Headlight Bulbs blowing, charging at 16volts!

[Kevin Bacon 5]

It's a funny one! Not sure why it happens to be honest. We had a spate of bulbs blowing on our 06 Polo but it cleared up and hasn't done it since. I put that down to a bad batch of bulbs :shrug: Put a cheapy Halfords basics range one in and it's been fine since!

 

Most car electrics, ECUs especially, are designed to operate over a wide voltage range, usually 8-16V. Obviously they'll perform best around 14V but I suspect DC filament bulbs aren't too happy with a rough alternator output (sine wave). Your Alt may be showing the right voltage but it might not be smooth.

 

You can try a new diode pack in your Alt. They're only around £15 - http://cgi.ebay.co.uk/ALTERNATOR-REGULA ... 35ae210bcd

 

Other than the regulator, the only other thing that wears out inside an Alt are the bearings and what they call 'slip rings', which are the copper contacts the regulator brushes rub on. Only costs about £60+VAT to fully overhaul a VR6 Alt at a local auto sparkies :D

 

The only other thing I can suggest is checking your earths and good and clean etc and perhaps try a different brand of bulb. Just cheapo ones until the issue is sorted!

[jamiehamy 0]

Thanks Kev.

 

I know this might sound daft, but what earth should I be checking? I've tried to find one relating directly to the headlamps but to no avail. The battery earth connection is clean enough.

 

I'll rewire the loom tonight and see how it goes...

[andy 0]

I'd try some more bulbs too mate. 3 blowing especially when 1 was a cheapy might be a coincidence. You've done the right thing checking the alternator output.

[Kevin Bacon 5]

Sorry, I meant check the earth you used for the uprated headlight loom.

 

There's a grouped earth point in the chassis leg behind the battery. Personally I would earth all accessories to that point.

[jamiehamy 0]

Just thought I'd clsoe my issue off for now. Replugged the loom with some average quality bulbs - not had an issue and that's over a month. Only thing I'm thinking is that on occasion I've held the stalk so the main and dipped are on at once and possibly the heat has blown the filament. Probably will never know, but so far so good.

 

Thanks to Andy and Kev :)

 

I'd try some more bulbs too mate. 3 blowing especially when 1 was a cheapy might be a coincidence. You've done the right thing checking the alternator output.