Electrical: LED replacement bulbs - general discussion

[Jungle_Jim]

Hi all
This topic has come up on another thread but deserves its own discussion...

Replacement automotive LED bulbs have been on the market for a few years. They are more expensive, but very efficient and long lasting. But unfortunately it turns out that fitting LEDs to most cars is illegal, unless the car came with them new.

Here's an article about it...
https://www.motoringassist.com/motor...ght-bulbs-car/

It seems that insurance companies might try to use them as an excuse to void policies.

I was in Halfords recently, looking at their range of LED lights, and each one has smallprint on the back... 'offroad use only'.

The only LEDs you can use legally are interior lights - no exterior or road lights including numberplate lights.

The other problem which can happen with LEDs is that the bulb failure warning light will come on, because LEDs will show very different current draw/resistance characteristics to the old bulb, so the sensor will think that the bulb has blown. I don't know how to fool the bulb failure sensor - it might involve putting a resistor in series or something.

It's a shame they're illegal, because they use around 20% of the power of normal bulbs and last much longer. I bought a tail-light pair last year, before I realised they were illegal, and they worked well, though I never rectified the bulb failure light. But I continue to use LED interior lights - having replaced 5w bulbs with 4w LED bulbs which throw out the same light as a normal 20w - much easier to read a map.

Any thoughts or experiences with LED bulbs?

John

[hennabm]

I have fitted my no plate lamps with LEDs. This is purely because of the bangs they get when the tailgate gets slammed down.

Seem to be fine to me.

[Nicholas Lewin]

Hi John

Ooops! I wasn't aware they were illegal... I tried fitting Halfords LED indicator bulbs earlier this summer. Brighter and quicker yes, but the bulb failure sensor came on immediately and as one of the bulbs broke when I installed it I simply took the whole lot back to Halfords for a refund...

Salutory lesson and the car is running on conventional bulbs

Thanks for the legality warning however

Nick

[SwissXC90]

Originally Posted by Jungle_Jim

The other problem which can happen with LEDs is that the bulb failure warning light will come on, because LEDs will show very different current draw/resistance characteristics to the old bulb, so the sensor will think that the bulb has blown. I don't know how to fool the bulb failure sensor - it might involve putting a resistor in series or something.

It's a shame they're illegal, because they use around 20% of the power of normal bulbs and last much longer.

Yes they use 20% of the power BUT to avoid the bulb warning light you need a resistor to consume the remaining 80% of the power

So you don't save any power at all, you just convert the power to 20% light, 80% heat, which is around the same as the bulb you replaced.

End result: no gain other than
a) different lamp output color, and
b) potentially longer life - but that depends on the quality of the LED bulb

In addition to the above, the LED does not emit light at the same focal point of the tungsten filament, meaning the beam pattern for the light is not the same.
This is exactly why they are not allowed in some areas. Because the beam pattern changes

[rtbcomp]

Originally Posted by Nicholas Lewin

Hi John

Ooops! I wasn't aware they were illegal... I tried fitting Halfords LED indicator bulbs earlier this summer. Brighter and quicker yes, but the bulb failure sensor came on immediately and as one of the bulbs broke when I installed it I simply took the whole lot back to Halfords for a refund...

Salutory lesson and the car is running on conventional bulbs

Thanks for the legality warning however

Nick

What car was that on? According to the wiring diagrams the indicators don't go through the bulb warning relay on the 200 series, you rely on the increased frequency of the indicator unit to warn of a blown indicator bulb.

[SwissXC90]

I was browsing the Osram LED documentation last night

None of the LED lamps are approved for use as exterior lights.

They are only approved for use as interior lamps

[baggy798]

I use a few:

Reverse lights - 1156 ba15s 27 SMD 5050 Warm White LED
3 years no issues.

Number plate lights - T10 501 W5W 5 SMD 5050 Warm White LED
They last about a year before they start flickering and dying.

Front sidelights - 1156 ba15s P21W 5050 8 SMD Warm White LED
3 years no issues, slightly brighter than the originals making the car more visible.

For the indicators I used the same ba15s 27 SMD 5050 LED warm white bulbs as the reverse lights:



The side repeaters use the same 5w bulb as the door edge markers and the rear number plate, so I used some more T10 (501) W5W 5 SMD 5050 warm white bulbs:



The 5 plastic bits sticking out have to be cut off, as the plastic socket housing on the LED bulb is a little wider than a traditional bulb.



To stop the lights flashing too fast, the indicator relay needs to be replaced with a type that is LED compatible. Replacing the relay also means you don't have to hack around the wiring and splice in load resistors for each bulb.

LED compatible flasher indicator relay works with mixed LED / Bulb combinations



I later upgraded the main indicator bulbs to '33 SMD 5630 LED' bulbs as they are slightly brighter. No issues with anything after 3 years.

Not bothered about whether they are legal or not, they pass the MOT so it's all good.

[SwissXC90]

Originally Posted by baggy798

Number plate lights - T10 501 W5W 5 SMD 5050 Warm White LED
They last about a year before they start flickering and dying.

Interesting
So the lifespan of cheap LED lights is less than than of the good old fashioned filament light bulbs....

[baggy798]

It's a really crappy moist environment so it's to be expected really. Those bulbs are from the same batch that I use in the instrument cluster, door edge markers (1x replaced), and side repeaters.

All the bulbs I use are China's finest. UK sellers use the same bulbs with usually a 1000% markup.

[Jungle_Jim]

So this sounds like a significant weakness of LED lights...

They are vulnerable to moisture. Normally there is some exposed soldered circuit-board type material in a LED bulb, which would last a while with humidity, but eventually corrosion would settle in.

I don't know if there's is a moisture barrier you could put on an LED - the trouble is that they get hot, and need ventilation.

Good old filament bulbs - at least they are sealed, and it's only the connectors to worry about regarding damp/corrosion.

John