Marketing moves, tricks, defaults on the part of some manufacturers have led to the fact that many are still confused when buying. In this article we will try to tell as simply as possible how the LED lamp works and what you should look at when buying.
How much light does the LED lamp give
The first thing to deal with is the amount of light. The main confusion is associated with the habit of measuring the amount of light in watts, formed during the use of incandescent lamps. An incandescent lamp is a very simple object, it is a bulb inside which, in a vacuum, a tungsten filament of a certain length and diameter connects two contacts. As current flows, the filament heats up and glows – and the amount of light the bulb gives off is directly related to the current flowing, and therefore to the power consumption in watts. A 60 watt bulb will always give 40% less light than a 100 watt bulb, regardless of the manufacturer – same design, same materials.
With LED bulbs, which look so similar to incandescent bulbs, things are considerably more complicated. The most important thing is that the LED lamp – already quite a technically complex device, not two contacts connected by a filament. And, therefore, like any complex device, depends on how it is made, from engineering decisions and electronic stuffing. No one will not choose a TV or monitor, focusing on how much electricity it consumes – the power consumption can not say how good the picture will be on the screen. The same applies to LED lamps – by how many watts they consume, you can not clearly say how much light they give.
The amount of light objectively emitted by the lamp is measured not in watts, but in lumens.
For 1 watt consumed by an incandescent lamp, it gives 10 lumens of light.
| How many watts does it consume | How much light does |
| 100 watt | 1000 lumen |
| 60 watt | 600 lumen |
| 40 watt | 400 lumen |
With LED lamps, as has already been written, everything is a little more complicated. It is generally believed that per 1 watt of electricity consumed, the LED lamp produces 100 lumens – that is, 10 times more than an incandescent lamp. But this is an average, and in reality, the figures may differ. Look at the picture below, showing the packaging of a real LED bulb. There are two places circled in red in the picture that contain interesting information:
- This bulb consumes 8 watts. Remembering what was said about 100 lumens per watt, it is logical to assume that it should give 800 lumens, that is, as much as an incandescent bulb at 80 watts. However, under number 1, we see that the manufacturer’s marketers were more cautious in their estimation – they write “75W”.
- In reality, the situation is even more different: if you look at the number of lumens indicated under number 2, it turns out that this bulb gives 630 lumens, which is similar to a regular 63-watt bulb.
Example of consumption and light information in an LED bulb
That’s why we suggest not looking at the marketing information or consumption of the LED bulb, and immediately look for information on the packaging about the number of lumens. Found, divide by 10 – get a match with an incandescent bulb.
Bulb quality
Prices for LED lamps vary greatly. At well-known brands they are noticeably higher and often have to hear: “this is purely for the brand”. Not quite so. To understand the quality, let’s remember what was said above: the LED lamp is already a full-fledged electronic device. In the picture below, you can see what a traditional LED lamp consists of:
The design of the LED lamp
Without going into detail, let’s highlight two constituent parts to talk about the quality: 2, the LED board with crystals and 3, the power module.
The quality of the LED lamp is made up of several very significant parameters:
- Correctness and professionalism of engineering and materials. Here we are talking primarily about temperature. LEDs are very unhelpful to overheat – from this greatly reduces the life of their service life. So, a serious role is played by methods of heat dissipation and materials that conduct it well. In the manufacture of cheap lamps save on both the first and the second – as a result, LEDs are very overheated and fail much faster.
- Quality of electronics. Yes, the LED lamp has an electronic module – it converts the voltage from the network into the voltage required to power the LED (number 3 in the picture). It has several important points at once: the quality of the elements from which it is assembled, the quality of soldering, reliability and elaborateness of the circuit of the module itself. Simplified schemes and low-quality elements of the power module can lead to the following problems: increased heat separation (see item 1), rapid failure of the power module (and thus of the whole lamp – if the LEDs are still perfectly normal), rapid failure of LEDs in case of voltage spikes, which a low-quality power module “passes through” rather than filtering.
- Quality of LEDs. Modern LEDs are produced on the basis of crystals. Crystals are grown in factories in large batches and within one batch not all crystals are not the same – both in brightness and in their properties. One classic LED lamp contains several crystals (number 2 in the picture) and the properties of each of them may differ slightly. In expensive lamps, the crystals are chosen carefully, so that the difference between them was minimal or that they are completely identical. In cheap lamps, the crystals may differ greatly from each other, which means that the light of the whole lamp in the end may not be exactly as stated.
What light parameters suffer in cheap lamps due to crystal differences:
– The amount of light. The amount of light indicated even in lumens is not the amount of light that gives this particular lamp, it is the average amount of light per batch. If the LED crystals have not been selected very carefully, the amount of light a particular lamp may differ from the average;
– Color rendering index. Color rendering index, CRI, is a criterion that shows how close the light of an LED lamp is to the composition of the sun and how much all objects in the room with such a lamp will look as if in natural daylight. Its value is measured in percent, 100 – this is a complete match (almost impossible), usually the lamps have numbers less, it is best to take with values of 80 or more. But this is also the average value of the batch, and if the lamp is cheap, not a very well-known manufacturer, then a particular lamp this property can also “dance”, which means that the light in the room may be slightly bluish, greenish, etc.
– Loss of brightness. Interesting fact – the LEDs themselves, even not very high quality, as a rule, are able to work much longer than its manufacturer’s stated life. If there is no overheating and power surges, if the power module does not fail, they will work much longer than the stated 20 – 25 years. But every year any LED will lose a little in brightness, this is called degeneration. For good LEDs the loss will be minimal, for lesser quality LEDs the process will go much faster. Thus, there is a significant probability that both cheap and quality lamp will work their 20 years, but the good during this time the loss of brightness will be 20% or less, and the cheap – 50% or more. Such a drop in illumination, especially unnoticeable due to the length of time, can be very damaging to health – you will not immediately notice that the amount of light is greatly reduced. - Flicker. An effect also known to many, and sometimes erroneously attributed to LEDs. In fact, the LEDs themselves do not flicker – the flicker is caused by an oversimplified power module circuit. In fact, this problem is related to point 2, already discussed above, but because of its relevance, we have separated it into a separate point. Over-simplified circuit, poor quality soldering and cheap components of the boards marked in the figure with numbers 2 and 3 lead to flickering of the lamp light, which is very unhelpful.
Conclusion – “brand markup” certainly exists, but most of it is formed by the cost of qualified engineering staff, quality control department and the use of quality materials and components. It is not necessary to save extremely on this.
Types of LED lamps
Today there are two main types of LED lamps: traditional LED lamps, the device of which we analyzed above, and filament lamps, which originally appeared as decorative to replace the “Edison lamps”, but now, with the development of technology is likely to replace the traditional.
The difference between the two can be easily seen in the picture below:
Filament lamps, as the name suggests, are not based on a board with several crystals (LEDs), but on the combination of micro-LED crystals into a luminous filament (from the outside we see not the crystals themselves, but the phosphor surrounding them).
The advantages of filament lamps are obvious – it is a complete match to the appearance of the classic incandescent lamp, and the absence of a white matte diffuser, which does not look very good, and the spread of light almost 360 degrees around itself – like an incandescent lamp. Moreover, the design of LED filaments is such that filament lamps are much less prone to flicker, so with the smaller size of the power module, completely inside the base, it is still quite possible to create a compact power module with a flicker rate of less than 1%.
Filament lamps have one disadvantage, and it also follows from the design: overheating of the LED modules. Since the modules are on a filament that is no longer in contact with any surface, it is impossible to properly dissipate heat from the LEDs. According to research, the LED modules on the filament always operate at a temperature higher than comfortable for the LEDs. It is believed that the temperature of the LED should not exceed 80 degrees Celsius. In traditional lamps, modules on an aluminum substrate operate at 60-70 degrees, while filament lamps most often operate at 90-100 degrees. The result is clear – faster degeneration (loss of brightness and color rendering index), as we wrote above.
Not so long ago, when the cost of filament lamps was quite high, this would have played a significant role in the choice. But today it is no longer so critical – traditional LED lamps and filament lamps cost about the same and choose what is more important to you – a couple of extra years of work or the lack of ripple and design of the classic incandescent lamp – can already be to your own taste.
