Does anyone have any idea how long I should expect the headlight bulb to last? I've just had the low beam go, which is the second while I've owned the bike. I have put more than 50,000km on the bike, and leave the headlight on all the time, so the bulb has been used a bit.

If there's an overload it's obviously not serious, but does anyone have any data points?

A friend changed the tail-light bulb on his 90/6 after 35 years.


Al

Am on Ks for 4 years and not had to but have replaced one or two in the car in that time. Main thing is to watch the fitting to make sure the glass is not touched and also that the bulb socket is fully and securely fitted as in a good mechanical connection on all 3 pins. But a second in 4 years is not too bad. A Rover 75 at home will not go 3 months without losing a bulb.....I reckon a second at 50k isn't too bad.....and you probably don't know how long the other was in it before you got the K?

I wouldn't think that to be excessive but if it gets more regular then may pay to have a look at the connections at the bulb as slightly lose connections will cause that type of failure. The faster than we can see flickering will cause the filament to shed material and make it more likely to fail.

92KK K100LT 193214 wrote:A Rover 75 at home will not go 3 months without losing a bulb.....

Gees now that brings back memories it was a Rover 75 P3 that was my first road car but it didn't take me long to hotrod it with a 283 Chev and a 9" rear end and chrome wheels etc that went with all the hotrod stuff then.

My 90 K75RT got 40K out of the stock halogen bulb.

I wish the Rover was a P5 in particular the P5B coupe. A nice 3.5 V8......My favourite classic.

But the 75 at home is the more modern one, built from 1999 to 2005, initially under the ownership of BMW. In some places it was sold with the 4.6 V8 found in Range Rovers but this one has the BMW common rail diesel engine [shared with 320d and 520d of the same era] mated to automatic transmission.

The 75 P3 is well before my time...... but also a nice motor.

My bulb, recently replaced, had 43000 KM on it. Probably would have lasted longer but I buggered it removing the socket to install an Eastern Beaver relay kit.

If you are running the standard halogen headlight bulb then it thrives on heat, the hotter the better. If you supply it with a lower voltage then it will run cooler and the metals within the bulb will coat the quartz glass and not burn off. In the past the bulbs that have lasted the longest for me are the ones where I have played with the wires to make both filaments burn at the same time when on main beam.
It is bad practice to have the headlight on when the engine is not running as the battery could be a little low in voltage and will take a little life from the bulb.

hate to say it .....
but most suppliers have economized their manufacture processes

the filament stretches and shrinks to the heating effect ...

and over time becomes brittle ..

every time a globe turns on the shock to the element is at a premium, whilst it goes from a very low resistance to a slightly higher one and current dissipates some what  ( the strike current can be many times what the working current is ...)

the primary factor for globe failure is the purity of the gas in the envelope of the globe which directly affects the durability and shedding of the heated element of the globe and the actual fabrication elements of the filament ..

not many years ago we saw the same thing happening with (cathode ray ) tvs and monitors   once the Chinese - Korean et all became involved in tube ...globe manufacture, the death rate increased extraordinarily ...name brands that used to be considered as stalwarts of production values started seeing massive early failure rates after... erm dubious design and plating standards used .....which also brought lower cost ....

no oxygen ...no deterioration ...well as much anyhow !! and poor quality  elements used in both the filament and rare gasses production just means early failure

I too have had globes last a decade or more ...till recently , I find that even the rear running lamp needs to be replaced every 18 months or less ....there are some dodgy brands  out there

I keep seeing cars as young as 10 years(and younger )  with 4 out of 5 brake lamps failed all the time

not to mention head lamps ...crikey they go off fast these days

The typical standard halogen H4 or now more common H7 on BMWs used to last a coupla years at least with no worries (headlight always on models), but I've seen a notable increase in bulbs lasting only a year or less. I agree with Charlie that with the dumbing down of the manufacturing process, and often just plain poor quality, Chinese made versions, most are crap. I try to stock BMW's versions, or Osram, Phillips, etc., but you can never be sure where they come from. Also, late model CAN-Bus BMWs 'eat' headlight bulbs, which might be explained because the ZFE is constantly monitoring the voltage and this may have an effect on the filament's life. A newer R1200GS or RT will chew through them in six months' time. PIAA seem not to last either, in any type of 'bike. Having said that on my K1200S I managed two years on the low beam and never replaced the high beam, but on my RT I've swapped the low beam twice in a year and a half - daily ridden. Still, I use that brand in my bikes. Their light output is beaut. I reckon I've never replaced the H4 in my K100RS, after trying a high output 90/100W for a while which slightly melted the three way connector - that's another story (read, needs an Eastern Beaver mod). It's now a bog stock 55/60W H4 from Osram.

I too am sure that 'they don't make 'em like they used to' when it comes to headlamp bulbs.  Having said that, Osram do a longlife bulb that has given me good results in my current car.

I did own a Hyundai Trajet that absolutely destroyed bulbs on a regular basis, but only on the nearside.  I am certainly no electrical genius, and I was truly baffled by this habit.  It did not seem to matter whether I used good quality stuff, or cheap rubbish; bulb life was rarely more than three months.