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Automotive Articles

D5S: The entry into premier league of car lighting


The first vehicles with 25-watt Xenon lighting have been on the road since 2013. Find out more about the new Xenon bulbs, what they can do and where they are used here.

 

In vehicles from the mid-range upwards, the new Xenon lights frequently replace the halogen bulbs that were previously used as standard, which significantly improves the lighting. For the small car and compact class vehicle range, where the standard Xenon 35-watt lighting has so far not been offered at all, or where there has been very little demand, the 25-watt version is an attractively priced optional extra.

 

Automatic headlight range control and headlight washer system?

 

The common perception is that automatic headlight range control and a headlight washer system are compulsory for cars with Xenon lights, but this is only partially correct. The international regulations set out by ECE R48 do not actually refer to the type of bulb, but rather to the light stream emitted by the light source of the dipped beam. If the light stream is greater than 2000 lumen, the car must be fitted with both automatic headlight range control and a headlight washer system.

 

This was a relatively simple matter in the past. Halogen bulbs were always below this limit and Xenon, with around 3200 lumen, were always above. This is what first created the reference to Xenon technology as it still appears in the StVZO (Straßenverkehrs-Zulassungs-Ordnung – German Road Traffic Licensing Regulations). The special feature of the 25-watt solution is that its light stream is now "only" 2000 lumen.

 

This means that the automatic headlight range control and headlight washer system can be omitted, although they can still be included. However, many car manufacturers are choosing to retain the automatic headlight range control and only dispense with the washer system. This maximises the benefit for the manufacturers, as only a small water tank is required, saving on space and weight.

 

Philips D5S with fully integrated electronics

Figure 1: Xenon D5S
Figure 1: Xenon D5S

The 25-watt solution from Philips is called D5S and integrates not only the starter—as with the D1 and D3—but also the complete ballast unit in the base. Additional electronics are no longer required. The D5S has an optimised light arc and is installed in a specially designed projection module.

 

The aim is to focus as much as possible of the available 2000 lumen onto the road, thus matching the road illumination achieved by the classic 35-watt Xenon as closely as possible.

 

D5S compared with D3S

 

According to the figures, the D5S with its 2000 lumen is closer to a H7 (1500 lumen) rather than to a standard Xenon bulb. The following comparison images from the Philips application laboratory show that this impression is deceptive.

 

The D5S bulb has an optimised, more compact light arc with a higher luminance. This is the measure for the brightness of the luminous "surface". Together with the specially adapted lens, the available light is utilised more effectively and is projected onto the carriageway more efficiently. The bulb also has a higher colour temperature of 4800 kelvin compared with the 4100 kelvin for a standard bulb.

Figure 2: D5S in the Citroën C4 Picasso 2013
Figure 2: D5S in the Citroën C4 Picasso 2013
Figure 3: H7 in the Audi Q5 2010
Figure 3: H7 in the Audi Q5 2010
Figure 4: D3S in the Audi A4 2010
Figure 4: D3S in the Audi A4 2010
The D5S is installed in the basic models of the new Audi A4, A6, Q3, Q7 and TT, the Maserati Ghibli and the Alfa Romeo 4C. It is available as an optional extra in the Vauxhall Corsa, Citroën C4 Picasso, Skoda Rapid, Alfa Romeo Gulia, Fiat 500X and the Jeep Renegade.

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