DRL- Daytime Running Light working

DRL- Daytime Running Light working

What is a daytime running light

A daytime running light (DRL) is a forward lighting device that is intended to increase the visibility of a vehicle to other road users during daylight hours. The purpose of using daytime running lights is to reduce crashes by increasing the visual contrast between a vehicle and its background at times when headlights are not typically activated. The crash reduction potential of these lights is a function of their ability to attract attention with a sufficient level of luminance which improves the noticeability and detectability of vehicles in the central and peripheral fields of view. Improved vehicle visibility allows other road users to initiate evasive action in sufficient perception-reaction time and distance.

Various configurations of DRLs have been implemented: highbeam headlights at reduced intensity, low-beam headlights at full or reduced power, front turn signal lights (steady burning until the turn signal control is activated), and dedicated lights with a defined luminous intensity and beam pattern.

How Do You Use Daytime Running Lights?

There’s not much of a learning curve needed here. DRLs operate all on their own. They illuminate when you engage the ignition and extinguish when the headlights activate. The driver has no real control over operating DRLs because there is no DRL on-off switch.

Implementations

An increasing number of vehicles are equipped with dedicated DRLs for enhanced road safety and compliance with the mandatory DRL requirements in some countries. As compared to fog lamps which direct light down towards the road surface, dedicated DRLs typically direct light forward without a sharp cutoff at the top. A substantial amount of light may be directed above the horizon to make the vehicle more conspicuous to other road users. Luminous intensity is the key DRL parameter and the required candela level varies in different countries. Dedicated DRLs typically produce an output of similar intensity to low-beam headlamps or emit in a lower intensity.

Daytime running lights are activated automatically when the engine starts. They operate continuously during the time when the headlights are not in use or the headlight is being used as a flasher signal. Dedicated DRLs are installed in pairs and must be positioned so that each light is not more than 400mm from the extreme outer edge of the vehicle. The center of each light should be at least 600mm away from the center of the other light.

Lighting technology

LED technology is the most logical choice for the development of daytime running lights. The wide acceptance of LEDs is due to their high energy efficiency, long service life, durability against vibration, as well as excellent controllability in light distribution, intensity effectiveness and spectral power distribution (SPD). LED daytime running lights can take various forms such as light bars, flexible strips, daisy chain modules, ellipsoidal and round lights. The small size of LEDs enables more freedom in creating form factors for seamless integration with the vehicle exteriors. Dedicated DRLs are self-contained luminaires sealed to an ingress protection rating of IP67 or above. They operate on 12V or 24V electrical systems.

Environmental impact

LED daytime running lights

DRL power consumption varies widely depending on the implementation. Current production DRL systems consume from 5watts (dedicated LED system) to over 200 W (headlamps and all parking, tail, and marker lights on). International regulators, primarily in Europe, are working to balance the potential safety benefit offered by DRL with the increased fuel consumption due to their use. Because the power to run the DRLs must be produced by the engine, which in turn requires burning additional fuel, high-power DRL systems increase CO2 emissions sufficiently to affect a country's compliance with the Kyoto protocol on greenhouse gas emissions.[10] For that reason, low-power solutions are being encouraged and headlamp-based systems are not allowed after DRLs became mandatory in Europe at the beginning of 2011. LEDs and low-power, high-efficacy, long-life light bulbs produce appropriate amounts of light for an effective DRL without significantly increasing fuel consumption or emissions. Fuel consumption reductions of up to 0.5 mpg may be found when comparing a 55 W DRL system to a 200 W DRL system.[12] In 2006, the UK's Department of Transport also found significant reductions in emissions and fuel consumption when comparing a 42 W DRL system to a 160 W full headlight DRL systems.[13] DRL fuel consumption can be reduced to insignificant levels by the use of 8 to 20 W DRL systems based on LEDs or high-efficacy filament bulbs.

Driver circuit design

LEDs are current-driven devices that are sensitive to changes in operating conditions, such as voltage and temperature. It is necessary to equip the lights with a driver circuit that provides tight regulation and control on the current output provided to the LED load. A DC-DC converter that employs switching regulation can be designed to compensate for voltage fluctuations and operate over a wide voltage range (e.g., 9 to 33 volts). However, switching circuits produce electromagnetic interference (EMI) that that has to be suppressed by careful circuit board design, screening, and filtering. Linear regulators do not produce EMI emissions but have the limitation of having to ensure that the LED forward voltage is lower than the battery voltage.

PROS & CONS OF DRL

PROS

Pros

Statistical Evidence – Despite the government’s stand that there isn’t enough evidence to warrant mandating DRLs, there is some evidence. A 2010 publication from the Minnesota Department of Transportation stated that DRLs reduced the number of daytime crashes from 5% to 10%. A 2008 study from the National Highway Traffic Safety Administration (NHTSA) placed the accident reduction with DRLs at 5.7% for light trucks and vans.

Dim Ambient Light – When there is enough light that you don’t require headlights, but the light is fading, DRLs are at least somewhat effective. They can increase the likelihood of seeing an approaching vehicle, particularly a dark-colored one.

Insurance Discounts – Some insurance companies may provide discounts to drivers with vehicles using DRLs. Such discounts may vary by state.

They Look Cool – There’s no doubt about it: Today’s crop of DRLs adds some spark to the face of cars, trucks, and SUVs by making vehicles look more technologically advanced.

Cons

• Driver Confusion – The most common complaint about DRLs is that they throw out enough illumination to fool some drivers into thinking their headlights are on when they aren’t. Although approaching drivers will still see you, and you will see them, DRLs don’t do much to illuminate the road. Moreover, if your headlights aren’t engaged, neither are your taillights, creating a major safety hazard in the dark.

• Additional Fuel Consumption – Believe it or not, DRLs add to the load on the alternator, requiring burning more fuel to keep up with the power demands. This also means a bit more stress on the alternator. However, the additional gas and extra stress on the alternator are minimal and hardly worth discussing. Besides, most DRLs on today’s new cars are LEDs, requiring very little energy. Heated seats and heated steering wheels also sap power from the alternator, requiring burning extra fuel.

• They Draw Away Attention from Other Things – Most motorcyclists operate their vehicles with the headlight illuminated no matter the time of day. They do this with the belief it makes them more visible to other traffic. Many of these same motorcyclists argue that the proliferation of DRLs distracts from motorcycles’ headlights, reducing their safety. Some anti-DRL advocates contend that all DRLs attract too much of other drivers’ attention making it less likely they will notice pedestrians, bicyclists, and other objects on the road.

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