At 05:31 PM 4/9/98 -0400, you wrote:
>
>I have been following the TR6 alternator thread with interest. My TR4A
>(currently
>in restoration) always _seemed_ to run at a discharge when driving at
>night. The
>AMPS meter seemed to go ever so slightly negative, and the turn signals
>would
>make it flick a little more negative as the signals blinked on. I never
>noticed the
>Ignition light coming on in any way.
>
>Two questions. 1) Is it normal for the lights to bring the charging
>system close to
>discharge? Maybe my regulator isn't doing its job. 2) If the drain on the
>electrical
>system exceeds the output of the alternator, should the ignition light on
>the dash
>definitely come on? I never really knew what it was that made the light
>come
>on/go off!
Tony,
The typical alternator light is connected between the alternator and the
battery. It is typically a 12 volt lamp. It lights when you first turn
on the switch, befor the engine is running because the battery is high and
there is no voltage being generated by the alternator. When the engin is
turning and all is right with the world the alternator is producing voltage
ABOUT the same as the battery so the DIFFERANCE is small. There will be
some current in the lamp but not enough for it to light. You only get a
glow when the voltage differance is large enough to cause heat enough in
the bulb to glow. This should start in at about 4 volts differance.
So you could have a bad battery that was drawing too much current and
causing a drop accross the car wiring so that the lamp would glow and the
problem would be the battery, even though the Alternater lamp is
indicating. Generally you will not get any light within about + or - 3
volts of differance. The alternator could be putting out 14.7 VCD and the
battery is at 12 (low) there would be no light. The alternator could be
loaded down to 12 volts by a heavy load of lights and such and the battery
might be at 13 volts. Again no light and everything is fine. Only when
something is way off will you get a light.
(By the way it is important to have the corrent lamp in the socket to get a
meaningful indication)
Thomas Howard
'72 GT6, (and a good bit of USA Iron)
Lakeside Union School District
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