LED brightness question

[gyaani]

Hi
I am from India, in this UK forum, because I this is really the first active DIY forum I could find outside reddit . I hope this is okay

I want to replace a LED tubelight in my room 3mx4m with a LED strip, that I can shape around and get a similar light output.
LED is a 20W philips tubelight.

But it seems a Philips 18W LED tube-light is much brighter than a equal or higher wattage LED strip. Is this true ?
If so that could be either due to poor quality led strips ? or maybe by not supplying enough power..

Second the lumen calculations seem off. This item 10m led strip - total 720 smd 3014 bulbs. According to wikipedia that's 10lumen/bulb. This would mean its 7000 lumens!! 3 times bright than my tubelight . But the pictures and comments make it seem so much dimmer.

Product: https://www.amazon.in/Murphy-3014-72-Waterproof-Strip-Light/dp/B09HWQZZN2/

 

[flameport]

Not clear what the light output or power consumption of that strip is, however a typical LED strip would be in the 10 or 12 watts per metre length. 5m lengths of 12 or 24 volts strips are often run from a 60W power supply, so would be about 100 or 120 watts for a 10m length.
For 7000 lumens, that would be a fairly modest 70 lumens/watt for the LEDs which is certainly possible.

In terms of lumens per watt, LEDs are not significantly better than fluorescent, however they are far more directional so can appear brighter in some types of light fitting.
Tube types are one of those, as the LED versions have 100% of the light coming out of one side, compared to the fluorescent which outputs light in all directions.

A typical 10m LED strip will be far brighter than a 20W fluorescent tube, but will also use a lot more power, in the region of 100-120 watts.

 

[ericmark]

It all depends on the driver, a LED is a current dependent device, so some where in the circuit there needs to be some thing to limit the current, this could be a simple resistor, or a capacitor, or a switched mode power supply (SMPS) also called a pulse width modulated (PWM) unit so the efficiency of the whole lamp is very much dependent on the method used to drive the LED's.

So the strip light I bought from our discount shop called Lidi, is colour changing and dimming and to do this it uses a PWM unit so a 2 meter strip is rated 22 watt it does not state lumen but it is high, uses zigbee control, but most of the coils of LED lights are for decoration not lighting, the Lidi one I have is unusual to give out so much light.

 

[gyaani]

hmm, so a LED strip run from a proper LED driver could be much brighter than something running of a DC adapter ?

the coils of LED lights are for decoration

What are 'coils of LED lights' ? Something other than the bulb or the power supply ?

Tube types are one of those, as the LED versions have 100% of the light coming out of one side, compared to the fluorescent which outputs light in all directions.

The LED tube I have has a really good diffusion layer, spreads out light perfectly, as good as the old fluorescent tubes. But I am not comparing with fluorescent tubes, but led Tubes with led strips.

Basically, a LED strip having 5050 SMD which is 24 lumen/bulb (https://en.wikipedia.org/wiki/SMD_LED) , should have 2000+ L in a 90 led 1 meter strip ? BUT the photos, videos and comments suggest that its not bright !

Another one: this is 70W 5050 led strip. So is it reasonable to assume it would be 3 times as bright as a single 20W LED tubelight ? lets assume a good LED driver is used.. https://www.amazon.in/Protium-Light...id=1655999582&sprefix=led+505,aps,295&sr=8-29

 

[bernardgreen]

To get the best illumination use a basic LED strip such as this type. ....

The current through the individual LED elements is determined by the supply voltage and the series resistor, Therefore it requires a DC power source and NOT an LED driver,

 

[ericmark]

The diagram @bernardgreen shows uses a resistor as the driver, so a white LED has a volt drop across it of approx 3 volt, so 9 volt used to light, and 3 volt used to heat, so if the LED chip gives out 100 lumen per watt, as a whole it gives out 75 lumen per watt.

The resistor changes the package from a current dependent device to a voltage dependent package. WIth an AC supply we can use a capacitor instead of a resistor, but we still need a leak resistor to sink any voltage raised with capacitive or inductive linking, and a rectifier.

So the bigger the package and higher the voltage the less loses and use a pulse width regulator and it can correct any voltage variation as well.

So if you light a room with 16 down lights you will need more wattage than a single tube, and if you use 40 smaller units in a strip light then again you need even more watts.

In the UK lights need to say there linen output, decorations don't so if no lumen output is listed then designed for decoration. Proper lights will have lumen output and will be rated A++, A+, A, B etc.

 

[bernardgreen]

The diagram @bernardgreen shows uses a resistor as the driver,

The resistor is NOT a driver, it is a current limiting device,

A driver forces a current through the lights. It measures the current and automatically adjusts it's output voltage to be the voltage needed to drive the rated current through the LED elements

so a white LED has a volt drop across it of approx 3 volt

For example a 100 mA driver supplying 10 white LED elements will set its output to be 30 volts
The same driver supplying 16 LED elements will set its output to be 48 volts

If a driver is used to supply a 12 volt LED tape where the current is controlled by a resistor then the driver will increase its output voltage to try and force the 100 mA through the LED elements and the resistor.
,

 

[RandomGrinch]

Therefore it requires a DC power source and NOT an LED driver

This is one of those terms that may be technically absolutely correct - however, in everyday use, whether it be constant current, or constant voltage - the common term for an LED power supply is a 'driver'!

 

[bernardgreen]

the common term for an LED power supply is a 'driver'!

Which results in the un-formed DIYer ( and some "professionals " ) connecting a driver ( current forcing ) to a lamp and the LED elements in the lamp being destroyed by too much current being forced through them

Calling a Dyson vacuum cleaner a Hoover is very common but is not creating a hazard, Hoovers and Dysons both do the same thing, They such up dirt,

Power supplies ( constant voltage output ) are not the same as LED drivers ( constant current output ) ,

This is a forum giving advice The advice given should be technically absolutely correct and use the correct terms for what are two very different items

 

[RandomGrinch]

Which results in the un-formed DIYer ( and some "professionals " ) connecting a driver ( current forcing ) to a lamp and the LED elements in the lamp being destroyed by too much current being forced through them

I think your argument may be overstated
As the 'un-informed' may not know the technical difference between a power supply and a current driver, and the trade in general call both c.c. and c.v. supplies 'drivers', (example here:
https://uk.rs-online.com/web/generalDisplay.html?id=ideas-and-advice/led-drivers-guide )
a diy-er would be as likely to choose the wrong supply (with potentially damaging consequences) whether they knew the difference, or not!

 

[ericmark]

The point is an LED is a current dependent device, so supplying a fixed voltage will not work, so some where some how some thing needs to be done to limit the current to stop a thermal run away, in the main the device used to stop the thermal run away is called a driver, a single term to cover all methods used, as @RandomGrinch says the constant voltage power supply is often called a driver, where really it should be called a DC power supply designed for lights.

However it is the control of the current which changes the same LED chip from giving 100 lumens per watt to 60 lumens per watt, I have the boxes on my desk for two GU10 bulbs, one is a smart bulb with an input of 5.5 watt and output of 345 lumen and can only change the colour temperature, the other also a smart bulb an input of 5 watt and output of 500 lumen this was can also change colour red, green, blue etc. I had one of the latter bulbs fail and so could open it, a look inside and clearly a lot of control stuff there.

My Smart LED light strip from Lidi does have a high output, I have one under the kitchen cupboards to light the counter top, and I have to turn it down to minimum output, it is rated at 22 watt for a 2 meter strip, no lumen output is given. But it is high. However with no lumen output it is clearly for decoration.

Calling a Dyson vacuum cleaner a Hoover is very common

Yes and clearly wrong, the cleaner does not produce a vacuum, it uses air volatility, however walk into a shop and ask for an air volatility cleaner and you get a blank look, call it a vacuum, Dyson or Hoover and they know what you mean.

It does not matter if it is driver, transformer, ballast, it seems the lighting industry calls things after what they replaced, even the electricity supply company use kWh for energy measurements where is should be in Joules. We still see school children being taught using the centimetre, a non ISO unit they don't exist, but we can use anything as a yard stick to help us, even if the yard stick is actually a meter long.

The km should be same as nautical mile, but the French made a mistake as to size of the earth. But does it really matter, it is defined as so many wave lengths of a set colour of light, orange I seem to remember, where the nautical mile is a minute around the earth, so there is no way there can be a translation between the two, as an aircraft will travel more km to a ship going from same place to same place but same amount of nautical miles. But google it and it says 1 km = 0.539957 nautical miles. Nothing about at sea level etc.

So "Basically, a LED strip having 5050 SMD which is 24 lumen/bulb" can be driven to the limit, or it can be set to allow for over voltage, a typical 12 volt battery on charge is between 13.4 and 14.4 volt, but called 12 volt. A LED "driver" voltage regulated is typically 11.8 volt but again called 12 volt. We see the Dubai lamp grossly under driven to give a long life.

This firm specialises in bulbs for narrow boats and caravans, the main thing is they can work on any voltage between 10 - 30, and give a good lumen per watt, they are expensive, but with a narrow boat of caravan you have a variable voltage depending on if engine running, or shore supply or just battery, and you don't want to waste energy, so worth the extra money. But in my house the difference in price for a bulb giving 62 lumen per watt and 100 lumen per watt means I will accept one giving 62 lumen per watt, what seems odd, both are rated at A+ one wonders what is the point when there is such a huge difference.

 

[bernardgreen]

air volatility ?

1. 1.
   liability to change rapidly and unpredictably, especially for the worse.
   "the succession of new rulers contributed to the volatility of the situation"
   • 
     
2. 2.
   tendency of a substance to evaporate at normal temperatures.
   "the volatility of chemicals in an indoor environment"

 

[winston1]

Calling a Dyson vacuum cleaner a Hoover is very common but is not creating a hazard, Hoovers and Dysons both do the same thing, They such up dirt,

Sometimes. Some Hoovers wash clothes or dishes. I don't think Dysons do.

Some Dysons blow dry hair, do any Hoovers?

Using correct terms is important to avoid confusion and danger.

 

[bernardgreen]

a diy-er would be as likely to choose the wrong supply (with potentially damaging consequences) whether they knew the difference, or not!

So if this forum can provide information about the difference the number of burnt out LED elements might be reduced

 

[bernardgreen]

I don't think Dysons do.

Dyson CR1 washing machine,