One for the 'electronic wizards' on here

[Tin Can]

I have 2 x 30watt front foglamps on my car and want to have them on in daylight hours as day light running lights for increased safety. I will wire them from a fused feed via a change over relay so that when the side lights come on they automatically switch off and then revert to there normal use of fog lights used as and when. My problem (i think) is that when they are on as DRL's there is a back feed potential so i was thinking of wiring in a couple of blocking diodes, so my first question is how do i calculate the value of the diodes needed and secondly are they voltage specific ie only work on a positive feed . Thanks in advance and can anyone recommend a supplier (i have seen blocking diodes for small solar panels etc but i have no idea if they would cover my 2 x 30watt lamps) - Mark

 

[rtbcomp]

I'd check the legalities first, I think 2x30 watts will be a bit high for DRLs and I think front fogs have to come on with dip beam, I'm open to correction though.

That said do you want them to come on when the ignition is on and then via the normal switch when the sidelights are on?

If so you can do it with one changeover relay and one blocking diode, the diode will only have to handle the relay current, so doesn't need to be that big, 1 Amp would be more than adequate.

 

[Julian_P]

It's illegal to run front (and rear) fog lights in conditions of clear visibility. Front fogs sit low down on the vehicle in order to penetrate through the fog but the downside to this is that the beam adjustment is practically horizontal thus any movement of the vehicle over uneven surfaces is more likely to dazzle oncoming motorists. That's the trade-off with front fogs and as such leaving them on will probably reduce safety contrary to your wishes.

I sometimes think people want them on as they suspect they look cewl!

''it is illegal to use your fog lights in normal conditions.
Some drivers think that the lights on the front of their cars are spot lights, on most cars they are fog lights, you need to check your drivers hand book.
If you do use them, and are stopped by the police it would be a case of you driving without due care and attention. or having no consideration for other road users.''

Julian

 

[rikrobson]

If you want lights on during the day turn on your headlights or buy a Volvo. I've Got a V40 and you just cant turn them off. In normal bright daylight there should not be a need for lights in this country. Scandinavia has dark winters and 24 daylight in the summer. If the road conditions get too dark then you simply need to turn on your headlamps.

Fog lamps are over used and are for fog i.e less than 100m visibility, and not daylight driving.


these are the highway code rules, that are based on the relevent laws.

Rule 114: You MUST NOT

use any lights in a way which would dazzle or cause discomfort to other road users, including pedestrians, cyclists and horse riders
use front or rear fog lights unless visibility is seriously reduced. You MUST switch them off when visibility improves to avoid dazzling other road users (see Rule 226).

In stationary queues of traffic, drivers should apply the parking brake and, once the following traffic has stopped, take their foot off the footbrake to deactivate the vehicle brake lights. This will minimise glare to road users behind until the traffic moves again.
Law RVLR reg 27

Rule 226: You MUST use headlights when visibility is seriously reduced, generally when you cannot see for more than 100 metres (328 feet). You may also use front or rear fog lights but you MUST switch them off when visibility improves (see Rule 236). Law RVLR regs 25 & 27

Rule 236: You MUST NOT use front or rear fog lights unless visibility is seriously reduced (see Rule 226) as they dazzle other road users and can obscure your brake lights. You MUST switch them off when visibility improves.



and here is the LAW
The Road Vehicles Lighting Regulations 1989

Requirements about the use of headlamps and front fog lamps25.—(1) Save as provided in paragraph (2), no person shall use, or cause or permit to be used, on a road a vehicle which is fitted with obligatory dipped-beam headlamps unless every such lamp is kept lit–
(a)during the hours of darkness, except on a road which is a restricted road for the purposes of section 81 of the Road Traffic Regulation Act 1984 by virtue of a system of street lighting when it is lit; and
(b)in seriously reduced visibility.
(2) The provisions of paragraph (1) do not apply–
(a)in the case of a motor vehicle fitted with one obligatory dipped-beam headlamp or a solo motor bicycle or motor bicycle combination fitted with a pair of obligatory dipped-beam headlamps, if a main-beam headlamp or a front fog lamp is kept lit;
(b)in the case of a motor vehicle, other than a solo motor bicycle or motor bicycle combination, fitted with a pair of obligatory dipped-beam headlamps, if–
(i)a pair of main-beam headlamps is kept lit; or
(ii)in seriously reduced visibility, a pair of front fog lamps which is so fitted that the outermost part of the illuminated area of each lamp in the pair is not more than 400 mm from the outer edge of the vehicle is kept lit;
(c)to a vehicle being drawn by another vehicle;
(d)to a vehicle while being used to propel a snow plough; or
(e)to a vehicle which is parked.
(3) For the purposes of this regulation a headlamp shall not be regarded as lit if its intensity is reduced by a dim-dip device.


sec 27
2Front fog lamp
Prohibited uses:
(a)Used so as to cause undue dazzle or discomfort to other persons using the road.
(b)Used so as to be lit at any time other than in conditions of seriously reduced visibility.
(c)Used so as to be lit when a vehicle is parked.

 

[drivewasher]

Also fog lamps are designated by height from the floor IIRC it's 550mm. That is below 550mm they are fog light and above 550mm they are driving or spot lights

 

[Shox Dr]

It's not that fog lights are illegal it's the height from the floor.

Doh, Drivewasher got there before me.

 

[Wedg1e]

these are the highway code rules, that are based on the relevent laws.

Rule 114: You MUST NOT

use any lights in a way which would dazzle or cause discomfort to other road users, including pedestrians, cyclists and horse riders
use front or rear fog lights unless visibility is seriously reduced. You MUST switch them off when visibility improves to avoid dazzling other road users (see Rule 226).

In stationary queues of traffic, drivers should apply the parking brake and, once the following traffic has stopped, take their foot off the footbrake to deactivate the vehicle brake lights. This will minimise glare to road users behind until the traffic moves again.
Law RVLR reg 27

Rule 226: You MUST use headlights when visibility is seriously reduced, generally when you cannot see for more than 100 metres (328 feet). You may also use front or rear fog lights but you MUST switch them off when visibility improves (see Rule 236). Law RVLR regs 25 & 27

Rule 236: You MUST NOT use front or rear fog lights unless visibility is seriously reduced (see Rule 226) as they dazzle other road users and can obscure your brake lights. You MUST switch them off when visibility improves.



and here is the LAW
The Road Vehicles Lighting Regulations 1989

Requirements about the use of headlamps and front fog lamps25.—(1) Save as provided in paragraph (2), no person shall use, or cause or permit to be used, on a road a vehicle which is fitted with obligatory dipped-beam headlamps unless every such lamp is kept lit–
(a)during the hours of darkness, except on a road which is a restricted road for the purposes of section 81 of the Road Traffic Regulation Act 1984 by virtue of a system of street lighting when it is lit; and
(b)in seriously reduced visibility.
(2) The provisions of paragraph (1) do not apply–
(a)in the case of a motor vehicle fitted with one obligatory dipped-beam headlamp or a solo motor bicycle or motor bicycle combination fitted with a pair of obligatory dipped-beam headlamps, if a main-beam headlamp or a front fog lamp is kept lit;
(b)in the case of a motor vehicle, other than a solo motor bicycle or motor bicycle combination, fitted with a pair of obligatory dipped-beam headlamps, if–
(i)a pair of main-beam headlamps is kept lit; or
(ii)in seriously reduced visibility, a pair of front fog lamps which is so fitted that the outermost part of the illuminated area of each lamp in the pair is not more than 400 mm from the outer edge of the vehicle is kept lit;
(c)to a vehicle being drawn by another vehicle;
(d)to a vehicle while being used to propel a snow plough; or
(e)to a vehicle which is parked.
(3) For the purposes of this regulation a headlamp shall not be regarded as lit if its intensity is reduced by a dim-dip device.


sec 27
2Front fog lamp
Prohibited uses:
(a)Used so as to cause undue dazzle or discomfort to other persons using the road.
(b)Used so as to be lit at any time other than in conditions of seriously reduced visibility.
(c)Used so as to be lit when a vehicle is parked.

Oh if only this was more strictly policed...

The remark about people 'looking cool' is spot-on. Ford even modified the old TV ad for the Mondeo as it stated 'sporty front foglights'... meaning what? It's OK to drive 'sportily' in fog?

 

[voipio]

I find DRLs are the single most distracting thing on the road these days. After months of trying to overcome the desire, I still find myself looking at the daytime running lights and not the car they're on. Psychologically they become dissociated from the vehicle they're on. They are just lights, not a car coming towards me!! That to me is wrong as my attention is being taken away from more important things! DRLs have been banned in several EU countries because the accident rate increased when they were introduced. A report commissioned by the DFT found the claimed safety benefits to be tenuous, at best. LEDs are worse than filament bulbs and I found DRLs less troublesome when I forgot my glasses (without them, my vision is still good enough [just] to pass the driving test, and 20/20 with them on) so it seems that it might be the sharpness (and therefore intensity) of the image formed on the retina that's the problem. Those LEDs are awfully bright sources, and the sharp images formed in the eyes of someone with 20/20 vision will be also be bright, and will suppress the retinal cells carrying image information from adjacent parts of the retina. Effectively partially blinding oncoming drivers. See page 516 of the following reference for an explanation of why this happens:
http://hebb.mit.edu/courses/connectomics/Kandel-Chapter26-Retina_OCR.pdf

 

[Julian_P]

I've Got a V40 and you just cant turn them off. .

Not that I really know what I'm talking about so this could be bull, but if you find someone with a laptop with 'Volvocom' (or whatever Volvo call it) on you should be able to re-programme the relevant module in the car in order to stop this. It's all this CAN bus stuff these days......

A Volvo forum should help you maybe?

Julian

 

[julianthegypsy]

Led's are also monochroic, all the light at the same frequency which is not good for the eyes if looked at directly...

 

[AndyStobbs]

I find DRLs are the single most distracting thing on the road these days. After months of trying to overcome the desire, I still find myself looking at the daytime running lights and not the car they're on. Psychologically they become dissociated from the vehicle they're on. They are just lights, not a car coming towards me!! That to me is wrong as my attention is being taken away from more important things! DRLs have been banned in several EU countries because the accident rate increased when they were introduced. A report commissioned by the DFT found the claimed safety benefits to be tenuous, at best. LEDs are worse than filament bulbs and I found DRLs less troublesome when I forgot my glasses (without them, my vision is still good enough [just] to pass the driving test, and 20/20 with them on) so it seems that it might be the sharpness (and therefore intensity) of the image formed on the retina that's the problem. Those LEDs are awfully bright sources, and the sharp images formed in the eyes of someone with 20/20 vision will be also be bright, and will suppress the retinal cells carrying image information from adjacent parts of the retina. Effectively partially blinding oncoming drivers. See page 516 of the following reference for an explanation of why this happens:
http://hebb.mit.edu/courses/connectomics/Kandel-Chapter26-Retina_OCR.pdf

Frankly if you're having difficulties differentiating between a light and a car, be it mental or visual, you shouldn't be on a road.
I agree DRLs are pointless, and can well believe they do little, if anything to improve safety. They are now a requirment for all newly homologated cars, so for the time being they're here to stay.

 

[Wallace]

Not that I really know what I'm talking about so this could be bull, but if you find someone with a laptop with 'Volvocom' (or whatever Volvo call it) on you should be able to re-programme the relevant module in the car in order to stop this. It's all this CAN bus stuff these days......

A Volvo forum should help you maybe?

Julian

I'm sure it's in the handbook, I seem to remember our V40 came with them on and I turned them off using a combination of switches. If I remember tomorrow I dig the book out.

 

[MattF]

Led's are also monochroic, all the light at the same frequency which is not good for the eyes if looked at directly...

No idea on the specifics of what it is, but whatever the lighting used on modern vehicles and these new after market lamps, they're hateful things when ones eyes tend to be light sensitive at the best of times. It's like being stuck in the eye with a needle with that crap they're putting in headlamps these days.

 

[normspanners]

The volvo ones are a Pita you have to put the side lights on to switch the drls off, then you forget and flatten the battery. But I do understand the effect of the lights on your eyes I tend to have the same effect from the cars that have the lights up the rear pillars by the roof like the older ford Focuses, they have no low down reflectors and when on the motorway seem to me to get lost in the lights of the cars up ahead of them. but I remember being at the local hgv testing station and they failed a brand new well first test bin lorry that was in front of me coz its rear light units were too high yet they did not appear to be as high as a focus ones. But they did try to fail me coz my skip trailer didnt have height marker (outline) lights, but to sticking to the regs they could be under the side lights !! they just had to be 100mm away HOW RIDICULOUS .

 

[rikrobson]

with the v40 they are on with the switch off and on with the switch on. You can turn the side lights on with the swithc on sidle lights but then they stay on. just leavre them on the on position now. tho onlt difference i can find is the main beam doea not stay on withthe light switch off.

really anoying. but its an old v40. only cost me £250

I can live with lights on for that

 

[Tin Can]

Sorry - Big Sorry - I forgot to add that i would be replacing the the 27watt halogen bulbs with compatible lower brightness LED bulbs i have managed to find available for such conversions. My aim is not to look cool just to be more visible. As part of new vehicle type approval DRL's will have to be fiited to vehicles type approved from 2012 so it sounds as if they must be of benefit for this new regulation to be introduced - Mark

 

[rtbcomp]

Thanks for clearing that up, you said "i have seen blocking diodes for small solar panels etc but i have no idea if they would cover my 2 x 30watt lamps" which caused some confusion.

So all you need to do now is wire them up to the ignition circuit, the foglamp circuit would be redundant.

Again I would check the regs regarding lamp placement.

 

[Wallace]

with the v40 they are on with the switch off and on with the switch on. You can turn the side lights on with the swithc on sidle lights but then they stay on. Just leavre them on the on position now. Tho onlt difference i can find is the main beam doea not stay on withthe light switch off.

Really anoying. But its an old v40. Only cost me £250

i can live with lights on for that

From our S40/V40 owners manual.........

 

[Julian_P]

So all you need to do now is wire them up to the ignition circuit, the foglamp circuit would be redundant.

Again I would check the regs regarding lamp placement.

And there I suspect will be another illegality as vehicles of a certain age if fitted with fog lights as standard fitments must have them fitted and functioning correctly in accordance with legislation. Certainly an MOT fail.

Substitution of the correct bulbs with some little LED fairly lights is not satisfactory. (I would think)

Julian.

 

[Julian_P]

Frankly if you're having difficulties differentiating between a light and a car, be it mental or visual, you shouldn't be on a road.
.

I think you're being a little unkind here. I can understand the OP's point as I too tend to find this effect. As part of my job I have to visit a specialist doctor on an annual basis for a thorough medical examination and apart from needing reading specs my eyesight is very good.

Julian