator to the starter lug.
PS - I think you meant 1200 watt stereo...but I seriously doubt it draws that much on anything but a split second at max volume.
Last edited by Durango_Boy; Oct 8, 2008 at 11:47 AM.
Safety Car
Joined: Mar 2007
Posts: 3,652
Likes: 49
From: Bridgewater nj
My stock 82 ALT is just enough to keep my dual fans spinning and if I'm stuck in traffic with AC & wipers on, the voltage drops to 10v. My stock alt. is around 70 Amps so my next Alt. will be 100 Amps. This shoud be more than enough to run all the electronics ECM, fuel injection, power everything, electric fuel pump, dual fans, ect... You see where I'm going with this
Your 79 doesn't have half the stuff that's crammed into an 82 Crossfire
Your 79 doesn't have half the stuff that's crammed into an 82 Crossfire
Le Mans Master
Joined: Aug 2003
Posts: 7,720
Likes: 12
From: Chattanooga TN
For your setup a CS144 would be perfect. It's a stock reliable 160 amps at idle and 200 amps at higher RPMs. Change the pulley, buy an adapter if you don't have a GEN light, move or shorten the upper adjustment bracket, and you're all set.
If you are worried about the stock wiring, you can run a larger gauge power wire from the battery lug on the alternator to the starter lug.
PS - I think you meant 1200 watt stereo...but I seriously doubt it draws that much on anything but a split second at max volume.
If you are worried about the stock wiring, you can run a larger gauge power wire from the battery lug on the alternator to the starter lug.
PS - I think you meant 1200 watt stereo...but I seriously doubt it draws that much on anything but a split second at max volume.
a 160amp CS144 should do fine. I would run another wire from the output to the starter lug. I have heard that you have to disconnect your ammeter if you have one, but no actual experience with that. I changed my car to a voltmeter already.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Check the power supply current requirement for your stereo...rather than the speaker "power" rating. It should be listed in terms of input amps. Add that to the max. fan current, add 20 amps for all lights (estimated), and another 30 for "good measure" [everything else]. Whatever that adds up to is what you need for a current rating on the alternator. [Note: Audio amps don't require the same input amps as needed for peak speaker output rating because the capacitors in the amp supply any excess for instantaneous peak needs. What you want is the continuous current input requirement.]
