Alternator volts output
Thread Starter
Safety Car
Joined: Jun 1999
Posts: 3,570
Likes: 3
From: Austin, Singapore, Kuala Lumpur, Houston, Dallas, Hong Kong, Elgin, etc.. Texas
Alternator volts output
A friend of mine is concerned about the volts reading on his 1995 Corvette. Mine only varies a few tenths of a volt from 14.4v but his jumps around between 13.8v to 15.0v. The Helms manual says 13-18volts is normal which is not a lot of help. That seems very high to me.
What is everyone seeing on their digitial read outs?
[Modified by Mez, 10:17 PM 1/20/2003]
What is everyone seeing on their digitial read outs?
[Modified by Mez, 10:17 PM 1/20/2003]
Drifting
Joined: Jun 2001
Posts: 1,997
Likes: 1
From: Lake Ozark MO
Re: Alternator volts output (Mez)
Not enough info on when your friend is seeing a voltage sag, but you'll definitely see minor variations when the fans kick on, when the A/C clutch engages, AIR pump, etc. Once eveything has settled out I normally see 14.4-14.7 on my gauge.
But any reading over 12.7 I'd think is OK... But I'd keep an eye on it. You should normally see voltage readings over 13 with a decent battery.
[Modified by Dan Parker '96, 10:21 PM 1/20/2003]
But any reading over 12.7 I'd think is OK... But I'd keep an eye on it. You should normally see voltage readings over 13 with a decent battery.
[Modified by Dan Parker '96, 10:21 PM 1/20/2003]
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
Re: Alternator volts output (Dan Parker '96)
With the engine idling and a heavy electrical load, you can see the voltage drop to 12, but underway the voltage will be around 14.3 volts engine cold and as the alternator warms up the voltage will drop to 13.3 or so. The alternator cannot deliver full current rating at idle speed and is why the voltage to sag at stoplights etc. Its nothing to be concerned about because you spend little time idling.
Instructor
Joined: Aug 2002
Posts: 131
Likes: 0
From: Camarillo CA
Re: Alternator volts output (Mez)
A friend of mine is concerned about the volts reading on his 1995 Corvette. Mine only varies a few tenths of a volt from 14.4v but his jumps around between 13.8v to 15.0v. The Helms manual says 13-18volts is normal which is not a lot of help. That seems very high to me.
What is everyone seeing on their digitial read outs?
[Modified by Mez, 10:17 PM 1/20/2003]
What is everyone seeing on their digitial read outs?
[Modified by Mez, 10:17 PM 1/20/2003]
Safety Car
Joined: Aug 1999
Posts: 3,750
Likes: 1
From: San Jose CA
Re: Alternator volts output (Mez)
For what it is worth, when mine was kicking up above 14.4 - 15, the alternator was dying a slow death. Over time it was closer to 15 and the dash and headlights started flashing at idle, then the starter would turn very slow. Took the alternator in for a test and it was beyond bad.
I would get the alternator tested.
I would get the alternator tested.
Race Director
Joined: Oct 2001
Posts: 19,653
Likes: 428
From: Melbourne Florida
Cruise-In IV Veteran
Re: Alternator volts output (Grzldvt)
:iagree: Mine was jumping around too...pulsing dash lights made my interior look like a disco.... put in a new HD (140 amp) alternator...problem solved.. 14.3 steady.. good luck
Safety Car
Joined: May 2002
Posts: 4,010
Likes: 26
From: Somewhere nowhere
Re: Alternator volts output
my alternator runs as high as 15.1v when cold. that is normal.
14.7 is the speced output, but a volt either direction is acceptable.
every car I have ever seen drop at least a volt under load.
14.7 is the speced output, but a volt either direction is acceptable.
every car I have ever seen drop at least a volt under load.
