Driving with Headlights On .. how much fuel do they use ?

[scotjimland]

I've often wondered how much extra fuel is used when driving with headlights on ..
2 x 65 watt headlights
2 x 21 watt tail lights
2 x 5 watt number plate lights
plus side running lights.. and front side lights.. another 20 watt

adds up to 200 watts .. or about 15 amps , which equates to just over 1/4 hp.

But how much fuel does this use ? Not an easy calculation with so many variables..

anyway.. with this thought, I did a search and found a very interesting paper on the very subject which goes into it in greater detail .. http://mb-soft.com/public/headlite.html

Conclusion being that it does use a small but significant amount of fuel.. but is it worth worrying about.. ?

How many thousands or millions of cars have headlights on without choice and how much does this all add up to ?

I found this on an American motoring forum.. makes you think..

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.

 

[Peter James]

Small point but the tail lights will only be about 5 watt (+ 21 watt for the brake lights)

(Now that the British International Haulage Industry is going the way of the British Merchant Shipping industry and being taxed off the road) I tend to think of all the left hand drive lorries on our roads who probably can't see me in their mirror without my headlights on.

But yes I agree lights do waste fuel when you don't need them.

 

[scotjimland]

Small point but the tail lights will only be about 5 watt (+ 21 watt for the brake lights)

.

thanks for pointing out my error oh: .. must be a senior day ..

 

[Larrynwin]

This is probably insignificant compared to increased consumption by the use of airconditioning

 

[scotjimland]

This is probably insignificant compared to increased consumption by the use of airconditioning

Indeed, a car a/c unit is a lot more, only guessing, probably around 4hp .. ?

Now that is significant..

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[Snowbird]

Good point, The bracket broke on the aircon pump on my Isuzu trooper a couple of months ago,so I took it off,even though the pipework was already disconected.
I put shorter drivebelts on to drive the power steering.
Could not believe the diference in fuel consumption...now getting extra 60 miles to a full twin tank of fuel.
OK I do carry 200ltr of fuel,but its still a hell of a saving.

 

[sedge]

Not only 4+ wheeled vehicles - and any motorcyclist that values his or her life of course!

 

[Larrynwin]

Better sweat it out and open the windows with the Triton

 

[scotjimland]

Not only 4+ wheeled vehicles - and any motorcyclist that values his or her life of course!

Of course, economy should never take precedence over safety .....

 

[Linda and Steph]

I can now have happy thoughts thinking about how much it's costing the idiots who drive around with their fog lights blazing

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[scotjimland]

I can now have happy thoughts thinking about how much it's costing the idiots who drive around with their fog lights blazing

and the HGV trucks with more lights on the cab roof than Wembley stadium

 

[JayDee]

I can now have happy thoughts thinking about how much it's costing the idiots who drive around with their fog lights blazing

Indeed!oh: I've found foglamps to be of dubious benefit except when driving the narrow Devon lanes. I then find that, particularly in clear weather, they illuminate the hedgerows and banks very well and give a lot of help with road position and suchlike. Of course driving with foglamps when visibilty is not reduce by inclement weather is prohibited, but good sense should prevail.:thumb:


John

 

[GJH]

Small point but the tail lights will only be about 5 watt (+ 21 watt for the brake lights)

(Now that the British International Haulage Industry is going the way of the British Merchant Shipping industry and being taxed off the road) I tend to think of all the left hand drive lorries on our roads who probably can't see me in their mirror without my headlights on.

But yes I agree lights do waste fuel when you don't need them.

When did they tax the British Merchant Shipping Industry off the road then?

Must have missed that budget

Graham

 

[imprint]

Snowbird "..now getting extra 60 miles to a full twin tank of fuel.
OK I do carry 200ltr of fuel, but its still a hell of a saving. "

You're saving the same amount of fuel no matter how full the tanks are, mon vieux.

Now let's have an argument about whether it's worth lugging around 100 litres of fuel you don't need. Look up what fuel weighs per litre, multiply that by 100, work out the weight of the van, take away the number you first thought of.... oh the Funsters will keep this running, so factor in the global warming caused by this debate's hot air, we'll be here till well into the New Year... watch it, Jim Lad!!

 

[scotjimland]

the Funsters will keep this running, so factor in the global warming caused by this debate's hot air, we'll be here till well into the New Year... watch it, Jim Lad!!

well, it gets tedious talking about A frames and gennies all day ..

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[Spacerunner]

So if I changed all my running lights to LED's will that save me fuel ?

 

[scotjimland]

So if I changed all my running lights to LED's will that save me fuel ?

not so you would notice ... a tennis ball would save move fuel ...



put it under the accelerator pedal , that's what my old man told me .. and he was NEVER wrong

 

[Pampasgrass]

Weight of fuel

Why run with full tanks of fuel?

A gallon weighs approx 6 lbs so you are really carrying around excessive load which

makes the usage of your lighting insignificant!

30 gallons equals approx 180 lbs equals approx 12.5 stone equals another passenger.

How much water do you carry?

Do you use lightweight gas bottles?

Air conditioning units, are your windows down?

Tyres at correct pressures and tracked correctly

Finally tuck in behind an artic , you won't end up where you planned to go but you will

get at least 80 miles per gallon!!!

 

[Snowbird]

Snowbird "..now getting extra 60 miles to a full twin tank of fuel.
OK I do carry 200ltr of fuel, but its still a hell of a saving. "

You're saving the same amount of fuel no matter how full the tanks are, mon vieux.

Now let's have an argument about whether it's worth lugging around 100 litres of fuel you don't need. Look up what fuel weighs per litre, multiply that by 100, work out the weight of the van, take away the number you first thought of.... oh the Funsters will keep this running, so factor in the global warming caused by this debate's hot air, we'll be here till well into the New Year... watch it, Jim Lad!!

I know I would get a bit more MPG if I didnt carry the weight of fuel that I do,but I do run on homemade biofuel at 30p per litre. The reason for this is that I make regular runs to my wifes family in Amsterdam and dont have to buy diesel on the road.
The RV is also fitted with long range tanks so that I can make Spain without having to buy diesel in France. 30pence a litre makes it all worthwhile,and as well as saving the planet am saving my wallet...which is much more important.

 

[Larrynwin]

I'm getting extremely worried about all this economy, I only have thirty bob a week for fuel

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[Snowbird]

I'm getting extremely worried about all this economy, I only have thirty bob a week for fuel

Have just the thing for you....check out my photos....Solex does about 150 MPG, even thats fitted with a long range fuel tank.