Headlight use effect on MPG?

check out the facts at

Good question. It takes about 1/4 HP (give or take) of extra energy input to alternator to power lights. Given the efficency of a gas motor that means in theory about a approx 2 to 4 extra ounces of fuel a hour or so on your V10 or maybe 1/10 th a MPG (at most) or less. It is a good point though in that when you consider the millions of cars on the road daily with them that together they could "waste" maybe

500,000 to 1,000,000 gallons of fuel a day (broad range is because of a guesstimate of units on road) This equals about 12 to 24,000 barrelas of fuel a day or 4.5 to 9 million barrels a year. To put a different perspective on it, this is also equal to about 25 to 50,000 semi tankers trucks of fuel a year or about 140 tanker truck loads a day.

----------------- TheSnoMan.com

An independent estimate is easy to do - If you know the wattage of the lamps.

100 Watts is 341 BTU/hr. Gasoline contains over 100,000 Btus per gallon, but your engine is only 30% efficient. Let's just call that 30,000 Btu's per gallon that you can use. So 100 watts is going to cost you 341/30,000 = .01 gallon per hour.

MPG math is hard to do, because it's not a consumption figure. Let's do it this way: If you drove an hour at 70 mph and got 12 mpg, then you'd be burning 5.833333 (lots of 3's) gallons per hour. Add the.01 and you have

5.84 gallons per hour, over 70 miles. 70/5.84333333 That comes out to 11.98 mpg.

So in that case 100 watts is about .02 mpg

Facts?? That link is to a bunch of pure BS.

Al

Holy crap. I'm charging my cell phone at home from now on:)

Al

I bet you do not believe in global warming either nor that oil supply is limited. Thats the problem when you cannot "think outside your box'

----------------- TheSnoMan.com

Not bad logic but 30% is a bit to generous at cruise and your do not consider that alternator is not 100% efficent either. BTW gas has from about 115,000 to 125,000 BTU's to a gallon so we will average it at 120,000 (the lower number is E10 or 10% alchol) There is about 2800 BTU in a HP to. If your vehcile uses say 40 HP to cruise figure on 40 times 4 (averaging 25% efficency) or 160 HP input needed. next 160 x

2800 equals 448000 BTU's needed or about just under 4 gallons a hour. If we take that engine is susing approx 500 ounces of fuel per hour (128 x 4) and factor in about 4 more ounces for another 380 BTU/hr (120,000 dived 128 equal BTU per ounce) The added usage in this senerio would be about .8% or less (4 oz / 500 oz) so at say 15 MPG (assuming 60 mph cruise at 4 gallons a hour) it would be around or under .12 MPG. (15 x .8%)

With a car that gets 30 or 40 MPG it would be more noticable because the energy needed for lights would be constant but a smaller car woul need less to roll and use less fuel and when you used say 2 GPH or 256 oz you would divide 256 into 4 and get 1.5 % or about a .45 MPG or less penalty at 30 MPG.

----------------- TheSnoMan.com

"(The energy required to power the DRLs is not free. It is not surplus energy that is just "available" from the vehicle's engine. Various estimates place the reduction in overall fuell efficiency at 0.25 - 0.5 mpg, and cost estimates range from $5 - $15 per year. GM estimates the annual cost of DRLs at less than $10 per vehicle per year.)" I copied that from the lightsout site and those numbers are in line close enough with other numbers figured here in this post so the site isn't 'PURE' bs is it?

>

This coming from you. Well, thanks for allowing me to answer you BEFORE you crucify me. My head is in a box and yours is way up your ASS! By the way, how much is the bet and when do you pay me.

Al

On Sun, 08 Apr 2007 12:10:31 -0700, Big Al rearranged some electrons to form:

Al, don't pay any attention to SnoBlower. You can't fix stupid.

Complete crock of shit. There is LOTS of evidence that DRLs work. Using High Beams for DRLs is questionable, but DRLs as a generally good diea have ample support, even within the USA.

He's over in the Jeep group now, spewing his usual shit.

yippee.

Spdloader

Link to the evidence? I thought not.

Q. Will DRLs reduce fuel economy?

A. Yes. The energy required to power the DRLs is not free. It is not surplus energy that is just "available" from the vehicle's engine. Various estimates place the reduction in overall fuell efficiency at 0.25 - 0.5 mpg, and cost estimates range from $5 - $15 per year. GM estimates the annual cost of DRLs at less than $10 per vehicle per year. Multiply that by 200 million vehicles in the US, and you can see why we oppose mandatory DRLs. The cost of DRLs over several years cannot possibly justify the benefits, especially the the benefits are in serious doubt. Given the increasing price of gasoline, the economic impact of DRLs will only get worse. Further, the combustion of the additional gasoline required to power the nation's DRLs will result in several billion pounds of pollutants being exhausted into the atmosphere. What makes the federal government's position on DRLs seem so strange is that the Environmental Protection Agency allows GM to disconnect DRLs before testing! Why?

Virtually Nill

ACTUALLY, your "virtually nill" could amount to over a billion, YES billion dollars a year. Read this:

Mathematicians/Statisticians can make a case for anything. This is in the realm of: "If you can't dazzle 'em with brilliance, baffle 'em with bullshit"

The wallet-effect(MPG) on a persons vehicle having DRLs illuminated is exactly what the man posted....virtually nil.

Dave S(Texas)

Boy this would be hard one to prove, but I am willing to take a shot at a rough estimate:

Say the DRLs consume 40 watts. Assume the average fuel to DRL conversion efficiency is 25% (and it is not this good). Assume the average person drives 12,000 miles a year and that 65% of this is at times when lights are not otherwise required. Assume the average speed is 35 mph (including highway, town, stop and go). I get the following results -

Total hours of DRL usage = 12000*.65/35 = 223 hours (could be a lot more, or somewhat less)

Energy expended by DRLs = 40*223 = 9 kwh (could be half this or twice this)

Energy consumed to power DRLs = 9 kwh/.25 = 36 kwh = 122,000 BTUs (range is probably 50,000 to 500,000)

1 gallon of gasoline = 114,000 BTUs

Running DRLs for 1 person for one year = 1.1 gallons of gasoline but the range is probably 0.1 to 10 gallons of gasoline. Given today's price of gasoline, that means drivers are probably paying from $0.30 to $30 per year to run DRLs, not including bulb replacement. So, for an individual, DRLs are not all that significant. However, there are over 200,000,000 million cars in the US. If they all had DRLs, that would mean an annual use of over 200,000,000 gallons of gasoline to keep the DRLs illuminated. That would be over a half a billion dollars.

Ed

Its all a scheme by the

wait for it

illuminati.

Dave