Filiament Degrade

[wymberley]

Hi, guys,

As Title: do bulbs lose their power with age/usage; talking 170 with a 100watt? The question has nothing to do with the battery.

Many thanks in anticipation,

Cheers

[Wrighty112]

Short answer is yes..

But there are alot of varibles... Battery power is one of the big ones. Depending on the milliamp per hour. Dictates the length of battery.

[Evil Elvis]

Been running a lightforce 170 for 2 years with a bigger than recommended bulb in it...could still light up wales from here lol.....So no....mine hasnt. :unsure:

[Rem223]

Depending on the milliamp per hour. Dictates the length of battery.

What does this mean?

 

Halogen bulbs are designed so that as tungsten boils off from the filament it combines with iodine to form a metal halide. This can then be split back to tungsten and iodine by the high temperature filament. With non halogen bulb you generally find the glass becomes blackened by tungsten deposits on the glass envelope. This problem is greatly reduced by the use of a halogen. It means the bulbs last much longer and do not suffer from dimming with age. However what then tends to happen is the tungsten does not get deposited evenly leading to thinner parts of the filament which eventually break. Usually when you switch on a cold bulb when the resistance is lowest and current therefore is greater. It is generally best to run halogen bulbs at their rated voltage. Reduced voltages tend to lead to lower lifespan as the halogen cycle doesn't work properly. So to answer your question there is little degradation in luminosity over the lifespan of a bulb provided you keep your battery well charged and don't run it down flat.

[wymberley]

Rem,

Brilliant, mate (no pun intended!). I had a feeling that with the bulbs in question that was the answer but couldn't back it up with the science. Just about to replace my battery. I know for a fact that I've had it for ten years but simply can't remember further back than that. I always have a spare bulb and as the 2 I have are the same age as the battery was toying with replacing them as well. Thanks to you, there's no need.

Again, many thanks,

Cheers,

Phil

[wymberley]

Short answer is yes..

But there are alot of varibles... Battery power is one of the big ones. Depending on the milliamp per hour. Dictates the length of battery.

Wrighty, hi,

Thanks, but I was purely talking about the bulb. However, I understand what you are quite rightly saying and what you have said explains why the battery has lasted so long (together with an occasional total discharge/recharge).

Cheers

[Dekers]

What does this mean?

 

Halogen bulbs are designed so that as tungsten boils off from the filament it combines with iodine to form a metal halide. This can then be split back to tungsten and iodine by the high temperature filament. With non halogen bulb you generally find the glass becomes blackened by tungsten deposits on the glass envelope. This problem is greatly reduced by the use of a halogen. It means the bulbs last much longer and do not suffer from dimming with age. However what then tends to happen is the tungsten does not get deposited evenly leading to thinner parts of the filament which eventually break. Usually when you switch on a cold bulb when the resistance is lowest and current therefore is greater. It is generally best to run halogen bulbs at their rated voltage. Reduced voltages tend to lead to lower lifespan as the halogen cycle doesn't work properly. So to answer your question there is little degradation in luminosity over the lifespan of a bulb provided you keep your battery well charged and don't run it down flat.

 

 

Took the words out of my mouth.....