High output alternator
Thread Starter
Melting Slicks
Joined: May 2006
Posts: 2,364
Likes: 103
From: Centerville Louisiana
High output alternator
Looking for information on high output alternators. Electric fans and fuel pump running headlights could that be enough to tax a stock alternator? Any good sources for info would be appreciated.
Team Owner
Joined: Oct 1999
Posts: 34,034
Likes: 222
From: Land of Thunder
2018 C2 of Year Finalist
St. Jude Donor '12-'13-'14-'15, '19
Madelectrical.com
Takes a while to read, but is well worth every minute you spend on it.
And yes, your stock alternator will be huffing and puffing.
Takes a while to read, but is well worth every minute you spend on it.
And yes, your stock alternator will be huffing and puffing.
Le Mans Master
Joined: Dec 2006
Posts: 8,837
Likes: 1,028
Powermaster 8207. Switch the sheeves, get an adapter pig tail, and it bolts right in.
http://www.powermastermotorsports.com/catalog.html#
http://www.powermastermotorsports.com/catalog.html#
Racer
Joined: Oct 2017
Posts: 312
Likes: 64
From: Henry county ohio
I bought a 120 amp chrome 10si off eBay for under $100, delivered.
It was a direct bolt on. Came with a v-belt pulley, and it didn't require changes to the existing harness, although I did make up a new 6ga. power and ground harness to the starter.
I'm running dual electric fans, huge audio amplifiers, and halogen headlights. No problems after 5000 miles.
We will see how long it lasts. Worse case scenario, I have to rebuild it later, but it would still be chrome. Woohoo.
Good luck.
Jeff
It was a direct bolt on. Came with a v-belt pulley, and it didn't require changes to the existing harness, although I did make up a new 6ga. power and ground harness to the starter.
I'm running dual electric fans, huge audio amplifiers, and halogen headlights. No problems after 5000 miles.
We will see how long it lasts. Worse case scenario, I have to rebuild it later, but it would still be chrome. Woohoo.
Good luck.
Jeff
Race Director
Joined: Mar 2016
Posts: 14,302
Likes: 8,106
From: Napa Valley California
I’ll be running a Powermaster 17294, 100amp, 12 S, which can be run with 1 or 3 wire set ups and has a nice chrome finish.
I called Vintage Air and Dewitt's who told me that 100amp will be plenty to run the ac, dual Spal fans, headlights and not have any issues on the road or idle.
Both told me that if I was planning to run EFI, electric fuel pumps and an updated sound system to consider a higher amp alternator.
I called Vintage Air and Dewitt's who told me that 100amp will be plenty to run the ac, dual Spal fans, headlights and not have any issues on the road or idle.
Both told me that if I was planning to run EFI, electric fuel pumps and an updated sound system to consider a higher amp alternator.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
Race Director
Joined: Jun 2000
Posts: 10,037
Likes: 668
From: FL
Powermaster 47294-104 here. 150 amp 12SI. I am running a 340lph Aeromotive Pump, FAST XFI and MkVIII fan. Works great. Voltage stays at 14.3 to 14.5 volts at idle even with fans running and all lights on.Added a second charging cable direct to battery (so my AMP gauge barely moves anymore).
Team Owner
Joined: Oct 1999
Posts: 34,034
Likes: 222
From: Land of Thunder
2018 C2 of Year Finalist
St. Jude Donor '12-'13-'14-'15, '19
Powermaster 47294-104 here. 150 amp 12SI. I am running a 340lph Aeromotive Pump, FAST XFI and MkVIII fan. Works great. Voltage stays at 14.3 to 14.5 volts at idle even with fans running and all lights on.Added a second charging cable direct to battery (so my AMP gauge barely moves anymore).
Race Director
Joined: Jun 2000
Posts: 10,037
Likes: 668
From: FL
http://powermastermotorsports.com/fa...rnators_a.html
Will a higher amp alternator hurt my battery or charging system?
No. A good rule of thumb is that more amps are not harmful, but more voltage is. If you look at electrical power like water, amperage is equivalent to the volume of water, and voltage is equivalent to water pressure. More amperage is like having a larger pool of water to draw from.
Is there any modification I need to do to my wiring to install a high amp alternator?
Powermaster recommends increasing the size of the charge wire from the alternator to the battery. Recommendation regarding the proper wire gauge can be found here.
No. A good rule of thumb is that more amps are not harmful, but more voltage is. If you look at electrical power like water, amperage is equivalent to the volume of water, and voltage is equivalent to water pressure. More amperage is like having a larger pool of water to draw from.
Is there any modification I need to do to my wiring to install a high amp alternator?
Powermaster recommends increasing the size of the charge wire from the alternator to the battery. Recommendation regarding the proper wire gauge can be found here.
https://alternatorparts.com/do-i-nee...tery-wire.html
Do I Need a Bigger Battery Wire to the Alternator?
Battery Wire Size and High Output Alternators
When upgrading to a higher output alternator you should always install a larger wire between the alternator and battery . Even with a standard output alternator you will get better performance and life out of your alternator if you upgrade the main battery wiring. The original wire just isn't large enough for proper power transfer. If you are using your alternator to it's maximum output or when you upgrade to a higher output Alternator you must increase the wires size. An alternators ability to send the power it is making to the battery is directly related to the wire size and quality of connection between the alternator and battery. Also, a wire that is to small when used on a high output alternator can cause the power to back up within the alternator making it overheat, burn up and fail.
Another area that little is paid attention to is the ground. You must also improve the ground as well. A poor ground will hinder the alternators ability to send power to the battery and can burn an alternator up just as fast as an inadequate alternator to battery wire. Your ground may be fine when you first install your alternator but over time corrosion and resistance builds up in the ground connections. This is why it is best to run the ground directly from the rear of the alternator to the battery.
Here is another great auto electric tip from Alternatorman on upgrading the wire between the alternator and battery. Alternatorman says, you do not need to rip out your old wiring when upgrading. You can piggy back a second wire between the alternator and battery. The main battery wire connected to the back of the alternator has power to it at all times, even when the vehicle is shut off. You connect this wire like normal then you run a second wire between the alternator and battery. The power coming out of the alternator will treat the two wires as one, power follows the path of least resistance.
On a safety note, when running the second wire you should fuse it near the battery. The fuse is just in case the wire gets pinched or shorted out, the fuse will blow instead of the wire burning up. You should use the largest fuse you can for the wire size, fuses are restrictive to current flow. Typically you want the fuse value to equal 80% of the wires load carrying capacity.
Battery Wire Size and High Output Alternators
When upgrading to a higher output alternator you should always install a larger wire between the alternator and battery . Even with a standard output alternator you will get better performance and life out of your alternator if you upgrade the main battery wiring. The original wire just isn't large enough for proper power transfer. If you are using your alternator to it's maximum output or when you upgrade to a higher output Alternator you must increase the wires size. An alternators ability to send the power it is making to the battery is directly related to the wire size and quality of connection between the alternator and battery. Also, a wire that is to small when used on a high output alternator can cause the power to back up within the alternator making it overheat, burn up and fail.
Another area that little is paid attention to is the ground. You must also improve the ground as well. A poor ground will hinder the alternators ability to send power to the battery and can burn an alternator up just as fast as an inadequate alternator to battery wire. Your ground may be fine when you first install your alternator but over time corrosion and resistance builds up in the ground connections. This is why it is best to run the ground directly from the rear of the alternator to the battery.
Here is another great auto electric tip from Alternatorman on upgrading the wire between the alternator and battery. Alternatorman says, you do not need to rip out your old wiring when upgrading. You can piggy back a second wire between the alternator and battery. The main battery wire connected to the back of the alternator has power to it at all times, even when the vehicle is shut off. You connect this wire like normal then you run a second wire between the alternator and battery. The power coming out of the alternator will treat the two wires as one, power follows the path of least resistance.
On a safety note, when running the second wire you should fuse it near the battery. The fuse is just in case the wire gets pinched or shorted out, the fuse will blow instead of the wire burning up. You should use the largest fuse you can for the wire size, fuses are restrictive to current flow. Typically you want the fuse value to equal 80% of the wires load carrying capacity.
By doing this, I am avoiding pumping 100+ amps thru factory wiring designed for 40 amps, plus factory amp gauge no longer pegs under load.
Last edited by SteveG75; Jan 6, 2020 at 11:51 AM.
Le Mans Master
Joined: May 2003
Posts: 8,874
Likes: 3,551
From: Fernandina Beach FL
2023 Restomod of the Year finalist
2020 C3 of the Year Winner - Modified
Car batteries (marine are a different animal) are designed to give a bunch of current when starting and charge up equally as fast.
I run a 1/0 directly from the alternator to the battery and then EVERYTHING else off the battery. I have a lot of electrics- Electric power steering-Electric fuel pumps-12 Fuel injectors- 12 coils- electric AC compressor- Dual electric fans-upgraded headlights 80/100w- electric headlights-etc I also added a bunch more grounds...
This same wiring is done by BMW ($100K car new)- wired directly from the alternator to the battery- then everything off the battery.
***NOTE**** If piggy backing wires- running in parallel - make sure each is protected- current flows both ways!!! The fuse should protect the WIRE size.
