-=> Jay Emrie said to Greg Mayman
 -=> about "VEHICLE LED'S" on 10-15-03  22:54.....

 JE> Just a simple question. Why do the great majority all the diagnostics
 JE> specify voltage readings rather than current readings in trouble
 JE> shooting alternators in official manufacturer's vehicle shop manuals?
 JE> :-)

In general when alternators are on test in the workshop, there
are three things that are looked for:

(1) that there is output voltage as the speed is increased past
    the nominated minimum speed;

(2) that the regulator will stabilise the output voltage at the
    required value; and

(3) that the alternator can continue to produce this voltage
    while it is delivering increasing current into a load.

These factors are tested by watching the output voltage as you
gradually increase the speed, and then as you switch in resistive
loads.

But when you're charging a battery, the battery can maintain a
voltage even when the alternator is putting out zero current.

Any dumbo should know that an ammeter reading zero means no
current flowing into the battery.

But a voltmeter that reads 12 volts... It's a 12 volt battery, so
everything must be alright, mustn't it?

From Greg Mayman, in beautiful Adelaide, South Australia
   "Queen City of The South"    34:55 S  138:36 E

... Enjoy your life; be pleasant and gay, like the birds in May.
___ Blue Wave/386 v2.30

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