Hello,

Perhaps you don't really want an ammeter.

The problem that you are having is the result of having to put the gauge in 
the charge/discharge circuit.  The posts have rightly pointed out many 
problems with doing this.

Now, I'm ancient, and I have always liked the ammeter idea.  However, most 
modern cars that have any sort of charging gauge now use a voltmeter.  When 
I first was exposed to that, I rebelled, saying that I wanted to know the 
charge/discharge current, not the voltage.  Well, experience and reflection 
has brought me around.  The voltmeter directly indicates the charging 
voltage, or at rest voltage, both of which tell a lot about the battery and 
charging system, and neither of which could be gotten from an ammeter. 
 Plus, by inference (turn on everything in the car) the battery voltage 
reflects the current capability of the generator or alternator.  The bonus 
is that the voltmeter can be 50 ft from the battery and have one small wire 
leading to it.

Mike

Michael A. Radtke  -  Z74               Voice: 602-862-4897
Bull                                      FAX:         4853
13430 N. Black Canyon Hwy.
Phoenix, AZ  85029                      Email: m.radtke@bull.com