Bruce,
An ammeter (amp gauge) will tell you immediately if something is wrong. The
needle in the positive zone indicates that amperage is flowing into the
battery. That tells you that the voltage regulator and your generator (or
alternator) are working. If your battery is found to be dead on occasion and
your
ammeter is always in the positive zone while the car is running, this
typically
indicates that your battery cannot hold a charge and hence the battery is the
most likely the problem* . When the ammeter stays in the negative zone, this
indicates the battery is discharging. This typically indicates a faulty
generator (or alternator) or voltage regulator. When you see an ammeter in the
negative zone it is only a matter of time before your battery will be dead,
but
in this case the battery is most likely not the problem, since the battery
is not receiving a proper charge while the engine is running.
A dashboard volt meter, on the other hand, only tells you the present
condition of your battery and is not much help in making a diagnosis as to why
your
battery continually drains. Is it a charging issue (bad generator or voltage
regulator) ?? Or is it that the battery cannot hold a charge for long and
therefore the battery is defective*. Making the correct diagnosis on a
dashboard voltmeter is difficult.
I personally prefer an ammeter over a dashboard voltmeter for the reasons I
stated above. For me the ammeter provides greater value since it gives more
information as to what is happening as the car runs. I hope this helps....Tony
*Providing you don't have wiring trouble, short circuits, or lights that
remain on when the car is off
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