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Re: Ammeter Oddity

To: Jay_Laifman@countrywide.com
Subject: Re: Ammeter Oddity
From: "Steven L. Finberg" <w1gsl@MIT.EDU>
Date: Tue, 28 Nov 2000 15:23:26 -0500
Hi Jay 

It sounds to me like you moved a couple wires in doing your header
instalation.

I think your alt and battery are just fine but the Ammeter is
in the wrong part of the circuit. 

A few simple tests first..

   Is the battery voltage coming up to about 13.8 V with the engine runing?
   and With the lights on?
   Does the engine start easily?  

If all of the above are true the Battery and Alternator are doing just fine.

Now to test the ammeter,  With the engine stoped, turn on the headlights,
the Ammeter should read ~ -18A.  

        If it reads ~ +18A the ammeter is connected backwards
                just reverse the terminals.

        If it reads zero (same as with the lights off) and
                has any other reading with the engine running
                you have it wired in series with the alternator.

It should instead be wired in series with the battery and load, less the
starter..

Here is the correct electrical hookup.  Its a bit cruder than I 
like but such are the limits of ASCII art.

              a               +    b
         -----O-----  Ammeter -----O----- car ignition, lights etc
        |     |                    |      
        |   solenoid               |
      + |     |                   Alternator
       Bat    |                    |
        |   Starter                |
        |     |                    |       
       ---   ---                  ---
        chassie  ground

     Ammeter hookup --- Negative Ground

Unfortunatly there is no factory standard Ammeter wiring, it seems they were
all installed as dealer options, so there is tremondious varation
in the exact hookup... :-(   It didn't even appear on the Rootes
Alpine schematic...

In a car without an alternator all the wires connected to terminals a and b
above are connected at terminal a, which is one of the 3/8" lugs
on the starter solenoid.  When I added an ammeter to my series V, 
to create a terminal b, I added a 3/8" bolt and fiber spacer 
connected to terminal a. That way  I didn't have to make any 
splices in the factory wiring.

                Steve F


*******************************************************************************
Steve Finberg                        W1GSL                       w1gsl@mit.edu
PO Box 397082 MIT Br        Cambridge MA  02139-7082              617 258 3754
*******************************************************************************

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