Red uses more power than White LEDs?

U

UnknownVT

Flashlight Enthusiast
Joined
Dec 27, 2002
Messages
3,672
I brought this up in my post about an eternaLight Ergo 3 Red/White option -

eternaLight Ergo 3 Red/White

Please look at this extract from the manual:

ergo3BatteryLife.gif


Notice that the 2 Reds have HALF the battery life of 2 Whites (or greens).

It has always been my understanding that the longer wavelength LEDs like red, orange, and yellow have a lower Vf and use significantly less power than the equivalent white, and shorter wavelength (blue, green) LEDs.

So what gives?
Why does the eternaLight use TWICE the power when on Red LEDs than on White (or green) LEDs?

Anyone?

Thanks,
 
L

Lurker

Flashlight Enthusiast
Joined
Nov 6, 2002
Messages
1,457
Location
The South
Either they labelled the columns incorrectly or maybe there is something wierd in the design, maybe they are using overly large resistors on the reds or something.
 
U

UnknownVT

Flashlight Enthusiast
Joined
Dec 27, 2002
Messages
3,672
[ QUOTE ]
Lurker said: Either they labelled the columns incorrectly or maybe there is something wierd in the design, maybe they are using overly large resistors on the reds or something.

[/ QUOTE ]

Thanks for the suggestions - I wrote e-mail to Techass.com and got this reply:
-----------------------------------------------------------
From : @techass.com
Sent : Monday, January 31, 2005 9:28 PM
To : V T
Subject : Re: Red uses more power than White LEDs? - eternaLight Model 3 Ergo Red/White

Dear VT,

It is because the circuit was designed for the voltage of the white, blue, green or UV leds. The RED and Yellow cut off lower so more current is drawn.

Best regards,

Tom

---------------------------------------------------------

V T wrote:

Dear Tech Associates,

I have recently purchased an eternaLight Model 3 Ergo Red/White Option -

According to the supplied manual it seems that the 2 Red LEDS have HALF the battery life of 2 Whites (or greens).

It has always been my understanding that LEDs of longer wavelengths like red, orange and yellow use significantly less power than the equivalent White or shorter wavelength (blue, green) LEDs.

So how come on the eternaLight the Red LEDs seem to use TWICE the power of the White LEDs?

Please see these two threads on CPF:

Red uses more power than White LEDs?
http://www.candlepowerforums.com/ubbthreads/showflat.php?Cat=&Number=854074

eternaLight Ergo 3 Red/White
http://www.candlepowerforums.com/ubbthreads/showflat.php?Cat=&Number=843051

Appreciate any explanation on what seems like an anomoly to me.

Thanks,

--
Vincent
-----------------------------------------------------------
 
H

HarryN

Flashlight Enthusiast
Joined
Jan 22, 2004
Messages
3,941
Location
Pleasanton (Bay Area), CA, USA
I think a good place to start is to look at the Lumileds data sheets for the Luxeon I. The RED do have a lower Vf, but the eye is not especially sensitive to the traditional RED, which is approximately 640 nm. For this reason, the Lumens emitted with the same power are fairly low (eye sensitivity is a factor.)

If you move to a RED - ORANGE, (approx 615 - 620 nm), the eye is much more sensitive, and the Lumen output rises substantially for the same power. (nominal current 350 ma)

In the past, RED has always had much higher efficiency than blue, which is the starting point of white LEDs. The recent improvements in technology, are making this less true every day, and Blue / white are expected to move well beyone RED for efficiency.
 
U

UnknownVT

Flashlight Enthusiast
Joined
Dec 27, 2002
Messages
3,672
[ QUOTE ]
HarryN said: The RED do have a lower Vf, but the eye is not especially sensitive to the traditional RED, which is approximately 640 nm. For this reason, the Lumens emitted with the same power are fairly low (eye sensitivity is a factor.)

[/ QUOTE ]

Many thanks for the input.

The efficiency of the human eye to the wavength of light is an important factor for the utilization of a flashlight (and I realize that since I have difficulties seeing under red light - as does my digital camera(!) ).

However my point is a lot more simple minded than that -

Longer wavelength LEDs - like red, orange and yellow use SIGNIFICANTLY less power than their equivalent White or shorter wavelength (eg: blue, green) LEDs.

For example please take a look at the advertized battery life of the various color Photon LED lights in the Photon technical specs :

The red, orange, and yellow lights show a battery life of 120 hours
compared to
White, blue, green, turquoise, and purple of only 10-12 hours.


Whereas the eternaLight Model 3 Ergo battery life for the Red/White option shows HALF the battery life for the Red compared to the White.

Techass.com - the makers of the eternaLight gave the reason in their e-mail reply to me above.
 
F

FlashlightOCD

Enlightened
Joined
Apr 7, 2003
Messages
931
Location
Central FL, USA
Consider the following on the Inova X5:

Power source
* 2 CR123A (3 V) replaceable lithium batteries w/ 10-year shelf life
* Red light requires 1 CR123A battery
 
elgarak

elgarak

Flashlight Enthusiast
Joined
Jul 30, 2004
Messages
1,045
Location
Florida
And the battery runtime is the same for red/white Inovas. /ubbthreads/images/graemlins/huh.gif
 
U

UnknownVT

Flashlight Enthusiast
Joined
Dec 27, 2002
Messages
3,672
[ QUOTE ]
elgarak said:
And the battery runtime is the same for red/white Inovas. /ubbthreads/images/graemlins/huh.gif

[/ QUOTE ]

(1) The Red uses only one CR123 battery vs. 2x CR123 of the whites - so the red uses HALF the power of the white.

(2) I think Inova have simplified their specs - they have not given different runtimes for the Red and White separately.

Personally I think the runtime for the Red would be much higher in comparison to the White - as evidenced by the
Specs for the Inova 24/7
even though there isn't a direct comparision of Two whites on high vs. the two Red LEDs -
the Low white (x4) shows only 15hours vs. the 80hours of the two reds on high......
Or the 4x Whites on high gives 6hours - so 2x whites on high most probably is 12hours - vs. the 80hours of the Reds....

So, from this - given the same power source - Red LEDs would seem to give about 5 to 7x the battery life of the equivalent white LED.
 

Similar threads

M
Replies
0
Views
584
M
thefish
Replies
27
Views
3K
macforsale
macforsale
W
Replies
2
Views
1K
woodfluter
W
W
Replies
6
Views
7K
PhotonWrangler
PhotonWrangler
B
Replies
4
Views
2K
VidPro
V
Top