Daylight Headlamps

Why would you want fog lights without headlights? Plus as said before it's not always about how 'light' it is but about visability. At teh weekend I was travelling down the motorway with teh sun *just* below the houses, it was still perfectly light as the sun hadn't set. But now you have this huge bright light making the houses look black. All the cars in front of the houses looked black. All except teh ones with daylight running lights. Also happens for rain etc etc etc etc etc etc. Can't believe people would actually want these turned off.............

Turning them off is a vaild point. However,

Police cars run with their lights off - so not to have such a high profile, and enable then to nick some unsuspecting motorist "for your own protection Sir". If you notice on your travels most Volvo police cars have the lights deactivated. This also applies to unmarked cars as well, so my theory is keep them turned on so we Volvo drivers can identify the potential laser/mini-gatso/vascar users !!

As a matter of interest my high milage S 60 has gone through 5 dipped beam bulbs in 1 year. Why? I think its because they are on all the time and where I live (down a farm track that is unmade) when I return from a days work say 250 miles, the bulbs are so hot, that a bump in my lane simply breaks the filament. The same seemed to apply to my previous V 70 so I don't feel that it is a fault. I've tried the OEM ones and the Halfords variety, the only difference seems to be the price.

On another forum somewhere someone was talking about "heavy duty" bulbs with more robust filaments. What these are I couldn't say, but I can say all but my MR2 (pop up lights) ran with the headlights on all the time, whether they were DRL or not (my 440 is the only car I've had with DRL) and over 8 years and many 100's of thousands of miles I've replaced about 3 headlight bulbs. And one of those was simply as when I brought them for my 440 they only had 30% extra bright bulbs in the garage and I wanted both sides to match....

Stu

On the thorny subject of bulbs, I seem to have cracked the problem. Its easy and cheap. The last time a dipped beam bulb went on my S 60 I went to Halfords, its the only place with easy parking near to where I live, I'm not a Halfords fanatic or anything like that! honest. But I've noticed on a few Forum additions I seem to mention them. I had a brain wave - why not buy two bulbs! - I know, its difficult being a genius at times, however, it seems to have done the trick. 10000 miles later, still got the spare bulb intact in the glove box. On saying that I bet I get a bulb go soon!

[vjck_uk]

I have a s reg v40 and have disconncted the drl's on mine.
If send me a picture of your headlight wiring diagramm I might be able to tell you what to do.
Vaughan
vjck_uk

[vjck_uk]

Hi stu,
You are wrong about not using more fuel with the drl's on.
You get owt for nowt.
The electric has to be generated to run them and a generator producing power uses more and more power to drive it (ie fuel)
for the more power it produces.
You can verify this by switching various things on (on motors with a carb) and watching the revs drop and the engine note change.
If you have ever put jump leads on a car with a flat battery to start it ,when the leads are connected you just see the revs drop.
I would estimate the drl's cost around £25 a year on a mileage of 15000.
Years ago the A.A. did research and found that running around all the time with a roofrack on uses £20+ in petrol a year.
Another side effect is more pollution amd lets face it, can't you see other cars coming without drl's ?.
Of course the bulbs last a fraction of the time than for a car wthout drl's.
I've disconncted my drl's on my s reg v40 and on my other car a 88 240 it's just a fuse removal.
vjck_uk

How can you compare th etiny fraction of power a light uses with the tremendous increase in drag caused by a roof rack? If your revs are rising or falling with electric things then it needs an urgent serivce - as you are not producing enough power to keep your battery charged whilst moving. Even my 22 year old Spitfire manages to use all lights, inc rear fogs and other stuff like the heater fan, wipers and very powerful radio wound up without the revs moving.

Airco can cause thison very underpowered (or older) cars - but even this doesn't affect either my old 1.8 '96 440 (on a run to Leicester from Amsterdam it used no more fuel running with airco on all the time as without it at all) and my V40 is the same with the climate control. And even then that is a mechanical issue not electrical.

So no they don't use any more fuel. As for the environment - you drive a T4 don't you! Hardly the most environmentally friendly car is it!

As for burning out more as mike has said in a different post - he has replaced just 3 bulbs on his 5 year old car. You actually cause more damage to a bulb by turning it on and off then simply leaving it burning. I have always driven with my dipped lights on and only ever replaced bulbs once or twice in nearly 10 years of driving.

So the cost over a year of using DRL's on a car with good electrics should be zero. And in my experience has been...

As for the seeing other cars, as I mentioned in other posts it's not just poor light that is the issue it's trickly light conditions winter mornings / afternoons etc. Perfectly light but when the son is near to the horizon cars dissapear - all you can see are the cars with DRL's. So please people keep 'em burning.

Stu

Sorry Stu, but it is a fact of physics that you cannot get additional power for nothing. The question to be asked is how much does it cost and is this a significant amount to worry about. In between eating turkey over the last week, I have attempted to quantify the cost of DRL's. Looking at my car, the two dipped headlights are 55W each and there are 10 other minor lights which total 50W. Thus the increased load on the engine is 160W, which equates to 0.214HP.

If we assume that the average power put out by the engine is 50hp and this equates to 30mpg, then the increased power of 50.214hp will increase the fuel consumption, pro rata, to 30.13mpg. On an annual mileage of 12,000 miles, the extra fuel consumed will be 7.766litre, which at a cost of £0.75/l, equates to £5.90 per year. Obviously, this figure will vary depending on driving style and assumes all your driving is in daylight. As you will need your lights on anyway when dark, or in adverse road conditions, the potential saving by switching your lights off is much less - say £3 per year. Compared to all the other costs of running a car, this is very insignificant to most people.

As for aircon, this requires much more power, maybe 4 or 5 times more, but I remember reading a test report done in the States some years ago, where they compared two identical cars, one with aircon and the other running with windows open without aircon. The one with the aircon was actually more economical. The reason being that opening the car windows causes buffeting of the airflow and increases drag on the car, which is greater than the increased power consumed by the aircon.

I hope this is of benefit to you all

Brian Ingle

[volvo2]

I prefer the older 30% day running lights. Having the headlights full on all the time is certain to shorten their life.

Melvyn