Halogen bulbs

[Mainlander]

As noted in my post in nz.tech I am having difficulty sourcing an H3 6V
15W bulb for a cordless rechargeable spotlight. I have since discovered
this type is virtually unobtainable in Australasia.

Calculations based on a 12V 55W bulb drawing approx 4.6 A @ full power
suggests when operated on 6V the current should be halved to 2.3A, this
gives a power of 14W which is acceptably close to the output of the
original bulb. However this assumes the lamp is as efficient at the lower
voltage as at full voltage, can halogens be "dimmed" or operated at lower
voltage with the same efficiency?

It appears the problem in this particular spotlight light is not the
bulb, but a break in the track of the small internal PCB, however in the
course of attempting to find a replacement the bulb has been handled so
much that its life will be shortened in any case.

The advantage is that 12V 55W is a very commonly available size for the
H3 bulb that is commonly used in automotive applications and these
rechargeable handheld spotlights. Most such lights have a rating of 30 -
55W with correspondingly shorter battery life.

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[Richard Malcolm-Smith]

Mainlander wrote:

As noted in my post in nz.tech I am having difficulty sourcing an H3 6V
15W bulb for a cordless rechargeable spotlight. I have since discovered
this type is virtually unobtainable in Australasia.

The place you bought the lamp from will be able to help, if not then they are
not providing spares for the product they sell, so you can get it resolved under
the consumer guarenties act, possible a new light or similar.

 

[John Tserkezis]

Mainlander wrote:

As noted in my post in nz.tech I am having difficulty sourcing an H3 6V
15W bulb for a cordless rechargeable spotlight. I have since discovered
this type is virtually unobtainable in Australasia.

I've found it difficult to obtain just about any higher power 6v halogen. I
was trying to get more lighting power for my bicycle lights, and gave up
looking for spares and higher powers. I went to 12v halogens. Disregarding
the mounting issues, they are a LOT cheaper and a LOT easier to obtain.

Calculations based on a 12V 55W bulb drawing approx 4.6 A @ full power
suggests when operated on 6V the current should be halved to 2.3A, this
gives a power of 14W which is acceptably close to the output of the
original bulb. However this assumes the lamp is as efficient at the lower
voltage as at full voltage, can halogens be "dimmed" or operated at lower
voltage with the same efficiency?

You can't do that with halogens (or normal incandescents for that matter),
reducing the voltage will greatly reduce their output, because of that, reduce
their temperature, and because of that, reduce the filament regeneration cycle.
Lastly, it's the halogen filament regeneration that gives them their long life.
The exception is normal incandescents, which benefit from a longer life if
you run them at lower than rated voltage.

Also, operating an incancescent or halogen lamp at lower than their rated
voltage tends to shift the output closer to infrared, so you get more heat and
less light for your watts. (less efficient). Anectodal evidence (well, google)
says dimming a 500W mains operated halogen to 300W will give you equivalent
light output as a 40W bulb. You get the idea, dimming battery operated lights
is generally not a good idea if you're looking at improving battery life.

It appears the problem in this particular spotlight light is not the
bulb, but a break in the track of the small internal PCB, however in the
course of attempting to find a replacement the bulb has been handled so
much that its life will be shortened in any case.

Can't you repair this break? I don't think it's rocket science...

On the note of halogen handling, if you haven't powered it up since touching
it, cleaning it with alcohol then water will remove the oils from the surface
(which cause the trouble).

The advantage is that 12V 55W is a very commonly available size for the
H3 bulb that is commonly used in automotive applications and these
rechargeable handheld spotlights. Most such lights have a rating of 30 -
55W with correspondingly shorter battery life.

Not if you can't supply 12v to operate them. (Or can you?)

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[Mainlander]

In article <bu33ot$4ah$1@lust.ihug.co.nz>, rich@ihug.co.nz says...

Mainlander wrote:

As noted in my post in nz.tech I am having difficulty sourcing an H3 6V
15W bulb for a cordless rechargeable spotlight. I have since discovered
this type is virtually unobtainable in Australasia.

The place you bought the lamp from will be able to help, if not then they are
not providing spares for the product they sell, so you can get it resolved under
the consumer guarenties act, possible a new light or similar.

I want to keep this one if possible because it has a much more useful 90
minute battery life than most of the bigger ones which run for only 30
minutes, thus I would rather have a bulb for it than replace it with a
bigger one.

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[Mainlander]

In article <40054174$0$14483$afc38c87@news.optusnet.com.au>,
jt@techniciansyndrome.org.invalid says...

Mainlander wrote:

As noted in my post in nz.tech I am having difficulty sourcing an H3 6V
15W bulb for a cordless rechargeable spotlight. I have since discovered
this type is virtually unobtainable in Australasia.

I've found it difficult to obtain just about any higher power 6v halogen. I
was trying to get more lighting power for my bicycle lights, and gave up
looking for spares and higher powers. I went to 12v halogens. Disregarding
the mounting issues, they are a LOT cheaper and a LOT easier to obtain.

The 6V 30W and 55W sizes are relatively easy to obtain in Australia and
elsewhere.

Calculations based on a 12V 55W bulb drawing approx 4.6 A @ full power
suggests when operated on 6V the current should be halved to 2.3A, this
gives a power of 14W which is acceptably close to the output of the
original bulb. However this assumes the lamp is as efficient at the lower
voltage as at full voltage, can halogens be "dimmed" or operated at lower
voltage with the same efficiency?

You can't do that with halogens (or normal incandescents for that matter),
reducing the voltage will greatly reduce their output, because of that, reduce
their temperature, and because of that, reduce the filament regeneration cycle.
Lastly, it's the halogen filament regeneration that gives them their long life.

250 hours is a "long life"? That is the rated life of most of these
bulbs, I would not call that long.

The exception is normal incandescents, which benefit from a longer life if
you run them at lower than rated voltage.

Also, operating an incancescent or halogen lamp at lower than their rated
voltage tends to shift the output closer to infrared, so you get more heat and
less light for your watts. (less efficient). Anectodal evidence (well, google)
says dimming a 500W mains operated halogen to 300W will give you equivalent
light output as a 40W bulb. You get the idea, dimming battery operated lights
is generally not a good idea if you're looking at improving battery life.

It appears the problem in this particular spotlight light is not the
bulb, but a break in the track of the small internal PCB, however in the
course of attempting to find a replacement the bulb has been handled so
much that its life will be shortened in any case.

Can't you repair this break? I don't think it's rocket science...

On the note of halogen handling, if you haven't powered it up since touching
it, cleaning it with alcohol then water will remove the oils from the surface
(which cause the trouble).

The advantage is that 12V 55W is a very commonly available size for the
H3 bulb that is commonly used in automotive applications and these
rechargeable handheld spotlights. Most such lights have a rating of 30 -
55W with correspondingly shorter battery life.

Not if you can't supply 12v to operate them. (Or can you?)

Even if I could supply 12V I couldn't get a 15W one, because if the
fitting is designed for 15W higher power lamps are likely to cause damage
from the extra heat.

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[Bruce Simpson]

On Wed, 14 Jan 2004 22:43:55 +1300, Mainlander <*@*.*> wrote:

Calculations based on a 12V 55W bulb drawing approx 4.6 A @ full power
suggests when operated on 6V the current should be halved to 2.3A, this
gives a power of 14W which is acceptably close to the output of the
original bulb.

Unfortunately, because most bulbs have a positive temperature
coefficient of resistance and the filiament undergoes a marked change
in temperature, the current drawn at half voltage will be much less
than half that drawn at full voltage.

You may find that you get far less than 14W from that bulb -- in fact
it might glow a rather dull red rather than white. What's worse, if
it's a hallogen then the hailides inside will not operate as designed
at these lower temperatures so the bulb life may be affected.

--
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[Brummer]

Jaycar sell 55W, 25W and 10W in 6V versions, specifically for torches and
spotlights.

 

[Phil Allison]

"Bruce Simpson" <

Calculations based on a 12V 55W bulb drawing approx 4.6 A @ full power
suggests when operated on 6V the current should be halved to 2.3A, this
gives a power of 14W which is acceptably close to the output of the
original bulb.

Unfortunately, because most bulbs have a positive temperature
coefficient of resistance and the filament undergoes a marked change
in temperature, the current drawn at half voltage will be much less
than half that drawn at full voltage.

** A filament bulb tends towards a constant current characteristic -
i.e. the current does NOT change in proportion to the applied voltage. At
half the nominal voltage the current will be around 75%.

As you said, there is a strong positive temperature coefficient in the
tungsten wire - about *12 times* increase in resistance from cold to hot.





.............. Phil

 

[John Tserkezis]

Mainlander wrote:

The 6V 30W and 55W sizes are relatively easy to obtain in Australia and
elsewhere.

Ah, ok, but you say you'd rather not use these due to the lesser battery
life... They're probably too bright anyway.

250 hours is a "long life"? That is the rated life of most of these
bulbs, I would not call that long.

250 hours!? Stuff that for a joke. I'm using standard 35mm, 7degree 12W 12V
downlights on the bicycle. 2000 hours life. I break them before I run out of
life. And at less that AU$20 a pop, who cares?

Retrofitting one into a largish frame torch might need a bit of imagination
and perhaps lateral thinking, but certainly doable.

If you don't care about how it looks, you could bodgy up a plain 6v lantern
battery type torch, even fan force it if you need to, and replace the 6v
lantern style battery with a 4A/Hr SLA battery. Would probably still end up
being cheaper than the fancy 6v torches.

Even if I could supply 12V I couldn't get a 15W one, because if the
fitting is designed for 15W higher power lamps are likely to cause damage
from the extra heat.

True. I was in a similar boat with my bike lights. I had spent stupid
amounts of money on them, and they were all not quite bright enough, or didn't
have enough light spread.
In the end I wrote off the money I had already spent as a lesson learned and
went the downlight route.
Cheap, simple, and does the job.

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[Phil Allison]

"John Tserkezis"

250 hours is a "long life"? That is the rated life of most of these
bulbs, I would not call that long.

250 hours!? Stuff that for a joke. I'm using standard 35mm, 7degree
12W 12V
downlights on the bicycle. 2000 hours life.

** The life of a lamp is a function of brightness and efficiency - the
more the less.

2000 hr rated life lamps are dull, yellowish and inefficient - for AC
mains operation no problem.

50 hr rated life ones (as used in 35mm slide projectors) are brilliant
white and have way more lumens per watt - essential for good colour temp
and image quality.

Torch bulbs typically have short lives - maybe only 10- 20 hours at full
voltage - for a reason.




........... Phil

 

[Mainlander]

In article <40068669$0$14485$afc38c87@news.optusnet.com.au>,
jt@techniciansyndrome.org.invalid says...

Mainlander wrote:

The 6V 30W and 55W sizes are relatively easy to obtain in Australia and
elsewhere.

Ah, ok, but you say you'd rather not use these due to the lesser battery
life... They're probably too bright anyway.

Can't use a 30W bulb in a fitting designed for 15W bulbs.

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[Mainlander]

In article <40068bec$0$4048$afc38c87@news.optusnet.com.au>,
philallison@optusnet.com.au says...

"John Tserkezis"

250 hours is a "long life"? That is the rated life of most of these
bulbs, I would not call that long.

250 hours!? Stuff that for a joke. I'm using standard 35mm, 7degree
12W 12V
downlights on the bicycle. 2000 hours life.



** The life of a lamp is a function of brightness and efficiency - the
more the less.

2000 hr rated life lamps are dull, yellowish and inefficient - for AC
mains operation no problem.

50 hr rated life ones (as used in 35mm slide projectors) are brilliant
white and have way more lumens per watt - essential for good colour temp
and image quality.

Torch bulbs typically have short lives - maybe only 10- 20 hours at full
voltage - for a reason.

The H3 / H4 bulbs are automotive types typically quoted 250 hours by
suppliers

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[Phil Allison]

"Mainlander" <*@*.*> wrote in message
news:MPG.1a720e6db0611c8098a480@news.paradise.net.nz...

In article <40068bec$0$4048$afc38c87@news.optusnet.com.au>,
philallison@optusnet.com.au says...

"John Tserkezis"

250 hours is a "long life"? That is the rated life of most of these
bulbs, I would not call that long.

250 hours!? Stuff that for a joke. I'm using standard 35mm,
7degree
12W 12V
downlights on the bicycle. 2000 hours life.



** The life of a lamp is a function of brightness and efficiency -
the
more the less.

2000 hr rated life lamps are dull, yellowish and inefficient - for
AC
mains operation no problem.

50 hr rated life ones (as used in 35mm slide projectors) are brilliant
white and have way more lumens per watt - essential for good colour
temp
and image quality.

Torch bulbs typically have short lives - maybe only 10- 20 hours at
full
voltage - for a reason.


The H3 / H4 bulbs are automotive types typically quoted 250 hours by
suppliers

** And your point is ??????



............. Phil

 

[David Kinsell]

"Bruce Simpson" <checksigformyre@l.address> wrote in message newscbb00ll4bo3bml2d8ri4krh42bogfp8ah@4ax.com...

On Wed, 14 Jan 2004 22:43:55 +1300, Mainlander <*@*.*> wrote:

Calculations based on a 12V 55W bulb drawing approx 4.6 A @ full power
suggests when operated on 6V the current should be halved to 2.3A, this
gives a power of 14W which is acceptably close to the output of the
original bulb.

Unfortunately, because most bulbs have a positive temperature
coefficient of resistance and the filiament undergoes a marked change
in temperature, the current drawn at half voltage will be much less
than half that drawn at full voltage.

Actually, the current will be significantly more than half that drawn at full voltage.

You may find that you get far less than 14W from that bulb -- in fact
it might glow a rather dull red rather than white. What's worse, if
it's a hallogen then the hailides inside will not operate as designed
at these lower temperatures so the bulb life may be affected.

True, it's not going to operate very well at half voltage. The spectral
density will be way off and lifetime could be terrible due to due to deposits
on the envelope.

--
you can contact me via http://aardvark.co.nz/contact/

 

[larry]

hi,

"Mainlander" <*@*.*> wrote in message
news:MPG.1a720e6db0611c8098a480@news.paradise.net.nz...

In article <40068bec$0$4048$afc38c87@news.optusnet.com.au>,
philallison@optusnet.com.au says...

"John Tserkezis"

250 hours is a "long life"? That is the rated life of most of these
bulbs, I would not call that long.

250 hours!? Stuff that for a joke. I'm using standard 35mm,
7degree
12W 12V
downlights on the bicycle. 2000 hours life.



** The life of a lamp is a function of brightness and efficiency -
the
more the less.

2000 hr rated life lamps are dull, yellowish and inefficient - for
AC
mains operation no problem.

50 hr rated life ones (as used in 35mm slide projectors) are brilliant
white and have way more lumens per watt - essential for good colour
temp
and image quality.

Torch bulbs typically have short lives - maybe only 10- 20 hours at
full
voltage - for a reason.

The H3 / H4 bulbs are automotive types typically quoted 250 hours by
suppliers

--

thanks for the info.
I never knew this before
it explains a lot

laz

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