lower wattage light bulbs

[oil pan 4]

Originally Posted by serialk11r

Uh, that is definitely not a 'typical' electrical load on a car, unless you have a 2000 watt sound system. I did a bit of research into this trying to figure out how whether off the shelf thermoelectric generators could generate enough electrical power for the car. 300W is a typical electrical load, comes out to maybe 0.75hp at the alternator.

Don't forget about the drag produced by the little fan in the alternator while its spinning at 3 times crank shaft speed.

[johnathanf1lm]

I meant for where old tele man got the 2 to 5 horsepower from. I wonder the effect a 500 watt sound system has on fuel economy.

[serialk11r]

Originally Posted by oil pan 4

Don't forget about the drag produced by the little fan in the alternator while its spinning at 3 times crank shaft speed.

That's part of the alternator's mechanical efficiency no? Everything I've read discussing alternator efficiency includes the cooling losses..

Originally Posted by johnathanf1lm

I meant for where old tele man got the 2 to 5 horsepower from. I wonder the effect a 500 watt sound system has on fuel economy.

The thing with electrical load is yes it puts more load on the engine but the more load on the alternator the more efficient it is, and the more load on the engine the more efficient it is so I think at the end of the day it's probably not that big of a deal.

I don't ever use the sound system though, so I'm just talking out of my ass :P

[redpoint5]

Originally Posted by johnathanf1lm

I meant for where old tele man got the 2 to 5 horsepower from. I wonder the effect a 500 watt sound system has on fuel economy.

Your 500W sound system doesn't draw that continuously. My wild guess is that it averages 120W, which is like running an extra pair of high-beams. Double that number (due to inefficiency in converting mechanical energy into electrical) and divide by 746 (electrical equivalent of 1hp), and you get 0.32hp extra load on the engine.

[gone-ot]

...and, automotive DC heater fan motors are NOT very efficient at all either, so consider how much load there might be during either:

(a) driving at night with A/C and stereo blasting.

(b) driving at night with heater and stereo blasting.

[redpoint5]

Originally Posted by Old Tele man

...and, automotive DC heater fan motors are NOT very efficient at all either...

My Dodge Ram uses a resistor to vary the fan speed, so this is a very inefficient design even when running the fan on low. I'm not sure how other makes and models vary fan speed, but I would assume the same way.

[serialk11r]

Originally Posted by redpoint5

My Dodge Ram uses a resistor to vary the fan speed, so this is a very inefficient design even when running the fan on low. I'm not sure how other makes and models vary fan speed, but I would assume the same way.

Holy **** really? I am going to check the circuit next time and replace with PWM if it's controlled by a resistor.

[Weather Spotter]

when I turn the fan on while costing it drops voltage = to turning the head lights on. speed of the fan makes little difference in power draw so I pulse and glide the fan on when the engine is on. bump the engine and start accelerating, reach down and turn fan on high. Kill engine then kill fan too. When the engine is off the coolant is not pumping so why run the fan?

[gone-ot]

Originally Posted by redpoint5

My Dodge Ram uses a resistor to vary the fan speed, so this is a very inefficient design even when running the fan on low. I'm not sure how other makes and models vary fan speed, but I would assume the same way.

...exactly my point, LOT's of power gets "wasted" heating that resistor up very HOT.