Testing high electrical use vs. Mpg
 

It's commonly known that your cars alternator increase its output and therefore load on the engine as it keeps up on the electrical demand of the car.

Has anyone tested mpg with high electrical load vs low load?

In early winter mornings, I'm driving with the heated seat on, rear defroster, blower on high, highbeams on...
I'm just curious to know what effect this has on my mpg.

As a side note, my car has electric power steering...that motor must be drawing a lot of current at low speeds!
I'm wondering about a cutoff switch to disable it at highway speeds...?

My load at idle went up 0.3% by turning the lights and heater on. I think that with a smaller engine you would see a significant increase in load running all your options.

Given the situation that you describe, you also have another big setback in MPG, which is delaying the motor from reaching full operating temperatures as soon as possible by running the blower on high.

So if you try to use a scangauge/ ultragauge to try and record the difference between the high and low electrical loads, be sure to factor in the warm up time.

good point :thumbup: On really cold days I put a space heater in my van in the morning. It is an oil filled one so it stays hot after I unplug and drive away. It is a small one, the same as this

at Idle, I burn an extra .10gph with the headlights on, brake lights on (brakes depressed) and the Heater on half speed with in-cabin recirculation. Unsure the differences at speed.

I suspect that your loosing more mpg just from the cold weather alone. I have an electric car, and when it is cold the range is noticeably different. From rolling resistance to air drag, cold hurts you. In my car I have a ceramic heater element I took from a room heater I bought at home depot. I re-wired it to run at 375 watts for low power, and 1125 watts at high power. I have a 120 volt DC battery pack, so using a 120 volts AC heater element worked very well. Between using the heater and the cold weather effects, I think my range is reduced by 1/3. I still get at least 70 miles range in the winter, but in the summer it's over 100 miles. I suspect that worrying about your electric load in cold weather is only a small fraction whatever mileage decrease.

I wouldn't worry about the electric power steering...it will only use energy if you're moving the steering wheel so it will not hurt you're fuel economy unless you're steering much (which you're not at speed)

I think for the most part its load is masked by the increase fuel consumption at cold start. An alternator can take 3 hp for a 70 amp load and its rather agressive at recharging the starter battery when you first fire up.

In a hybrid you can tell electrical loads. I disconnected my power steering that was electric and gains 2mpg. :eek: When your starter batttery starts to go you loose mpg and loose assist. :eek:

Interesting, I will have to see if I can do that on my Escape. I'll need a switch, though, to keep my wife happy.

One could argue that the extra load could be beneficial and reduce warm up time. If you have to get bad mileage the first few minutes, you might as well use it to get comfortable.

My MPGuino shows a difference of 0.03GPH (imp) with the lights on high beam compared to DRLs, which I think is about 200W. (Volvo 940).

Obviously that a fixed load on the engine, and will make less of a difference to MPG the faster you go and the engine may produce acceleration/torque more or less efficiently at different RPMs.