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Does a dimmed LED lamp draw less when at full brightness?
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Does a dimmable 6W LED lamp, dimmed to 50%, draw c. 3W? Or does it still draw the full 6W?
power led dimming
edited 9 mins ago
Blair Fonville
2,4702826
asked 3 hours ago
user27511
22428
add a comment |Â
up vote
3
down vote
favorite
Does a dimmable 6W LED lamp, dimmed to 50%, draw c. 3W? Or does it still draw the full 6W?
power led dimming
edited 9 mins ago
Blair Fonville
2,4702826
asked 3 hours ago
user27511
22428
add a comment |Â
up vote
3
down vote
favorite
up vote
3
down vote
favorite
Does a dimmable 6W LED lamp, dimmed to 50%, draw c. 3W? Or does it still draw the full 6W?
power led dimming
edited 9 mins ago
Blair Fonville
2,4702826
asked 3 hours ago
user27511
22428
Does a dimmable 6W LED lamp, dimmed to 50%, draw c. 3W? Or does it still draw the full 6W?
power led dimming
power led dimming
edited 9 mins ago
Blair Fonville
2,4702826
asked 3 hours ago
user27511
22428
edited 9 mins ago
Blair Fonville
2,4702826
asked 3 hours ago
user27511
22428
edited 9 mins ago
Blair Fonville
2,4702826
edited 9 mins ago
Blair Fonville
2,4702826
edited 9 mins ago
Blair Fonville
2,4702826
2,4702826
asked 3 hours ago
user27511
22428
asked 3 hours ago
user27511
22428
asked 3 hours ago
user27511
22428
22428
add a comment |Â
add a comment |Â
3 Answers
3
active
oldest
votes
up vote
4
down vote
It depends on the LED driver, but unless it's of a bad (or very specific need) design, a dimmed LED lamp will draw less power.
Usually, dimming on LED lamps is done by PWM (Pulse Width Modulation). The LED will actually turn on and off faster than the eye can see. By modulating the ratio of the time the led is on and off, it simulates the dimming to the human eye.
This method is widely used because it is the cheapest and easiest method to dim an led but it can also cause some eye fatigue.
With this method the power will reduce with the light intensity (or perceived intensity).
Another method of controlling the light intensity of an LED is to control the current flow through the LED, and there are mostly 2 ways of doing it:
- Through DC/DC conversion like a current controlled buck converter or similar circuit.
in this case the current will reduce with the intensity of the LED. With this method, there will be little flicker, which will be roughly equivalent to the DC/DC converter ripple.
- Using an analog ballast (adjustable current source), like a transistor, mosfet or specialized IC with required regulation.
In this situation, the current will diminish but this circuit will likely have more losses.
The latest has the advantage of providing a very stable light intensity (if needed for some specific application perhaps like photography), so we can imagine this exists on the market.
The power will be reduced when the light intensity is reduced, but it's not a linear factor. F.I. 50% dimming might not have a 50% decrease on the power consumption.
The reason is that the control electronic will have some non-linearity and won't have the same efficiency at different operating condition and the second reason is that the eye intensity response is not linear to the actual light.
answered 3 hours ago
Damien
62517
1
In this situation, the power that is not used for the led is dissipated by the ballast that controls the current, in that case, the power input will be the same even when dimmed. No, the power input will be less because the current through the LED is less (unless the dimming is done by shunting the LED, which would be a strange way of doing it unless there was some very good reason to). As you say though, the relationship between power and brightness won't necessarily be linear.
– nekomatic
2 hours ago
You are right, thanks for pointing it out @nekomatic
– Damien
1 hour ago
add a comment |Â
up vote
2
down vote
I will use about half (except for the controller using a bit).
Probably PWM is used, this means a duty cycle of 50%, means the light is on only half of the time, many times per second though.
answered 3 hours ago
Michel Keijzers
4,88262150
add a comment |Â
up vote
2
down vote
In general yes, the LED itself will use less power when "dimmed". But we have to be a bit more specific what "dimmed" means.
So the answer depends a bit on how the dimming is done. If a pulse width modulation is used to control the LED's brightness, then the dissipated power scales directly with the pulswidth. This means full brightness is reached with max pulswidth what equals max power dissipation whereas as a reduced brightness requires less pulswidth and therefore dissipates less power.
Back in the days when light bulbs where used, dimming was done by so called phase angle control, comparable to something like AC pulse width modulation. And before that, you would just add a potentiometer as a pre-resistor. In that case, the bulb itself would dissipate less power when dimmed, but just because the resistor now burns the rest - so ovarall you had the same.
But long story short, when you use PWM, the power will scale with the pulse width. But consider that brightness doesn't scale linearly with dissipated power.
answered 3 hours ago
Humpawumpa
906113
add a comment |Â
3 Answers
3
active
oldest
votes
3 Answers
3
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
4
down vote
It depends on the LED driver, but unless it's of a bad (or very specific need) design, a dimmed LED lamp will draw less power.
Usually, dimming on LED lamps is done by PWM (Pulse Width Modulation). The LED will actually turn on and off faster than the eye can see. By modulating the ratio of the time the led is on and off, it simulates the dimming to the human eye.
This method is widely used because it is the cheapest and easiest method to dim an led but it can also cause some eye fatigue.
With this method the power will reduce with the light intensity (or perceived intensity).
Another method of controlling the light intensity of an LED is to control the current flow through the LED, and there are mostly 2 ways of doing it:
- Through DC/DC conversion like a current controlled buck converter or similar circuit.
in this case the current will reduce with the intensity of the LED. With this method, there will be little flicker, which will be roughly equivalent to the DC/DC converter ripple.
- Using an analog ballast (adjustable current source), like a transistor, mosfet or specialized IC with required regulation.
In this situation, the current will diminish but this circuit will likely have more losses.
The latest has the advantage of providing a very stable light intensity (if needed for some specific application perhaps like photography), so we can imagine this exists on the market.
The power will be reduced when the light intensity is reduced, but it's not a linear factor. F.I. 50% dimming might not have a 50% decrease on the power consumption.
The reason is that the control electronic will have some non-linearity and won't have the same efficiency at different operating condition and the second reason is that the eye intensity response is not linear to the actual light.
answered 3 hours ago
Damien
62517
1
In this situation, the power that is not used for the led is dissipated by the ballast that controls the current, in that case, the power input will be the same even when dimmed. No, the power input will be less because the current through the LED is less (unless the dimming is done by shunting the LED, which would be a strange way of doing it unless there was some very good reason to). As you say though, the relationship between power and brightness won't necessarily be linear.
– nekomatic
2 hours ago
You are right, thanks for pointing it out @nekomatic
– Damien
1 hour ago
add a comment |Â
up vote
4
down vote
It depends on the LED driver, but unless it's of a bad (or very specific need) design, a dimmed LED lamp will draw less power.
Usually, dimming on LED lamps is done by PWM (Pulse Width Modulation). The LED will actually turn on and off faster than the eye can see. By modulating the ratio of the time the led is on and off, it simulates the dimming to the human eye.
This method is widely used because it is the cheapest and easiest method to dim an led but it can also cause some eye fatigue.
With this method the power will reduce with the light intensity (or perceived intensity).
Another method of controlling the light intensity of an LED is to control the current flow through the LED, and there are mostly 2 ways of doing it:
- Through DC/DC conversion like a current controlled buck converter or similar circuit.
in this case the current will reduce with the intensity of the LED. With this method, there will be little flicker, which will be roughly equivalent to the DC/DC converter ripple.
- Using an analog ballast (adjustable current source), like a transistor, mosfet or specialized IC with required regulation.
In this situation, the current will diminish but this circuit will likely have more losses.
The latest has the advantage of providing a very stable light intensity (if needed for some specific application perhaps like photography), so we can imagine this exists on the market.
The power will be reduced when the light intensity is reduced, but it's not a linear factor. F.I. 50% dimming might not have a 50% decrease on the power consumption.
The reason is that the control electronic will have some non-linearity and won't have the same efficiency at different operating condition and the second reason is that the eye intensity response is not linear to the actual light.
answered 3 hours ago
Damien
62517
1
In this situation, the power that is not used for the led is dissipated by the ballast that controls the current, in that case, the power input will be the same even when dimmed. No, the power input will be less because the current through the LED is less (unless the dimming is done by shunting the LED, which would be a strange way of doing it unless there was some very good reason to). As you say though, the relationship between power and brightness won't necessarily be linear.
– nekomatic
2 hours ago
You are right, thanks for pointing it out @nekomatic
– Damien
1 hour ago
add a comment |Â
up vote
4
down vote
up vote
4
down vote
It depends on the LED driver, but unless it's of a bad (or very specific need) design, a dimmed LED lamp will draw less power.
Usually, dimming on LED lamps is done by PWM (Pulse Width Modulation). The LED will actually turn on and off faster than the eye can see. By modulating the ratio of the time the led is on and off, it simulates the dimming to the human eye.
This method is widely used because it is the cheapest and easiest method to dim an led but it can also cause some eye fatigue.
With this method the power will reduce with the light intensity (or perceived intensity).
Another method of controlling the light intensity of an LED is to control the current flow through the LED, and there are mostly 2 ways of doing it:
- Through DC/DC conversion like a current controlled buck converter or similar circuit.
in this case the current will reduce with the intensity of the LED. With this method, there will be little flicker, which will be roughly equivalent to the DC/DC converter ripple.
- Using an analog ballast (adjustable current source), like a transistor, mosfet or specialized IC with required regulation.
In this situation, the current will diminish but this circuit will likely have more losses.
The latest has the advantage of providing a very stable light intensity (if needed for some specific application perhaps like photography), so we can imagine this exists on the market.
The power will be reduced when the light intensity is reduced, but it's not a linear factor. F.I. 50% dimming might not have a 50% decrease on the power consumption.
The reason is that the control electronic will have some non-linearity and won't have the same efficiency at different operating condition and the second reason is that the eye intensity response is not linear to the actual light.
answered 3 hours ago
Damien
62517
It depends on the LED driver, but unless it's of a bad (or very specific need) design, a dimmed LED lamp will draw less power.
Usually, dimming on LED lamps is done by PWM (Pulse Width Modulation). The LED will actually turn on and off faster than the eye can see. By modulating the ratio of the time the led is on and off, it simulates the dimming to the human eye.
This method is widely used because it is the cheapest and easiest method to dim an led but it can also cause some eye fatigue.
With this method the power will reduce with the light intensity (or perceived intensity).
Another method of controlling the light intensity of an LED is to control the current flow through the LED, and there are mostly 2 ways of doing it:
- Through DC/DC conversion like a current controlled buck converter or similar circuit.
in this case the current will reduce with the intensity of the LED. With this method, there will be little flicker, which will be roughly equivalent to the DC/DC converter ripple.
- Using an analog ballast (adjustable current source), like a transistor, mosfet or specialized IC with required regulation.
In this situation, the current will diminish but this circuit will likely have more losses.
The latest has the advantage of providing a very stable light intensity (if needed for some specific application perhaps like photography), so we can imagine this exists on the market.
The power will be reduced when the light intensity is reduced, but it's not a linear factor. F.I. 50% dimming might not have a 50% decrease on the power consumption.
The reason is that the control electronic will have some non-linearity and won't have the same efficiency at different operating condition and the second reason is that the eye intensity response is not linear to the actual light.
answered 3 hours ago
Damien
62517
edited 1 hour ago
answered 3 hours ago
Damien
62517
answered 3 hours ago
Damien
62517
answered 3 hours ago
Damien
62517
62517
1
In this situation, the power that is not used for the led is dissipated by the ballast that controls the current, in that case, the power input will be the same even when dimmed. No, the power input will be less because the current through the LED is less (unless the dimming is done by shunting the LED, which would be a strange way of doing it unless there was some very good reason to). As you say though, the relationship between power and brightness won't necessarily be linear.
– nekomatic
2 hours ago
You are right, thanks for pointing it out @nekomatic
– Damien
1 hour ago
add a comment |Â
1
In this situation, the power that is not used for the led is dissipated by the ballast that controls the current, in that case, the power input will be the same even when dimmed. No, the power input will be less because the current through the LED is less (unless the dimming is done by shunting the LED, which would be a strange way of doing it unless there was some very good reason to). As you say though, the relationship between power and brightness won't necessarily be linear.
– nekomatic
2 hours ago
You are right, thanks for pointing it out @nekomatic
– Damien
1 hour ago
1
1
In this situation, the power that is not used for the led is dissipated by the ballast that controls the current, in that case, the power input will be the same even when dimmed. No, the power input will be less because the current through the LED is less (unless the dimming is done by shunting the LED, which would be a strange way of doing it unless there was some very good reason to). As you say though, the relationship between power and brightness won't necessarily be linear.
– nekomatic
2 hours ago
In this situation, the power that is not used for the led is dissipated by the ballast that controls the current, in that case, the power input will be the same even when dimmed. No, the power input will be less because the current through the LED is less (unless the dimming is done by shunting the LED, which would be a strange way of doing it unless there was some very good reason to). As you say though, the relationship between power and brightness won't necessarily be linear.
– nekomatic
2 hours ago
You are right, thanks for pointing it out @nekomatic
– Damien
1 hour ago
You are right, thanks for pointing it out @nekomatic
– Damien
1 hour ago
add a comment |Â
up vote
2
down vote
I will use about half (except for the controller using a bit).
Probably PWM is used, this means a duty cycle of 50%, means the light is on only half of the time, many times per second though.
answered 3 hours ago
Michel Keijzers
4,88262150
add a comment |Â
up vote
2
down vote
I will use about half (except for the controller using a bit).
Probably PWM is used, this means a duty cycle of 50%, means the light is on only half of the time, many times per second though.
answered 3 hours ago
Michel Keijzers
4,88262150
add a comment |Â
up vote
2
down vote
up vote
2
down vote
I will use about half (except for the controller using a bit).
Probably PWM is used, this means a duty cycle of 50%, means the light is on only half of the time, many times per second though.
answered 3 hours ago
Michel Keijzers
4,88262150
I will use about half (except for the controller using a bit).
Probably PWM is used, this means a duty cycle of 50%, means the light is on only half of the time, many times per second though.
answered 3 hours ago
Michel Keijzers
4,88262150
answered 3 hours ago
Michel Keijzers
4,88262150
answered 3 hours ago
Michel Keijzers
4,88262150
answered 3 hours ago
Michel Keijzers
4,88262150
4,88262150
add a comment |Â
add a comment |Â
up vote
2
down vote
In general yes, the LED itself will use less power when "dimmed". But we have to be a bit more specific what "dimmed" means.
So the answer depends a bit on how the dimming is done. If a pulse width modulation is used to control the LED's brightness, then the dissipated power scales directly with the pulswidth. This means full brightness is reached with max pulswidth what equals max power dissipation whereas as a reduced brightness requires less pulswidth and therefore dissipates less power.
Back in the days when light bulbs where used, dimming was done by so called phase angle control, comparable to something like AC pulse width modulation. And before that, you would just add a potentiometer as a pre-resistor. In that case, the bulb itself would dissipate less power when dimmed, but just because the resistor now burns the rest - so ovarall you had the same.
But long story short, when you use PWM, the power will scale with the pulse width. But consider that brightness doesn't scale linearly with dissipated power.
answered 3 hours ago
Humpawumpa
906113
add a comment |Â
up vote
2
down vote
In general yes, the LED itself will use less power when "dimmed". But we have to be a bit more specific what "dimmed" means.
So the answer depends a bit on how the dimming is done. If a pulse width modulation is used to control the LED's brightness, then the dissipated power scales directly with the pulswidth. This means full brightness is reached with max pulswidth what equals max power dissipation whereas as a reduced brightness requires less pulswidth and therefore dissipates less power.
Back in the days when light bulbs where used, dimming was done by so called phase angle control, comparable to something like AC pulse width modulation. And before that, you would just add a potentiometer as a pre-resistor. In that case, the bulb itself would dissipate less power when dimmed, but just because the resistor now burns the rest - so ovarall you had the same.
But long story short, when you use PWM, the power will scale with the pulse width. But consider that brightness doesn't scale linearly with dissipated power.
answered 3 hours ago
Humpawumpa
906113
add a comment |Â
up vote
2
down vote
up vote
2
down vote
In general yes, the LED itself will use less power when "dimmed". But we have to be a bit more specific what "dimmed" means.
So the answer depends a bit on how the dimming is done. If a pulse width modulation is used to control the LED's brightness, then the dissipated power scales directly with the pulswidth. This means full brightness is reached with max pulswidth what equals max power dissipation whereas as a reduced brightness requires less pulswidth and therefore dissipates less power.
Back in the days when light bulbs where used, dimming was done by so called phase angle control, comparable to something like AC pulse width modulation. And before that, you would just add a potentiometer as a pre-resistor. In that case, the bulb itself would dissipate less power when dimmed, but just because the resistor now burns the rest - so ovarall you had the same.
But long story short, when you use PWM, the power will scale with the pulse width. But consider that brightness doesn't scale linearly with dissipated power.
answered 3 hours ago
Humpawumpa
906113
In general yes, the LED itself will use less power when "dimmed". But we have to be a bit more specific what "dimmed" means.
So the answer depends a bit on how the dimming is done. If a pulse width modulation is used to control the LED's brightness, then the dissipated power scales directly with the pulswidth. This means full brightness is reached with max pulswidth what equals max power dissipation whereas as a reduced brightness requires less pulswidth and therefore dissipates less power.
Back in the days when light bulbs where used, dimming was done by so called phase angle control, comparable to something like AC pulse width modulation. And before that, you would just add a potentiometer as a pre-resistor. In that case, the bulb itself would dissipate less power when dimmed, but just because the resistor now burns the rest - so ovarall you had the same.
But long story short, when you use PWM, the power will scale with the pulse width. But consider that brightness doesn't scale linearly with dissipated power.
answered 3 hours ago
Humpawumpa
906113
edited 3 hours ago
answered 3 hours ago
Humpawumpa
906113
answered 3 hours ago
Humpawumpa
906113
answered 3 hours ago
Humpawumpa
906113
906113
add a comment |Â
add a comment |Â
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