LED lights, compatibility?

[Parrot of Doom]

One of my sidelights has gone, and I was thinking of replacing it with an LED bulb instead (both sides at once)

Any thoughts? Are they compatible with the Merc's 'defective bulb' warning system?

 

[Shude]

I considered this too but you'd need some load compensators or frankly a shedload of LEDs to fool the bulb warning system

 

[Parrot of Doom]

So I'd have to put a resistor in series with the bulb? Not a big deal, might be a nice little project for the afternoon.

 

[richard]

So I'd have to put a resistor in series with the bulb? Not a big deal, might be a nice little project for the afternoon.

In parallel, and big enough wattage to dissipate the extra current it uses without getting as hot as a bulb. The bulb failure warning system expects to see a 'bulb' taking the appropriate amount of current (i.e a 21 watt bulb takes about 21/12.5 amps)

Cheers
Richard

 

[Shude]

So I'd have to put a resistor in series with the bulb? Not a big deal, might be a nice little project for the afternoon.

Yes.

Like I said, I was considering this, but my plan was to put the resistors in a box somewhere in the engine bay, NOT next to the lamp itself to preserve wiring etc.

 

[Parrot of Doom]

Would probably have to be a wirewound resistor in a metal heatsink then

I wonder how much current those 6 LED bulb arrays draw, compared to your average bulb?

 

[richard]

Yes.

Like I said, I was considering this, but my plan was to put the resistors in a box somewhere in the engine bay, NOT next to the lamp itself to preserve wiring etc.

I suppose 'Parrot of Doom' could just put the original bulb under the bonnet somewhere !! I doubt the leds take much current at all ..

R

 

[Parrot of Doom]

Thats not a bad idea.....they could double up as underbonnet lighting....

 

[Shude]

I suppose 'Parrot of Doom' could just put the original bulb under the bonnet somewhere !! I doubt the leds take much current at all ..

You know actually that idea isn't as daft as it might sound

I could do with some footwell lighting in the front and rear...

 

[Bedouin]

One of my sidelights has gone, and I was thinking of replacing it with an LED bulb instead (both sides at once)

Any thoughts? Are they compatible with the Merc's 'defective bulb' warning system?

I'd have to ask - why bother? Filament bulbs are cheap and last for ages. The only real benefit of LEDs is their lower power consumption - but this is not usually an issue in a car

 

[Bedouin]

I wonder how much current those 6 LED bulb arrays draw, compared to your average bulb?

Typically the 12V LED set ups draw between 170mA and 350mA - about a fifth of that drawn by the filament bulb they replace

 

[RICHARD HILL]

simply connect a capacitor across the circuit 50 mf should do it.

 

[richard]

simply connect a capacitor across the circuit 50 mf should do it.

Richard - why is this ? Does the unit only check consumption as the lights are turned on - so the extra current draw from the capacitor charging is enough to trick the bulb failure software ?

Sounds like a nice, non heat generating, solution !

Richard

 

[Shude]

Richard - why is this ? Does the unit only check consumption as the lights are turned on - so the extra current draw from the capacitor charging is enough to trick the bulb failure software ?

If a bulb goes out during a journey the failure light comes on, also if you fix a faulty bulb (not all) while the engine is running the light goes out.

 

[RICHARD HILL]

The capacitor will use the extra ampere that is required to activate the light tell tale system but I cant see personally what benefit there is by using LED bulbs and having to do this. The idea when using these LED bulbs is to eliminate voltage draw and this is doing neither.

 

[MangoMan]

Surely by doing as suggested above, wouldn't it make the bulb failure warning system inoperable?

Personally I would prefer to know if a bulb was blown.

Just a thought...

 

[Parrot of Doom]

Well the main reason I was considering it was the colour of light emitted. The LEDs Im looking at are bright white, not yellow like filament lamps.

 

[Parrot of Doom]

I've ordered a couple of bulbs, when they arrive I'll fit them and let you know what happens, including some before/after piccies.

 

[Howard]

Got mine from here, not LED so no worries about the bulb warning system ....

http://www.autobulbsdirect.co.uk/home.php?cat=596

Colour is good, not the silly chavvy blue, but nice and white instead of the yellow i had before ....

The w124 takes the 233 t4w - i went for the Phillips Blue Vision - which belive me is not blue but nice white !!

I think the w210 will probably take the w5w capless - i would go Phillips Blue Vision again .. they really are very good !

 

[Jdukey]

I'm not convinced about the effectiveness of LED headlights, but certainly for tail lights / brake lights this would be a good idea. Because although the LEDs do break it is very rare indeed, and even when they do, only one at a time from the cluster, so the warning system becomes almost irrelevant.