Possible Answer Re: <VV> Alternator question

[FrankCB at aol.com]

Ned,
    15 volts is a bit high for the battery to take all  the time.  But, you 
say that the voltmeter shows 13.5 when the car is not  running.  If this is the 
indicated level hours after the car is shut off,  then your VOLTMETER is 
reading HIGH, since the normal battery reading  should be 12.7 volts.  That would 
indicate that your voltmeter is probably  reading 13.5 - 12.7 = 0.8 volts 
high.  So the 15 volts shown when running  the car is actually 15 - 0.8 = 14.2 
volts.  This is the perfect normal  running voltage to keep the battery fully 
charged, but not OVERcharged (although  it will read higher just after starting 
until everything is warmed up).  So  your charging system is likely to be 
operating just fine.  But to be sure,  compare the indicated voltage on your 
voltmeter with that of a more  accurate digital voltmeter (DVM or a DMM).  You can 
hook up the DVM to plug  into the cigarette lighter so you can see both gauges 
while the car is being  driven.  
    When I did that on my Minivan, I found that the  dashboard voltmeter that 
came from GM read almost a full volt LOWER than  reality.  I just take that 
difference into account when I'm driving the  Trans Sport.
    Most gauges can have their calibration checked  without using $$$ 
laboratory equipment.
    Frank "likes gauges" Burkhard
      
 
In a message dated 6/21/2006 12:26:44 AM Eastern Standard Time,  
AeroNed at aol.com writes:

Since I  installed the all important voltmeter in my Corsa coupe, I've   
discovered that the alternator is putting out 15 volts all the time. When  
the  car 
is off, the battery shows 13.5 volts. The alternator is  internal  regulated 
that is puts out something like 50 amps. It's the  rear of a unit from  a mid 
80 
GM car with a Corvair front and fan.  I'm not blowing lights or anything  but 
it 
sure seems like I need a  voltage regulator. What does the group of  experts 
think?   

Ned  Madsen