*Advice/Warning to fellow Audi A3 8P3 owners with 100w bulbs*

[dany2k]

Hi all,
I've just been stung pretty badly just the day before selling my car: these words of warning are for my fellow forum members whose words of advice have saved me previously!

I've been using 100w bulbs/LED sidelights for around 18 months with no issue (or so I thought). In that that time the sidelights have blown on two occasions (different sides) and the headlights on two occasions also. I'm very conscientious when installing bulbs and ensure I leave nothing to chance.

A sidelight went again (the third time in total). Upon changing it and the new LED not working, the car went straight to my trust independent(the rear passenger LED tail-light stopped working, as well as the opposite side headlight). It transpired that my onboard supply control unit had "melted" (part number 8P0 907 279 N) - leaving me to order the part from TPS for £319 including VAT!

I cannot say for sure that the bulbs are linked to this disaster, but this is simply a word of warning for fellow 8P3 owners.

Hope it saves somebody else the pain!

Dan

 

[ItsAllGood]

Those headlights are not supposed to be runned with 100w bulbs, isn't the recommended/standard 55w?

 

[desertstorm]

It will be the bulbs that have caused the problem. A normal 55w takes around 4.5A current, a 100W bulb around 7.5A .
The amount of heat created in a circuit is related the current squared. so 4.5 * 4.5 = 20.25 . and 7.5 * 7.5 = 56.25 so although the extra current is around 1.6 times more the effect of the heating is 2.8 times that of the normal current.
The on board units use a low value burden resistor to monitor the bulb current so they can tell when the bulb fails, the resistor is designed to withstand the normal bulb current. But will get very hot with the higher current bulb.
It's good of you to post this to warn other people. it's not just modern cars that suffer with this issue, I used to have a 1984 Astra 1.6 SR that I fitted 100W bulbs too and that fried the switchgear and I ended up driving home on sidelights.

Ever since just used uprated standard bulbs in cars Osram Nightbreakers are pretty good, The Unlimited ones are 110% more light than a standard bulb.

Karl.

 

[downtothebone]

Isnt this kinda of common sense - standard bulbs are rated at 55w for a reason ... why would anyone even think that running a 100w bulb in a circuit designed for 55w would not lead to problems.

 

[WOLF]

ive had 100w bulbs crazed my headlight lens on a bora I had so I stay clear

 

[dany2k]

Isnt this kinda of common sense - standard bulbs are rated at 55w for a reason ... why would anyone even think that running a 100w bulb in a circuit designed for 55w would not lead to problems.

Ordered the bulbs from forum member t8ups - didn't think it would be a problem if sold by a Sponsor Member without warning. Lack of "common sense" aside, my aim is to impart word of warning for others out there. Hope it saves somebody £300+!

Dan

 

[Newy]

Yeah cheers for good intentions .... Nice to keep the guys informed ... We live and learn

 

[s3_trev]

Did you let Trups know?

 

[hades-]

£319 inc
******* hell.

ebay or breakers

 

[dany2k]

Did you let Trups know?

I haven't as of yet, but certainly will do. Car is now sold, but I sincerely hope my experience helps somebody!