MAX Update No. 86: How Headlights Affect MPG


| 12/26/2011 11:56:37 AM


086LiquidLightHere’s another goofy graphic, fraught with symbolism; no, MAX’s headlights don’t have a fuel tank of their own, I’m just trying to make a point.

As one approaches three-digit fuel mileage—100 mpg and above—little things start making a big difference. Things you’d never notice in a 20 mpg car are spectacular in MAX.

For example, I have a switch on the dashboard that I could label, “More than 100 mpg” in the middle position, and “Less than 100 mpg” in the top and bottom positions. Or I could just label it “Headlights.”

Up is high beam, down is low beam, center is no beam.

The better your mileage, the greater (worse, actually) the effects of your electrical auxiliaries. Your headlights, your heater fan, even your radio, they all consume fuel (via the added engine power to drive the alternator harder to produce the extra amps) at a fairly steady rate…when they're on, that is.



Many folks think that car alternators have a steady load and produce a steady amount of electrical power. We read it all the time in promotional literature for on-the-fly hydrogen generators, those that claim “…your alternator’s excess electricity…” as their power source. Well folks, there’s no such thing as “excess electricity” from an alternator, no leftover electricity that’s going to evaporate if you don’t use it for something. Alternators convert engine power to electricity, and the more electricity you demand from the alternator, the more power the alternator demands from the engine.

ABBEY BEND
1/13/2012 9:44:42 PM

One more thing, the 1156 bulbs will not meaningfully interfer with your headlights performance when using them at night, they will just shine through the glass, with possibly a small faint shadow from the filament posts, which you will have to look for to see.


ABBEY BEND
1/13/2012 9:42:02 PM

Jack, By placing the 1156 in front of the headlight, the headlight reflector keeps it from operating as a true bare bulb. A 1156 operates at 27 watts, makes about 402 lumens which is relatively bright, they are only running lights after all, and the headlight reflector behind them, directs the light to a certain degree, making them appear brighter than they actually are. http://www.ehow.com/list_7615668_1156-incandescent-lumen-specs.html H6024 lamps operate at 55 watts each on low beam, 65 watts each on high beam, and without the tail lights burning 1157s at 8.3 watts each, your wattage savings is about 72.6 watts, or around 57 percent savings. Total wattage of your headlights on is about 126.6, wattage of only two 1156s on is about 54 watts.


Anonymous
1/9/2012 11:36:30 PM

I stand corrected. I discussed this with my buddy who's been teaching electrics/electronics for Case IH for many yrs & says the increased magnentic load in the alternator as an accessory is switched on can account for as much as 50rpm increased load on the engine. For a vehicle running @3000rpm, that's in the range of 1%. For a typical car getting 20mpg, it's insignificant. For your application, that's another mpg.




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