On Wed, 15 Jan 2020 18:43:34 +0000, Jim GM4DHJ ... wrote:
The connector looks polarised and I'd be surprised if you could fit
them upside down. So without forcing one or the other I guess the new
bulbs are miss wired. Are they cheapy unknowns? Assuming only one
filament is bust compare continuity between old and new.
You would think that something as fundamental as wiring the base the right
way around might just be a little obvious before they sent them to anybody.
On the other hand maybe you car is upside down.
This newsgroup posting comes to you directly from...
Why didn’t you check the feedback before ordering?
BTW, it isn’t the wattage which determines the hi/lo beam. It is the
position of the light source/ geometry of the light assembly. Your eyes
almost certainly wouldn’t see the difference in intensity between a 55w and
60w bulb- they have a log response to intensity.
couldn't be bothered checking feedback 'till after the event...got a
reply this morning don't think they know anything about cars......"Hi,
sorry to hear that. How strange, I've not come across this before. Have
you tried putting them in the other way round please?
Sam"...........must be a wummin' .....the connector to the bulb only
goes on one way and the bulb only fits the headlight unit one way
.......yes in a reflector type headlight unit the dual filament bulb
like the H13 it is the position of the filament that gives the high low
beam so I was getting low beam when the high beam warning light is on
and vice versa ... .....anyway just put the original Philips bulbs back
in and all is fine....got another set coming from china so we will see
if they are OK.....only bought them as spares so thank god I checked
them out .....the filaments look the same in both sets of bulbs and are
positioned the same way so I can only assume the wiring from the pins to
the filaments is around the wrong way....unbelievable......not that you
ever believe anything I say ....
I'm surprised the supplier didn't try to sell you a plug-in "converter"
between the connector and the bulb, to correct the incorrect pin-to-filament
wiring in the bulb ;-)
How much tolerance is there in bulb position in a typical headlight, and how
much would it affect beam position? Many modern cars have very little
clearance between the rear of the reflector and engine mountings etc, so
fitting a bulb and securing it with the spring clip on the housing is
something that can only be done by feel rather than sight. I've often
wondered whether the bulb is properly seated, since I can't *see* whether it
is, and whether any mis-seating (eg if one of the location tabs on the bulb
is not flush with the housing) will affect beam alighnment.
I suppose the wiring error could have been worse: if they'd swapped the
common pin with another, you might have ended up with one dipped or beam
setting where the two filaments were in series and you got a very dim light
On 16/01/2020 09:30, Brian Reay wrote:
<snipped> > BTW, it isn’t the wattage which determines the hi/lo beam. It is the
In a headlight, the main beam filament is the same thickness as the dip
except that it's a little shorter, and this reduction in length hence
resistance accounts for the increased power.
The benefit of this is that the light is both brighter and whiter, the
downside is a shorter life, but of course main is used less than dip.
The relative lifetime is something like a twelfth power, so it's very
approximately something like a third of the lifetime.
There is a clear visible difference, not because of the extra power as
such, but because of the extra efficiency and 'whiteness'.
Like OHP lamps, overrun for increased brightness but shortened life,
hence why OHPs often have a spare bulb ready. Or would do if it had
And that's why old torch bulbs had odd voltages like 2.4V when using 3V
of battery - 2.4V corresponds to the IIRC 1000 hour life, but that's
traded for brightness and efficiency.
Indicator bulbs and brake lights are similarly overrun as their
operation is intermittent.
Illegal in the UK. Maximum allowed for tungsten dip is 55W
BTW, there is quite a bit of difference in light output between car
headlight bulbs with nominally the same wattage. With cheap ones being the
worst. Also halogen bulbs loose efficiency with time.
*Why does the sun lighten our hair, but darken our skin?
Dave Plowman email@example.com London SW
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