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

Discussion in 'Tech/Mech General' started by scotjimland, Mar 12, 2010.

  1. scotjimland

    scotjimland Funster Life Member

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    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..

     
  2. Peter James

    Peter James Read Only Funster

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    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.
     
  3. scotjimland

    scotjimland Funster Life Member

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    thanks for pointing out my error :Doh: .. must be a senior day .. :Laughing:
     
  4. Larrynwin

    Larrynwin Funster

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

    scotjimland Funster Life Member

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

    Now that is significant..
     
  6. Snowbird

    Snowbird Funster Life Member

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    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.
     
  7. sedge

    sedge Funster

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

    Larrynwin Funster

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    Better sweat it out and open the windows with the Triton :Eeek::Eeek:
     
  9. scotjimland

    scotjimland Funster Life Member

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    Of course, economy should never take precedence over safety .....
     
  10. Linda and Steph

    Linda and Steph Funster

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

    scotjimland Funster Life Member

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    and the HGV trucks with more lights on the cab roof than Wembley stadium :Laughing:
     
  12. JayDee

    JayDee Funster

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    Indeed!:Doh: 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
     
  13. GJH

    GJH Funster Life Member

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

    Must have missed that budget :BigGrin:

    Graham
     
  14. imprint

    imprint Read Only Funster

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    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!!
     
  15. scotjimland

    scotjimland Funster Life Member

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    well, it gets tedious talking about A frames and gennies all day .. :Laughing:
     
  16. Spacerunner

    Spacerunner Read Only Funster

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

    scotjimland Funster Life Member

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



    put it under the accelerator pedal , that's what my old man told me .. and he was NEVER wrong :Rofl1:
     
  18. Pampasgrass

    Pampasgrass Read Only Funster

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    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!!! :Rofl1:
     
  19. Snowbird

    Snowbird Funster Life Member

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    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.
     
  20. Larrynwin

    Larrynwin Funster

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