Dimming Headlights

Corby · February 2, 2004

Driving home tonight, I noticed that when i turned my heated rear screen on the dipped headlights dimmed quite considerably - and stayed dimmed (until I revved the engine). The revs were down at 750rpm - with heated screen on.

I know that the rear screen takes quite some power, but should it be that much? Should the Battery / alternator cope with it without showing any symtoms of reduced power??

Im worried that this maybe a sign that something is failing - or is it normal??

Any advice & comments greatly recieved.

Cheers.

Risky3301 · February 2, 2004

You haven't mention how old your car is or mileage

It could be the alternator not pushing out enough charge, you need to put a voltmeter across the Battery and rev the engine to 2000 to 2500 rpm, the voltage should be between 13.8 and 14.5 volts, if the reading is lower 13 volts, could be your alternator on it's way out.

Note

The volt meter in to 'IP' is only indication and should not be taken as being spot on.

Corby · February 2, 2004

The car is 51 reg, so late 2001 and done 32,000miles.

I know the voltmeter on the dash is approx 13.5 volts and not moving much with revs or load. I'll check with a voltmeter 2moro.

Would you expect an alternator to fail in just over 2 years? Would this be a warranty item?

Risky3301 · February 2, 2004

If the alternater is faulty then the dealer should renew it under warranty and yes I have known alternators to fail in a lot shorter period that 2 yrs and less that 32k

ColinBarber · February 2, 2004

I think you will find most do this. The alternator doesn't produce that much power at idle speed and the Battery isn't the best.

aido · February 2, 2004

Yes mine does this as well - just tried it as I got back tonight, idle with the heated rear screen on and the lights dim and the voltage meter shows ~12 - turn the heated screen off and it crawls back up to ~14.

Like Colin says nothing to worry about

Brettster · February 3, 2004

mine used to do this too

then my Battery went kaput and I got a 65amp Battery in now and it doesnt dim and that car seems a tad more responsive, that could just be in my head tho