Do Alternators Change in Engine Load?
 

I've seen more than one person recommend the reduction of electricity consumption (stereo, lights, etc.) as an FE technique. I thought the alternator's load on the engine was a constant factor, and if so, those recommendations do not make sense to me.

Is the alternator's load on the engine different, depending on how much electricity the vehicle is using?

Lane

Yes it is. The magnetic field within the alternator is controlled by altering the amount of current through it. If this didn't happen, idling your car with your lights and stereo off would overcharge your battery.
If you want quantifiable evidence of the variable load electronics put on your car, ask someone with a huge stereo to take you for a ride. If they turn on their amplifier while cruising, you feel the hit the car takes (almost like turning on the a/c).

My Cavalier has those daytime running lights that never go off. I have been meaning to kill the damn things. Need to do that soon.

Thanks for the education, guys. I was thinking it was like my solar panels and batteries, where the maximum juice comes into a controller that varies what goes to the batteries.

Lane

If leaving your drl's on prevents 1 accident in your entire life, it will pay for the minute droplets of fuel used to run them. Be smart, drive safe.

You might quantify it a little better than "minute droplets".

Let's say you have 75 watts worth of DRL, that is equivelent to 1/10 of a horsepower, plus it comes through your alternator so it is probably more like 1/5 hp to run the DRLs.
I think we need more efficient lighting (but not blue please). If you consider there are about 125 million cars on the roads in the US alone, that would be 25 million horsepower to run DRLs on all those cars!

They don't do so good a job preventing accidents with other cars but they do seem to help out bikers and pedestrians a bit (AFAIK)

Give me the value of a dead pedestrian and I'll crunch the numbers to see if they are worth it for you...

There is no end to that sort of logic though. How much would it cost to wrap everyone in foam rubber? How many lives would it save? Eventually we WOULD all never leave the house.

the average american human life is valued at i believe $6.9 million dollars. (gov't calculations) :thumbup:

No, there's an end to the logic.. if it was hypothetical, and you thought people were worth infinate money, then there's no end. Lets take 6.9 million dollars. That buys about 6 million litres of gas. That powers my DRLs for a long time. Drive smart, be safe.