Voltage drop reading on guage '83 Coupe - clarification

Ben Swann benswann at comcast.net
Thu Feb 5 11:14:04 EST 2004


Alternator is working fine as best as I can tell.  There is good voltage at the battery as measure by a voltmeter, eg. 13.8 when engine is running.

Perhaps I should have clarified - alternator is putting out, which is why I measure 13.8V at the battery when the engine is running.  Voltage as measured at battery is 12 when engine not running.

This car has not required external charger and starts/run cycle indefinately with normal alternator charging.

I am referring to the voltage drop as measured at the voltmeter in the console with respect to what I read with a VOM at the battery.

  [----- Original Message ----- 
  From: Robert Myers 
  To: Ben Swann 
  Sent: Thursday, February 05, 2004 11:04 AM
  Subject: Re: Voltage drop reading on guage '83 Coupe

  No.  This is not normal.  Not if the engine is running at anything above idle.  The alternator output is insufficient.  It could be as simple as a slipping belt.  It may be the voltage regulator going out.  Perhaps a bad diode.  It might be burnt out or shorting coil windings.  Whatever, it should be fixed.

  At 10:56 AM 2/5/2004 -0500, Ben wrote:

    Subject: Voltage drop reading on guage  Vehicle:  '83 Coupe possibly others.

    Is it normal for the voltage reading on guage to read about 1-2V lower than battery voltage when accessories are turned on, in particular the climate control fan?    This car registers significantly lower on the voltmeter than at the battery.  

    Battery reads 12V with engine off.  13.7V +/- .3V varying at idle.

    Voltmeter reads: about 11.5 with engine off.  Engine on, no accessories around 12.3.  When flasher operated, there is a noticable flicker in the guage needle.  As other accessories are turned on, the flicker becomes more pronounced.  With lights on, guage reads around 11.5 and when fresh air fan is on full, down around 10.5.

    I know this is probably not a significant problem, but is there any good workaround?


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