lumens vs.watts?

[[email protected]]

Is there a conversion or equivilant for a 12 volt,4 watt bulb that I
cannot find? All the bulbs now seem to be rated in lumens (eg. 25
lumens). I would like to find one that is the same brightness as the
original 4 watt bulb. The 25 lumens about half as bright as the
original but I cannot find any bulbs in this size with more lumens ! !

 

[Phil Allison]

<[email protected]

Is there a conversion or equivilant for a 12 volt,4 watt bulb that I
cannot find? All the bulbs now seem to be rated in lumens (eg. 25
lumens). I would like to find one that is the same brightness as the
original 4 watt bulb. The 25 lumens about half as bright as the
original but I cannot find any bulbs in this size with more lumens ! !

** You need to identify the original bulb correctly, it may be a special
type.

For example, Halogen or QI bulbs are brighter than standard ones.

Operating voltage has a big effect too - most so called 12 volt bulbs are
rated for automotive use at 14 volts.

Brightness and lifespan are interchangeable, if you apply more volts to a
blub it will be brighter but for a shorter time.




........ Phil

 

[Nobody]

Is there a conversion or equivilant for a 12 volt,4 watt bulb that I
cannot find? All the bulbs now seem to be rated in lumens (eg. 25
lumens). I would like to find one that is the same brightness as the
original 4 watt bulb. The 25 lumens about half as bright as the
original but I cannot find any bulbs in this size with more lumens ! !

The lumen is a measure of visible light output, weighted according to the
sensitivity of the human eye, while the Watt is a measure of total power.

The relationship between the two depends upon what proportion of the power
is emitted as visible light, and which wavelengths. This depends upon the
type of bulb and the voltage (e.g. a 110V, 100W tungsten filament bulb
tends to produce more lumens than a similar 240V, 100W bulb).

 

[Phil Allison]

"Nobrain & nobody TROLL "

The lumen is a measure of visible light output, weighted according to the
sensitivity of the human eye, while the Watt is a measure of total power.

** Irrelevant.

The relationship between the two depends upon what proportion of the power
is emitted as visible light, and which wavelengths. This depends upon the
type of bulb and the voltage (e.g. a 110V, 100W tungsten filament bulb
tends to produce more lumens than a similar 240V, 100W bulb).

** So applying more voltage produces less light ???

The simplest bot could do a better job of cribbing drivel like this from
Google.





......... Phil

 

[Bob Myers]

Is there a conversion or equivilant for a 12 volt,4 watt bulb that I
cannot find? All the bulbs now seem to be rated in lumens (eg. 25
lumens). I would like to find one that is the same brightness as the
original 4 watt bulb. The 25 lumens about half as bright as the
original but I cannot find any bulbs in this size with more lumens ! !

The two units don't convert directly - "lumens"
is a measure of the amount of light (specifically,
the amount of luminous flux, which is a measure
of the perceived power of the light source), while
the "watt" measurement only gives the total power
dissipated by the bulb (a great deal of which becomes
heat, not visible light). You have to know the
luminous efficacy of the bulb, or at least the typical
efficacy for that technology, to even begin to get
from watts to lumens. For instance, incandescent
bulbs (which are among the poorest technologies
in this regard - they're popular mostly because they're
cheap and have a pretty decent color) are typically
in the 5-18 lm/W range. A 25 lumen, 4W bulb is
just a bit above 6 lm/W, not bad for a low-wattage
incandescent but certainly not outstanding either.
You could likely do far better, for instance, with an
LED "bulb," if you can find one with a compatible
base.

Bob M.

 

[Nobody]

** Irrelevant.

When someone asks how to convert between lumens and Watts, the fact
they're measuring different things is quite relevant.

** So applying more voltage produces less light ???

Remember that they're both rated at 100W at their specified voltage. This
isn't a case of applying 240V to a 110V bulb.

240V bulbs tend to have a lower filament temperature, hence slightly more
of the power is emitted as infra-red and less as visible light.

 

[Gareth]

When someone asks how to convert between lumens and Watts, the fact
they're measuring different things is quite relevant.


Remember that they're both rated at 100W at their specified voltage.
This isn't a case of applying 240V to a 110V bulb.

240V bulbs tend to have a lower filament temperature, hence slightly
more of the power is emitted as infra-red and less as visible light.

Yes, because the higher voltage bulb has a higher resistance the
filament has to be longer and/or thinner, it is therefore mechanically
weaker and cannot be run as hot.

--

 

[Phil Allison]

"Nobody"

When someone asks how to convert between lumens and Watts,

** Was never asked for - fuckwit.

Remember that they're both rated at 100W at their specified voltage.

** YOU are an Gooogling IDIOT

PISS OFF !~!!




........ Phil

 

[Howard Eisenhauer]

Is there a conversion or equivilant for a 12 volt,4 watt bulb that I
cannot find? All the bulbs now seem to be rated in lumens (eg. 25
lumens). I would like to find one that is the same brightness as the
original 4 watt bulb. The 25 lumens about half as bright as the
original but I cannot find any bulbs in this size with more lumens ! !

FWIW I was perusing light bulbs at the local Home Despot the other day
& I noticed, sitting right next to each other, two bulbs, both
incandescant, same wattage rating but different lumen ratings- by
about 25-30% IIRC.

H.

 

[Michael A. Terrell]

FWIW I was perusing light bulbs at the local Home Despot the other day
& I noticed, sitting right next to each other, two bulbs, both
incandescant, same wattage rating but different lumen ratings- by
about 25-30% IIRC.

If they are both standard incandescent lamps, the lower lumen one is
a longer life bulb.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Rich Grise]

FWIW I was perusing light bulbs at the local Home Despot the other day
& I noticed, sitting right next to each other, two bulbs, both
incandescant, same wattage rating but different lumen ratings- by
about 25-30% IIRC.

Was one of them "long-life" or "heavy duty?"

Thanks,
Rich

 

[Tam/WB2TT]

Yes, because the higher voltage bulb has a higher resistance the
filament has to be longer and/or thinner, it is therefore mechanically
weaker and cannot be run as hot.

I recall high end photographic slide projectors used to have 24 V bulbs.

Tam

 

[Howard Eisenhauer]

If they are both standard incandescent lamps, the lower lumen one is
a longer life bulb.

Now that you mention it I do believe that was the case-

H.

 

[Don Klipstein]

"Nobrain & nobody TROLL "


** Irrelevant.


** So applying more voltage produces less light ???

Not quite, higher design voltage makes a filament longer and thinner and
for a given wattage and life expectancy, the longer thinner filament is
less efficient.

- Don Klipstein ([email protected])

 

[Don Klipstein]

FWIW I was perusing light bulbs at the local Home Despot the other day
& I noticed, sitting right next to each other, two bulbs, both
incandescant, same wattage rating but different lumen ratings- by
about 25-30% IIRC.

This is rather common.

1. One lamp may have a design life expectancy of 750 hours and the other
may have a design life expectancy of 3500 or 5000 hours. This alone could
make one have luminous efficacy about 15% more than the other.

2. One lamp may be a 120V one with a coiled-coil filament with
"visible overall length" about 25 mm, and the other may be a 120V one with
a singly coiled filament with "visible overall length" maybe 40 mm and a
smaller "overall diameter", along with multiple filament supports to
improve resistance to mechanical shock and vibration. The filament with
longer, thinner overall dimensions has a thinner "boundary layer" of hot
gas between the filament and surrounding cooler gas, and the temperature
gradient in the gas adjacent to the filament would be greater. This means
more heat conduction from the filament to the surrounding gas.
In addition, the filament supports will conduct a bit of heat from the
filament.
These factors could mean a 10-15% difference in overall luminous
efficacy, more in lamps of lowest current design to be able to be designed
for better efficiency with a fill gas than with a vacuum (probably
somewhere around .2 amp for most lamps designed for 12 volts or more).

3. One lamp may be of higher quality than the other.

All of these factors combined can make quite a difference. A 100 watt
120V 750 hour lamp of a "Big 3" brand and with a coiled-coil filament is
typically rated to produce 1710-1750 lumens.
A 100 watt 120V 1000 hour off-brand one with a singly coiled
multi-supported filament and made by a lower price
"lower-than-Big-3-quality" Chinese manufacturer may be rated to produce
1100 lumens.

4. Lower design voltage for a given wattage and life expectancy means a
shorter, thicker filament. The thicker filament can be operated at a
slightly higher temperature for the same life expectancy. The thicker
filament has less heat conduction loss per unit area by fill gas as
explained in #2 above.
Decreasing the design voltage increases luminous efficacy until the
filament gets so short and thick that heat conduction through the ends of
the filament becomes a really significant loss. Among 100 watt lamps,
the design voltage that maximizes overall luminous efficacy tends to be
a little over 12 volts (with a singly coiled filament).
I look among "100A" (100 watt "medium screw base" "regular
lightbulb shape and size" incandescent lamps in my "Philips catalog"
("SAG-100" printed 9/99), and the 12 volt version is rated to have an
average life expectancy of 1,000 hours and to produce 2050 lumens.
The 34 volt version is rated to produce 1940 lumens (1000 hours).
The 230V version is rated to produce 1270 lumens (1000 hours).
The 277 volt version is rated to produce 1070 lumens (1000 hours).

Various 120-130 volt versions are rated to produce 1560-1730 lumens
if designed to last 750 hours.

5. Halogen version makes a little difference - the bulb of a halogen
lamp is much more compact (since the halogen cycle allows a much more
compact bulb by keeping it clean of condensed tungsten vapor) and the
fill gas pressure is much higher because of a smaller sturdier bulb made
of tougher material. This along with the halogen cycle achieves longer
filament life and also a slight increase in filament temperature.
The Philips "Halogena" 100 watt 120V version produces 1670 lumens while
achieving a life expectancy of 3000 hours.

The small size of the bulb used in a halogen lamp (and also
longer life) reduces the economic penalty of using a premium main inert
fill gas ingredient. Sylvania appears to me to use krypton rather than
argon as the main inert fill gas ingredient in at least some of their
"Capsylite" lamps, and their current 100 watt 120V version A19 medium
screw base version of those is rated to last 3,000 hours and to produce
1800 lumens. (Sylvania product number 18970, order abbreviation
100A/HAL/F 120V)
I remember an older version from the early 1990's claimed to produce
1880 (give or take) lumens and to last 2250 (give or take) hours - I hope
I remember correctly! I do remember a different bulb shape - not an "A"
bulb shape, but with the wider region consisting of two butt-to-butt
truncated cones.

- Don Klipstein ([email protected])

 

[Phil Allison]

"Don Klipstein"

Not quite,

** My Q was rhetorical - you fool.

 

[Don Lancaster]

FWIW I was perusing light bulbs at the local Home Despot the other day
& I noticed, sitting right next to each other, two bulbs, both
incandescant, same wattage rating but different lumen ratings- by
about 25-30% IIRC.

H.

The lumens per watts measures the efficiency of the bulb.

A typical incandescent is around 15 lumens per watt.

Differences arise if a halogen cycle is used or if there are temperature
versus lifetime tradeoffs. Or if shaped "effective lumens" rather than
real ones are used in sort of an antenna pattern type of thingy.

The latest of LED's are approaching 150 Lumens per watt.

A perfect green bulb would be 700 Lumens per watt.
A perfect white one would be half that.

Older tutorial at http://www.tinaja.com/glib/muse95.pdf



--
Many thanks,

Don Lancaster voice phone: (928)428-4073
Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
rss: http://www.tinaja.com/whtnu.xml email: [email protected]

Please visit my GURU's LAIR web site at http://www.tinaja.com

 

[Don Klipstein]

The latest of LED's are approaching 150 Lumens per watt.

Where can I get one? I thought only laboratory prototypes got that
efficient so far. The most efficient LEDs that I am aware of being in
production and on the market achieve about 80 lumens/watt.

A perfect green bulb would be 700 Lumens per watt.

683 by definition for 540 THz, approx. 555 nm.

http://www.bipm.org/en/si/si_brochure/chapter2/2-1/candela.html

A perfect white one would be half that.

Depends on what you call white. If the "white light" is equal power per
unit wavelength from 400 to 700 nm, then light source that is 100%
efficient at producing such light and nothing outside the 400-700 nm
range would achieve 243 lumens per watt.

However, other forms of "white light" can get higher. A perfectly 100%
efficient light source producing a mixture of 576 nm yellow and 450 nm
blue to approximate the color of 3500K would achieve 495 lumens per watt.

- Don Klipstein ([email protected])

 

[Don Lancaster]

Where can I get one? I thought only laboratory prototypes got that
efficient so far. The most efficient LEDs that I am aware of being in
production and on the market achieve about 80 lumens/watt.




683 by definition for 540 THz, approx. 555 nm.

http://www.bipm.org/en/si/si_brochure/chapter2/2-1/candela.html




Depends on what you call white. If the "white light" is equal power per
unit wavelength from 400 to 700 nm, then light source that is 100%
efficient at producing such light and nothing outside the 400-700 nm
range would achieve 243 lumens per watt.

However, other forms of "white light" can get higher. A perfectly 100%
efficient light source producing a mixture of 576 nm yellow and 450 nm
blue to approximate the color of 3500K would achieve 495 lumens per watt.

- Don Klipstein ([email protected])

The LED trade journal is full of high efficiency leds.

http://www.ledjournal.com/

one of our banner advertisers is an industry insider with special
efficiency expertise ...

http://www.hdslights.com/


--
Many thanks,

Don Lancaster voice phone: (928)428-4073
Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
rss: http://www.tinaja.com/whtnu.xml email: [email protected]

Please visit my GURU's LAIR web site at http://www.tinaja.com

 

[Don Klipstein]

The LED trade journal is full of high efficiency leds.

http://www.ledjournal.com/

one of our banner advertisers is an industry insider with special
efficiency expertise ...

http://www.hdslights.com/

Thanks!

Meanwhile, I do frequently check into http://www.ledsmagazine.com

- Don Klipstein ([email protected])