Ford Focus Headlight bulbs

reeac

I haven't had a bulb blow for at least 20 years ...I agree with the suggestion to check the battery voltage with the engine running. Max.around 14.5 volts.

BeenThroughItAll

Check the headlamp units themselves are secure, loose units flapping about can vibrate bulbs to premature failure.

IamNotAllowedToUseMyName

The other problem with bulbs going is that when one goes it may put extra load on the remaining bulb (have you ever noticed how dazzling a single headlight can be when the other is blown). So if you don't deal with a blown bulb promptly you may well shorten the life of the other.

tedted

IanMSpencer wrote: »

The other problem with bulbs going is that when one goes it may put extra load on the remaining bulb (have you ever noticed how dazzling a single headlight can be when the other is blown). So if you don't deal with a blown bulb promptly you may well shorten the life of the other.

rubbish where do you get from

ohreally

IanMSpencer wrote: »

The other problem with bulbs going is that when one goes it may put extra load on the remaining bulb

Given they will (almost certainly) be on separate circuits, how does that apply?

buglawton

I once bought some cheapo headlight bulbs from Poundand, thinking they were all the same. They lasted a week and when they went, left the bulb glass deformed which is unusual.

IamNotAllowedToUseMyName

tedted wrote: »

rubbish where do you get from

Simply because I've been dazzled by enough cars with faulty headlights to assume that whatever the circuit design is, that the failure of one does affect the voltage of the other.

Joe_Horner

ohreally wrote: »

Given they will (almost certainly) be on separate circuits, how does that apply?

They quite often share an earth point.

If that's less then perfect (which it usually is) then it'll drop volts according to the total current flowing and one blowing will reduce the current, so reducing the voltage loss that the other bulb sees.

But the effect is only to return the working one closer to "correct" voltage - it may appear to brighten but it's only returning to it's normal output.

System

n217970 wrote: »

6 bulbs in 2 years? Thats hardly "eating" and doesn't suggest a problem -

Yeah actually it does. I work nights with a 30 mile each way commute. I've had my Mondeo 6 years, done over 85k in it, most of that at night, and I've only replaced each headlamp bulb twice.

Cheap bulbs will go in no time and they're a false economy because you'll pay more in replacements over a couple of years than you would have done just buying a decent one which lasts far longer. Tell your son to go to their local Ford dealer and get the cheap ones from there which I believe are Lucas so a decent brand and they'll be genuine Lucas too. Off the top of my head I think they're £5 a bulb.

System

IanMSpencer wrote: »

The other problem with bulbs going is that when one goes it may put extra load on the remaining bulb (have you ever noticed how dazzling a single headlight can be when the other is blown).

Can never ever ever happen without a monumental change in the laws of physics. A single light looks brighter because there's not another one on the oncoming car to compare it to. Its in your head.