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Should you care about LEDs usage?
Have you ever wondered if you should start using LED lights? And you’ve never found the time to find out if they’re really worth it. Let me show a couple of examples of the consequences of using LED bulbs or lights in your projects, home or even vehicles.
What a LED light really is
A light-emitting diode or LED, is a light source consisting of a semiconductor material with two terminals. It is a P-N junction diode, which emits light when activated. If a suitable voltage is applied to the terminals, electrons recombine with holes in the P-N junction region of the device, releasing energy in the form of photons. This effect is called electroluminescence, and the color of the light generated (which depends on the energy of the photons emitted) is determined by the bandgap of the semiconductor. LEDs are usually small (less than 1 mm²) and some optical components are associated with them to configure a radiation pattern.
So, we know from this technical description that a LED is just:
- a diode with two terminals
- that creates lights (fotons) when voltage applied.
- and color depends on wavelength
and common use diodes for DIY projects have following schematics
However, SMD leds have next schematics
SMD LEDs are currently the most used type of LED on the market. The large-scale production of manufacturers has reduced its price significantly and the development and continuous innovation in the luminescent part of the semiconductor crystals ensures that, year after year, LEDs offer more luminosity with the same power consumption.
SMD LEDs are currently the most used type of LED on the market. The large-scale production of large manufacturers has reduced their price significantly. The development and innovation in the luminescent part of the semiconductor crystals offer brighter SMD LEDs year after year, with a lower power consumption. Due to this, SMD LEDs are widely used in domestic and industrial lighting systems, in vehicles, as well as personal electronic devices such as LED screens, televisions, projectors, and so on. SMD LEDs with the RGB system are used for decorative lighting and big full color image screens.
Size dependant LED classification
Depending on their size, LED types are classified with a 4-digit number: the first 2 digits for the length and the next 2 for the LED height in tenths of a millimeter. For example, a 5050 led is 5x5mm. The following table shows the most commonly used SMD LED types.
| SMD LED module | Dimensions (mm x mm) | Power (watt) | Flux (lumen) | CRI (Ra) | Intensity (candela) | Beam angle (degree) | Heatsink (yes/no) | Efficacy (min) (lm/W) | Efficacy (max) (lm/W) | Colors per SMD Package |
|---|---|---|---|---|---|---|---|---|---|---|
| 8520 | 8.5 x 2.0 | 0.5 & 1 | 55–60 | 80 | 110 | 120 | Monochrome | |||
| 7020 | 7.0 x 2.0 | 0.5 & 1 | 40–55 | 75–85 | 80 | 110 | Monochrome | |||
| 7014 | 7.0 x 1.4 | 0.5 & 1 | 35–50 | 70–80 | 70 | 100 | Monochrome | |||
| 5736 | 5.7 x 3.6 | 0.5 | 40–55 | 80 | 15–18 | 120 | no | 80 | 110 | |
| 5733 | 5.7 x 3.3 | 0.5 | 35–50 | 80 | 15–18 | 120 | no | 70 | 100 | |
| 5730 | 5.7 x 3.0 | 0.5 | 30–45 | 75 | 15–18 | 120 | no | 60 | 90 | |
| 5630 | 5.6 x 3.0 | 0.5 | 30–45 | 70 | 18.4 | 120 | no | 60 | 90 | |
| 5060 | 5.0 x 6.0 | 0.2 | 26 | no | 130 | Mono OR RGB | ||||
| 5050 | 5.0 x 5.0 | 0.2 | 24 | no | 120 | Mono or RGB | ||||
| 4014 | 4.0 x 1.4 | 0.2 | 22–32 | 75–85 | 110 | 160 | ||||
| 3535 | 3.5 x 3.5 | 0.5 | 35–42 | 75–80 | 70 | 84 | ||||
| 3528 | 3.5 x 2.8 | 0.06–0.08 | 4–8 | 60–70 | 3 | 120 | no | 70 | 100 | |
| 3030 | 3.0 x 3.0 | 0.9 | 110–120 | 120 | 130 | |||||
| 3020 | 3.0 x 2.0 | 0.06 | 5.4 | 2.5 | 120 | no | 80 | 90 | ||
| 3014 | 3.0 x 1.4 | 0.1 | 9–12 | 75–85 | 2.1–3.5 | 120 | yes | 90 | 120 | |
| 2835 | 2.8 x 3.5 | 0.2 | 14–25 | 75–85 | 8.4–9.1 | 120 | yes | 70 | 125 | |
| 1206 | 1.2 x 0.6 | 3–6 | 55–60 | |||||||
| 1104 | 1.1 x 0.4 |
Current dependant LED classification
Depending on required current intensity, we classify them in 3 main areas: Low Current Intensity, Intermediate or Common Range and High Current Intensity
Low Current Intensity
Prepared for a current of 2mA with about 2V (consumption of about 4 mW).
Intermediate or Common Range
$20mA$ LEDs (between $40mW$ and $90mW$) around:
- 1.9 -2.1 V for red, orange yellow and traditional green.
- 3.0-3.4 V for pure green and blue.
- 2.9-4.2 V for violet, pink, purple and white.
High Current Intensity
For $20mA$ current and with 2 or 4-5 V, designed for viewing in direct sunlight. The 5 V and 12 V LEDs are normal miniature LEDs incorporating a series resistor for direct connection to a 5 or 12 V power supply.
Some real life examples
Let’s assume we have no idea which type of bulb is better, but we have the knowledge and tools to measure and take smart decisions. In following example, I show you how you can measure discover the operating current of a LED bulb and compare against others. Finally I will also make an estimation of a yearly cost of each of the options: LED light and halogen lamp.
For this example, I choose following two bulbs from Philips.
You can find them at Amazon
Some reference images of the products
| Component | Operating Voltage | Bulb type | Price on Amazon |
|---|---|---|---|
| LED LIGHT | 12V | W5W | 6 € |
| HALOGEN | 12V | W5W | 15 € |
There is no mathematical way to calculate the current consumtion, rather than measuring. To take measurements of the current drawn by each of the components we can easily connect an amperemeter or connect the device to be measured to a power supply that already contains one. For example, Im using following power supply
Measuring the current
In order to figure out how good the halogen bulb is, from comsumption point of view, we need to measure:
- Current over time
- Expected lifetime provided by manufacturer data
Measuring the current of each the halogen bulb
$P = I \cdot V$
where $V = 12$ and $I$ is the value we need to find out. So measuring the $I$ value we find that
$I = 0.35 \: A$
$P = 0.35 \cdot 12V = 4.2 \: W$
Measuring the current of each the led light
$P = I \cdot V$
where $V = 12$ and $I$ is the value we need to find out. So measuring the $I$ value we find that
$I = 0.04 \: A$
$P = 0.04 \cdot 12V = 0.48 \: W$
Comparing each of the results
Finally, we can compare both results, as shown below
| Component | Current (A) | Power (W) | Temperature | Price per year |
|---|---|---|---|---|
| LED LIGHT | 0.04 | 0.48 W | 80 ºC | 6 € |
| HALOGEN | 0.35 | 4.2 W | 20º C | 15 € |
The performance gain between both of them ($0.04A$ vs $0.35A$) is calculated then as $-88.57%$, meaning that LED techology helps you saving up to $88.57%$.
With an estimated energy cost of $0.3427 €/kWh$ and some math, we estime the yearly cost as:
$$12 \cdot 30 \cdot 24 = 8640 \: h/{year}$$ $$ P = I \cdot V = 0.04 \cdot 12 = 0.48 \: W/h$$
Making a somehow unrealistic usage estimation of consumption during a year as
$$W = 8640h/{year} \cdot 0.48 W/h = 4147.2 \: W/{year}$$
Finally, converting $W$ to ${Eur}$ we get
$$ {Cost} = 4147.2W/{year} \cdot 0.3427 €/{kWh} \cdot 1{kWh}/1000Wh $$
$$ {Cost} = 1,42124544 \: €/{year} $$
According to captured data, each hour you use a LED light with analyzed features it cost you around $0,000164496 \: €/h$
Conclusion
It is clearly proven that LED usage is better for both our projects, bulb lifetime and our budget, they tend to have better performance and help ous to save money. So, now you know it, use LED light at home, in your car, bike, cat…everywhere!
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