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Alternator charge characteristics

vetteboy86

Well-known member
Joined
May 26, 2003
Messages
2,760
Location
IN
Corvette
1986 Black "Indy 500 Pace car replica"
What is the common voltage output range for any run of the mill alternator? I have heard that from 13.5 all the way to 15 volts is acceptable. At what point is there a problem either on the low side or high side?

Thanks,
Craig
 
After start up, I usually see mid-14's for voltage. After 20+ minutes driving, the voltage usuallin drops to the high 13's - 13.7ish. If I'm seeing 15, I'm going to be concerned some. If I'm seeking less than 12.5, ditto. That's just my parameters for my cars and my piece of mind.
 
Acceptable range: 13.8 to 14.4 volts

What the problem is: accuracy of meters and/or gauges.

Save The Wave! :w
 
Ambient temperature and engine temperature has a direct bearing on alternator charging voltage.

Hot temperatures cause lower voltage readings.

Cold temperatures cause higher voltage readings.

Save The Wave! :w
 
Just converted my 86 alternator to the 140 amp. Now it idles at 14.1 v. with lights on and fans running.:D
 
How did you do this was it a direct bolt in? I looked at a 140amp from a 96 vette & its to plug right up but was unsure about the phisical fit.

Terry Colyer
RWDsmoke said:
Just converted my 86 alternator to the 140 amp. Now it idles at 14.1 v. with lights on and fans running.:D
 
The 140 amp is much larger, but the pulleys are the same so the belt still fits. The top bracket or the top alternator ear will have to be filed down a little to fit. Rear brace will have to be modified if you want to keep it. I'm not using the rear brace right now but I plan to install it later Wires plug in the same. Easy conversion.
 
tcolyer said:
How did you do this was it a direct bolt in? I looked at a 140amp from a 96 vette & its to plug right up but was unsure about the phisical fit.

Terry Colyer

Yep, direct bolt in. Picked up the Chrome Powermaster 140 amp from Summit.

:w
 
I would imagine that 17.25 volts would be cause for concern.
 
If you are meaning 37 volt ac! YES! You don't want Alternating Current!! Hard on Electronics!! (Bad Diode's) can let AC voltage slip past, Duz your battery Boil?? Duz your Radio buzz with eng. RPM?? 17.25 DC seams a little high I have seen my Car hauler Spike 16.2 when I use the top wench!! But it has 4 battery's and a 180 amp alt. from a Fuzz-mobile!!:upthumbs junk!!
GS977 said:
on my dash my gauge says 14.1 v 99% of the time never lower then 13.9v but i checked it at the batt and alt with it idling @1000 rpm and i get 17.25 v and 37 vac at the back of the alt. should i be concerned:confused
 
Basically that is what the alternator generates is AC voltage I believe. However it should pass through a regulation stage that consists of diodes to convert that voltage to a straight DC value.
 
I started working on alternators back in the 60s. Every voltage regulator setting I ever saw was 14.2 volts.
Glenn
:w
 
On the low side, I'm told that under 11 volts, the coil won't get enough voltage to properly fire the spark plugs and the fuel injectors also don't fire right. I had my alternator go up during the National Corvette Caravan... ON THE WAY DOWN. I made it home afterward, but it was dicey. Nobody had alternators for my car when I had access to places that were open... and the ironic thing was I had just bought a 400 (!) amp alternator off eBay and it was waiting on the front porch when I got home.

FWIW, I saw 10.3 volts at one point... the car did run like cr*p. Funny thing was that if you kept driving, most of the time it would self-correct.

[RICHR]
 
400 amp!:confused What are you running a Lincoln 225 Welder?? :D junk!!
 
It was a decent price, it's claimed to be a high-quality buildup of a stock GM alternator with aftermarket parts, and I figure it'll cover anything I want to throw at it - spare fans, the laptop, rallye lights or electric supercharger (just kidding!). And if I want to put a winch on the front to pull Rustangs out of snowbanks, or add a couple of electric motors to the front wheels and make it AWD, I'm all set!
[RICHR]
 
rrubel said:
It was a decent price, it's claimed to be a high-quality buildup of a stock GM alternator with aftermarket parts, and I figure it'll cover anything I want to throw at it - spare fans, the laptop, rallye lights or electric supercharger (just kidding!). And if I want to put a winch on the front to pull Rustangs out of snowbanks, or add a couple of electric motors to the front wheels and make it AWD, I'm all set!
[RICHR]

Don't forget , you can run a cord to the breaker box on the house if the power goes out. ;LOL;LOL;LOL and think of the killer stereo you can run .

Glenn
:w
 
Maybe you can hook up the 4000 watts, amp, volts, Dc modulator to the guy with the turbo Hayabusa. What a trip!


Better living thru chemistry
 

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