Xantia full beam headlights not working

[daviemck2006]

It's not the car but in my house the centre ceiling lamp has 4 x 50W halogen bulbs. It was forever blowing bulbs. Since fitting a dimmer switch to it I haven't blown a bulb in 18 months. I always reduce the brightness before switching off so they are never off to full on.

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[Stickyfinger]

OK another thicko question: will a supply/earth that has a fluctuating resistance shorten the life of a bulb ?

[daviemck2006]

OK another thicko question: will a supply/earth that has a fluctuating resistance shorten the life of a bulb ?

I don't know the answer to that so I must be a thicko too lol

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[CitroJim]

OK another thicko question: will a supply/earth that has a fluctuating resistance shorten the life of a bulb ?

I wouldn't imagine so...

It will just make it flicker and if the resistance is significant for the majority of the time it may even extend its life a little...

[Stickyfinger]

Maybe then a result of low/poor power supply/ bad earths/ old "green" wires ?

[myglaren]

I thought I had a chart for Voltage vs. longevity but it wasn't.
Instead it is of brightness at increasing voltages - this is for halogen headlights.

10.5V : 510 lumens
11.0V : 597 lumens
11.5V : 695 lumens
12.0V : 803 lumens
12.5V : 923 lumens
12.8V : 1000 lumens 
13.0V : 1054 lumens
13.5V : 1198 lumens
14.0V : 1356 lumens 
14.5V : 1528 lumens

[CitroJim]

That chart shows why the S1 Xantia headlight relay modification is so effective Steve...

The difference in output with just a small voltage reduction is really quite staggering!