Why do ppl think that more electrical current draw == more drain on engine? - PeachParts Mercedes-Benz Forum

winmutt · #1 08-11-2006, 02:50 PM

I just noticed this in the post about the alternator. The alternator is always going to require the same amount of energy, regardless of how much is being put out.

janko · #2 08-11-2006, 02:52 PM

no.

winmutt · #3 08-11-2006, 02:54 PM

Quote:

Originally Posted by janko

no.

No? Thats the job of the regulator. The alternator is not going require more energy under higher load. The regulator ensure that the unused current is disappated. If the car is attempting to use more current than it rated for, it will either be unavailable or burn out the regulator if the engine is revved high enough to produce the required current.

janko · #4 08-11-2006, 03:08 PM

no again. think of it this way. if there is an electrical load, the alternator will offer some 'drag'. under a no or little load condition, the alternator presents less 'drag'. reluctant to use the word resistance in this electrical context.

winmutt · #5 08-11-2006, 03:20 PM

Quote:

Originally Posted by janko

no again. think of it this way. if there is an electrical load, the alternator will offer some 'drag'. under a no or little load condition, the alternator presents less 'drag'. reluctant to use the word resistance in this electrical context.

I disagree.
http://www.alternatorparts.com/understanding_alternators.htm

Looks like I'm correct. The alternator is always generating the same amount of current in synch with the RPM's of the engine. There is no additional load as the current increase, merely less current is disapated.

OMEGAMAN · #6 08-11-2006, 03:21 PM

The only job of the regulator is to turn on and off the field windings inside the alternator based on battery voltage and turn off the charge indicator light on the dash.
If you think there is no draw from the alternator turn on all the electrical accesories in your car and note the rpm drop.

winmutt · #7 08-11-2006, 03:32 PM

Quote:

Originally Posted by OMEGAMAN

The only job of the regulator is to turn on and off the field windings inside the alternator based on battery voltage and turn off the charge indicator light on the dash.
If you think there is no draw from the alternator turn on all the electrical accesories in your car and note the rpm drop.

The alternator is a magnet and a bunch of wires going around in a circle. If the wires were generating current (electro magnet) then it would cause the magnetic fields of the natural and electro magnet to interact with each other and perhaps add to the load on the engine.

[edit]
Ah see here I am thinking of a generator. So the alternator is an electromagnet and a stator. I see as the load increases the regulator increases the current in the electromagnet there by increasing the physical resistance of the rotor interacting with the stator. Now I see. How is this more advantageous than a generator? Heat issues with the disappation of the extra energy?