Author Topic: Head lights on Passat are useless  (Read 1904 times)

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Offline B5Passat

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Head lights on Passat are useless
« on: June 14, 2021, 09:48:29 pm »
On my 2012 Passat my head lights on are useless. I can barely see anything at night. I definitely miss having xenon lights that my other Passats had. What options are there to upgrade them either with new headlights or bulbs etc?

Offline johnp

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Re: Head lights on Passat are useless
« Reply #1 on: June 18, 2021, 01:49:25 pm »
check the voltage at the headlight bulb  itself.
The lights should not be useless.

Offline tandy

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Re: Head lights on Passat are useless
« Reply #2 on: June 19, 2021, 11:43:58 am »
On my 2012 Passat my head lights on are useless. I can barely see anything at night. I definitely miss having xenon lights that my other Passats had. What options are there to upgrade them either with new headlights or bulbs etc?

We have just picked up a 2011 b7 wagon and have the same issue with the lights being pretty crap - i thought it may have been the self leveling out of adjustment as the beam seems to be not projecting forwards/upwards as much as it should.  Is the low voltage at the bulb a common issue??

Offline B5Passat

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Re: Head lights on Passat are useless
« Reply #3 on: June 19, 2021, 07:36:21 pm »
In the end I decided to get Philips RacingVision GT200 halogen range bulbs.

Offline Gordo

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Re: Head lights on Passat are useless
« Reply #4 on: June 20, 2021, 12:34:42 am »
Many modern vehicles have woefully undersize wiring - with incandescent (including halogen) filaments the power is proportional to the square of the voltage, and the actual light output to the third power (IIRC).
What this means is a 10% voltage drop means it's getting 90 of the potential voltage, 81% of the power, and 73% of the light output. Worse, when comparing it to the alternator voltage (the highest voltage available), it can be 20%, or more, drop off. I have had vehicles where I've had 14.3V across the bulbs - VERY good output with four 100W 'high' beam bulbs and the two 80W dip' permanently on with the lights - with power taken directly from the alternator output, way oversized wiring and individual relays.

Normally, I'd suggest rewiring the headlights with heavier gauge wiring (including the earth) using individual relays. However, some vehicles may have issues with the 'light fail' warning, so this may need to be disabled/warning light removed.
These are my thoughts and opinions - sometimes I'm wrong, but not often ;-)