> Date: Sat, 15 May 1999 00:49:29 -0400
> From: "Edgar T. Kremer"
> Subject: Re:GMC: Alternators
>
> Automotive alternators don't need a "load", per se. If you consider the
battery
> a "load", this is true.
> The reason battery charging alternators destroy themselves is that the
sense
> wire from the alternator to the
> battery sends the battery voltage back to the alternator voltage
regulator. If
> the battery voltage is low, e.g. 12 volts, the regulator boosts the output
of
> the alternator until the battery "sends back" a voltage of approx. 14.1
volts.
> If there is no battery to "send back" a voltage, the output of the
alternator
> will continue to rise, eventually destroying itself.
>
>
> > Automotive alternators need a load present or you can blow output diodes
> > because voltage soars to a high value without a load present.
Edgar,
What is the battery if not a load ? It is connected across the automotive
alternator output and receives current from the alternator same as the
other appliances.
There are many variations of alternator and regulator circuits.
To be safe, I always consider the battery an important regulator circuit
component which should be in the circuit when an automotive alternator is
operating.
If an automotive alternator runs without load (and without battery), one
will soon find out if that particular alternator's field has enough
residual magnetism to exceed the diode peak inverse voltage rating.
Results may vary as voltage is proportional to alternator rpm.
Don Miller
75 Glennbrook project
Shenandoah Valley of Virginia
> From: "Edgar T. Kremer"
> Subject: Re:GMC: Alternators
>
> Automotive alternators don't need a "load", per se. If you consider the
battery
> a "load", this is true.
> The reason battery charging alternators destroy themselves is that the
sense
> wire from the alternator to the
> battery sends the battery voltage back to the alternator voltage
regulator. If
> the battery voltage is low, e.g. 12 volts, the regulator boosts the output
of
> the alternator until the battery "sends back" a voltage of approx. 14.1
volts.
> If there is no battery to "send back" a voltage, the output of the
alternator
> will continue to rise, eventually destroying itself.
>
>
> > Automotive alternators need a load present or you can blow output diodes
> > because voltage soars to a high value without a load present.
Edgar,
What is the battery if not a load ? It is connected across the automotive
alternator output and receives current from the alternator same as the
other appliances.
There are many variations of alternator and regulator circuits.
To be safe, I always consider the battery an important regulator circuit
component which should be in the circuit when an automotive alternator is
operating.
If an automotive alternator runs without load (and without battery), one
will soon find out if that particular alternator's field has enough
residual magnetism to exceed the diode peak inverse voltage rating.
Results may vary as voltage is proportional to alternator rpm.
Don Miller
75 Glennbrook project
Shenandoah Valley of Virginia
