Connect the LED to 12 volts. Which LED connection scheme is better - serial or parallel?

Connecting an LED to a 12V power source can be done in several ways. The first option for solving the problem is to increase the series-connected LEDs in the circuit. The second method involves the use of a current-limiting resistor.

Let's consider both methods.

Calculation of a resistor using the example of one LED

Most LEDs have a forward voltage drop with a current allowance of 1.8 - 3.6 V. Therefore, to connect to a 12 V source, we need to reduce the voltage across the LED, otherwise it will burn out. This is done using a current limiting resistor. With the correct resistance the LED will work properly. To find out where is the cathode and where is the anode of the LED, read this.

Let's assume that we have a white LED whose parameters are as follows:

The resistor is calculated according to the following formula:

where Up is the supply voltage, Usv is the forward voltage drop across the LED, and I is the LED current, 0.75 is the LED reliability factor.

If the LED current is unknown, but its power is known, the formula takes the form:

In our case, the LED current is known.

Based on our calculations, we need the closest rated resistor at 620 Ohms. If the calculated resistance turns out to be such that it will be difficult to select a resistor, then it makes sense to use several parallel-connected resistors.

To prevent the resistor from burning out, it is necessary to select it correctly in terms of power. To do this, let's calculate the power allocated to the resistor.

Then we calculate the total current in the circuit taking into account the added resistance of the resistor:

We substitute the resulting value into the DC power formula:

We conclude that we need a resistor designed for at least 0,25 Watts of power. If you do not have such a resistor on hand, you can get out of the situation by using two resistors of 0.125 W each connected in parallel, or simply by increasing the resistor value by 15-20% (in this case this is possible, but the brightness of the LED will decrease).

Connecting 3 LEDs to 12 V

Connecting three LEDs to a 12 V power source allows you to use a resistor with less power, since the total voltage drop across the three LEDs will be 3 times greater.

Let's say we have a yellow LED with the following parameters:

Let's calculate the resistance of the ballast resistor using the already known formula:

The nearest resistor suitable for a nominal value of 510 Ohms will determine the required power

Calculate the LED resistance:

The total current in the circuit, taking into account the added resistance of the resistor:

We substitute the resulting value into the DC power formula.

Energy-saving technologies and equipment are in demand and popular. One such device is an LED lamp. It uses LEDs as a light source, which are combined into one circuit. This light bulb is used in lighting fixtures to decorate the illumination of buildings and structures, in spotlights that are mounted on suspended or suspended ceiling structures.

Design of LED lamps

LED lamps are designed for a voltage of 12 V and, accordingly, the design of the device differs from its fluorescent counterparts or those that use an incandescent filament. Structurally, it is made of the following main components:

• Glass flask. It can be made of transparent or frosted glass and have a spherical or flat shape. The dome design increases the light dispersion angle to 270°. Models of light bulbs with a flat glass surface are used in spotlights to illuminate the interior or divide the area into separate zones. Lighting angle 30 – 60°.
• LEDs. Light sources are connected in series into one connection circuit, which increases the light output of the device.
• Radiator. It is a metal plate made of aluminum alloy. It is designed to remove the heat emitted by the LEDs.
• Frame. It is made of high-strength plastic, which is a dielectric and performs protective functions against electric shock when installing or dismantling the light source.
• Driver. Designed to stabilize voltage and convert current from alternating to direct.
• Base. It can be manufactured for different types of cartridges: standard design E27 and E14 or G4, G13, GU10 and so on.

Depending on the amount of light emitted by one diode and the number, the brightness of the LED lamp is determined. The average illumination value is calculated from the ratio of 1 Lm (Lumen - a unit of measurement of the brightness of a luminous flux) per 100 W.

Advantages and disadvantages of 12V lighting

To switch to lighting fixtures that connect to a low-voltage power source, you should study their advantages and disadvantages. Among the advantages are the following:

• Safety. The use of LED lamps in 12V luminaires increases the level of protection and eliminates the possibility of electric shock.
• Fire safety. Low voltage wiring cannot be a source of ignition or cause a fire. Therefore, the wires do not need additional protection; they are not placed in corrugated sleeves.
• Versatility. An electric current whose voltage does not exceed 12 V is considered conditionally safe and cannot cause serious harm to a person. In this regard, these lamps can be used in rooms with normal conditions and increased danger. For example, in lamps for a sauna, cellar, bathroom, kitchen, bedroom, etc.
• Saving. When using this light source to illuminate a room, it reduces energy consumption and, accordingly, the cost of money to pay bills.
• Environmental friendliness. The design does not use materials that, during operation of the device, emit substances harmful to human or animal health.
• Reliability. The lamps are highly resistant to mechanical damage: scratches, chips, dents, etc.

Despite all the advantages, the light source also has its disadvantages. The disadvantages of LED lamps designed for 12V include:

• An additional device is required - a power supply unit (PSU). The presence of a driver that stabilizes and reduces the network voltage from 220 to 12 V complicates the wiring. It has its own efficiency, which reduces the efficiency of lighting and due to it, an additional weak link appears in the circuit, which can fail.
• Glow brightness. The luminous flux power of a lamp connected to a low-voltage network is affected by the voltage drop. This occurs due to high current consumption. Therefore, the length of the conductor from the transformer to the first and last light source must be the same, an error of 2 - 3% is allowed. Otherwise, the last lamp will shine dimmer than the first.

Types of LED lamps

Light sources are classified according to several criteria:

• Base type. Available in traditional versions with standard sizes: E14, E27, E40. Baseless lamp models are also produced: G4, G5, G9, etc.
• Glow temperature. There are three types of emitted light: soft - temperature from 2500 to 2700 °K, white - 3800 - 4500 °K and cold light temperature more than 5000 °K
• LED type. Depending on the power and purpose of the lamp, LEDs have different configurations, which are determined by the type of crystal. It can have legs for connection or be mounted directly into the board.

Power supply for 12V LED lamps

Power supplies are selected depending on the purpose of the LED lamps.

They are divided into the following types:

• Sealed. Used for installing lamps in the bathroom, sauna, and street lighting.
• Leaky. Designed for indoor installation with normal humidity levels.
• With active cooling. It is equipped with a fan, which increases power and reduces size.
• Passive cooling. A radiator is used to remove heat. The advantage is silent operation. Disadvantage: power is limited by the size of the device.

Also, power supplies are selected according to their main characteristics:

• Power. It is calculated by adding the entire connected load plus a power reserve of 10 - 15% to prevent operation in overload mode.
• Output current. Depends on the number of connected lamps. If the load power and the “cosine phi” of the lamps are known, then the current can be calculated using the formula: total power of the lamps / 12 / cos φ. The value of the parameter also determines the cross-sectional area of ​​the conductors connecting the power supply and lamps.
• Output voltage. For our case it is 12V.

When connecting 12V LED lamps to a 220V electrical line, they must be powered by a driver or power supply.

Technical progress in the field of energy-saving technologies contributes to the constant development and improvement of the technical and operational characteristics of LED lamps.

Video on the topic

12 volt LEDs for cars have 11 main advantages, which it will be useful for you to know about, they are gradually replacing old light bulbs from everyday use, even in cars, drivers are trying to install LED backlighting. Today it is widely used for:

• car interior lighting;
• dashboard lighting;
• trunk lighting
• replacing conventional light bulbs installed in headlights

Selection diagram for LED lamps for a car

The demand for LEDs is quite justified, because they have many advantages over incandescent lamps and mercury lamps.

12 volt LEDs for cars: their advantages and efficiency

1. Economical energy consumption. LED lamps consume 70% less electricity than incandescent lamps.
2. LEDs do not burn out, so they do not have to be replaced even after a long period of use.
3. They do not require special conditions for disposal, because LEDs are not hazardous to the environment, unlike mercury lamps.
4. The brightness of the lighting remains constant, regardless of the service life of the lamps.
5. LED lamps are very durable. They are made of aluminum and polycarbonate glass that can withstand heavy impact loads.
6. LEDs provide good illumination. With this light, all objects and their colors are clearly visible. 12 volt LEDs for cars are ideal for low beam.
7. LEDs turn on instantly and can operate at any ambient temperature.
8. LED lighting does not cause eye fatigue because it does not have a low-frequency ripple effect.
9. Powerful flashlights made from LEDs do not dazzle your eyes.
10. They heat up less, so they will not damage the optics in the car.

• LED devices produce brighter light when compared to incandescent light. Therefore, your car with LED headlights will be more visible on the track. 12 volt car LED bulbs are widely used in fog lights. A strobe light with LEDs will help make your car more visible on the road at any time of the day. An alarm with a bright LED will scare away burglars.

Ultra-bright automotive LED lamps - design features

The design of LED light bulbs with E27 base can be seen in Figure 1

Types of LEDs that are used in cars

To obtain the required lighting brightness in different parts of the car, the following types of LED lamps are used:

• The H1 base is used in the front high beam headlights. Truck drivers often use 24-volt LED car lamps, which successfully replace xenon lamps;
• To make the low beam lights brighter, install H4 and H7 lamps.
• in the trunk and interior they use C5W, W5W, BA9S;

• rear license plate or instrument panel illumination is mounted using T5 lamps;
• For fog lights, lamps H1, H3, HB3, HB2, H4, H7, H11 are suitable. 12 volt automotive LEDs are used more often than others. A 12 volt LED lamp powered by a battery can also be used for low beam lighting.
• BA15S lamps are suitable for turning signals. This type of LEDs corresponds to P21W.
• For tail lights, BAY15D is installed. In European cars, this type of two-pin LEDs is designated P21/5W.

Popular 12 volt LED lamps. Manufacturers and their price categories

Among all purchased LED lamps for cars, the leading products are from the following companies:

• KARKAM Electronics. The company produces LED lamps for automotive lighting based on CREE LEDs. A set of two H4 lamps will cost 2990 rubles. 12 volt LEDs for cars from this company are often used in fog lights.
• OSRAM. OSRAM LED products are manufactured with precise adherence to technology, with careful quality control of raw materials at all stages of the process and at each of the OSRAM factories located around the world. The price of Osram P21W LEDriving Premium is about 1200 rubles.
• Philips Automotive. The company is a world leader in the production of LED light bulbs. The Philips X-treme Ultinon LED H4 lamp will cost RUB 3,847. Common
  LEDs for a 12 volt car from Philips will cost 600-700 rubles. Popular hb4 LEDs can be purchased for approximately 4,000 rubles.
• Lighthouse. The H11 lamp from the famous Russian company will cost 500 rubles.

24 volt LEDs for cars (China) are also in demand on the market due to their low cost. LED lamps for a 24 volt car can be bought for an average of 1000 rubles.

Installation features and connection diagrams. Why can't LEDs be directly connected to the car's network?

The voltage in the car's electrical network ranges from 12.5 volts to 14.5 volts, and the operating voltage of the LED is about 3 volts, so they cannot be directly connected to the on-board network. Before connecting each element to the battery, you need to determine the polarity of the LED. The negative is connected to the cathode of the LED, and the positive is connected to a direct current source. It is impossible to connect LEDs to 12 volts of a car without a resistor.

To create the backlight, ready-made tapes are used. They are made from several LEDs and resistors. Each such cluster is designed for a specific voltage.

If the electrical parameters meet those acceptable for your vehicle, then installation can begin. If necessary, LED strips can be divided into parts. This must be done according to the markings provided by the manufacturer so as not to damage the electrical circuit.

How to assemble a LED circuit yourself. Why do you need a voltage stabilizer and resistor?

A circuit of three white LEDs with a voltage of 3.5 volts and a resistor is easy to assemble with your own hands. All light bulbs are connected in series, and the difference with the voltage of the car electrical network is compensated using a 100 Ohm resistor and a power of 0.5 Watts. It is also connected in series in the circuit. Several chains can be assembled and connected in parallel so that all sections have the same voltage drop. The light bulbs are assembled on foil PCB.

A voltage stabilizer connected to the circuit will help prevent the headlights from dimming the moment the car starts moving.

To complete the assembly you will need plastic clamps and a soldering iron. If you can solder professionally and understand the electrical wiring of your vehicle, then you can safely get to work. If you do not have such knowledge, then it is better to entrust the work to professionals so as not to risk your car. They will do this work quickly and efficiently. Below is a video with a test of 12 volt LEDs.

12 volts are a relatively new lighting source that has become widely used not so long ago. Our compatriots choose diodes because of their aesthetic beauty, as well as a longer service life. For more information on how diode elements are connected and what needs to be taken into account, read below.

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What does a car owner need to consider before replacing?

In order to correctly connect LED light bulbs with your own hands, using a connection diagram, you first need to understand the basic information. First you need to understand that a 12-volt blinking car diode is not a lamp.

Connecting LEDs to a 12-volt on-board network should be done taking into account some points:

1. First of all, to secure the connection, you need to take into account the voltage that is present in the car electrical network. As a rule, this parameter is about 12-13 volts when the engine is off and about 13-14.5 volts when the engine is running.
2. On average, one bright and powerful diode requires 3.5 volts of power, but this figure can also vary depending on the color. For example, a yellow or red flashing LED for a car will consume about 2.3 volts, and white or blue elements will consume 3.5 volts on average.
3. Unlike standard incandescent light bulbs, LED assemblies provide better illumination of the surrounding surface, which is especially good for installation in dashboards.
4. Before purchasing, you should check the type of lens installed in the light bulb. There are highly targeted devices equipped with small lenses.
5. Regardless of the type, twelve-volt diode elements have both a positive and negative terminal. The positive contact in this case is the anode, and the negative contact is the cathode.

To choose the right 12V diode elements, you need to navigate their varieties, and they are divided among themselves by power:

1. Low-power devices do not have a cooling system, so their service life is usually short. In cars, it makes sense to use such devices only as indicators, for example, when turning on daytime running lights or when installing a battery discharge controller.
2. Powerful 12V diodes have a longer service life; if used correctly, they can last up to 10 years. It must be taken into account that such diode elements are not subject to heavy loads.
3. Modules Such devices are a steel plate on which a number of diode elements are mounted. The price of a module depends on its reliability and production quality - the better the quality, the higher the price. The modules should not be confused with Chinese tapes, since their operation is possible, perhaps, to illuminate the control panel or glove compartment.

Instructions for connecting LEDs

How to connect an LED to your car? What resistance should be selected for the LED? Do I need to use resistors?

Below we will describe how the diode module should be connected:

1. The procedure for connecting LEDs to a 12-volt network begins with calculating the power supply. The main disadvantage of clusters is that their brightness will depend on changes in engine speed. If the rpm drops, the power will also decrease. Consider the fact that the most optimal indicator for a good glow of clusters is the voltage parameter of 12.5 volts - if it is lower, the glow will be weak.
2. The cluster design includes diode elements and a resistor, which, by the way, is an important component of any cluster. The resistor device used to absorb excess voltage is installed at the rate of one per three diode elements. So if you bought a whole strip to install in an optic, you will most likely need to cut it. Moreover, circumcision should be carried out only on certain segments.
3. The connection procedure is carried out in a sequential manner. That is, you will need to first make a cluster by connecting several diodes to each other in turn, and the ends of the cluster are connected to the on-board network. As an example, consider white diode components with a power of 3.5 volts. For a regular 12 V on-board network, you will need three diode bulbs, which will consume a total of 10.5 volts. Daisy chaining means that the positive terminal of one component must be connected to the negative terminal of another.
4. There is no need to directly connect the cluster yet; a resistance, that is, a resistor, is connected in series. It should be taken into account that the resistance should be about 100-150 Ohms, and the resistor power parameter should be 0.5 W (the author of the video is the Auto Repair and Tuning channel).

Parallel connection method

To connect an LED to 12 volts in parallel, follow these steps (an example is considered with a 3.5 volt diode element and a current of 20 mA):

1. Measure the voltage where the light source will be connected to ensure that the connection will be effective. For example, this is 13 volts.
2. After this, 3.5 volts of the diode are subtracted from 13 volts, resulting in 9.5 volts. All measurements are made using Ohm's formula - in our case, 20 mA is divided by 100, resulting in 0.02 A.
3. The same formula is used to calculate the resistance; to do this, 9.5 volts must be divided by 0.02. As a result, we find out that we need a 475 Ohm resistor.
4. The next step is to calculate the power - you need to know this in order to prevent overheating of the resistor element. According to our parameters, 9.5 is multiplied by 0.02 - we get 0.19 W. To prevent possible failures, power can be taken in reserve.
5. Next, using a multimeter, the current is measured in the area between the diode lighting source and the resistor element. After this, the tester is set to 10 amperes, and the positive terminal of the device must be connected to the battery positive, the negative terminal to the lamp positive.
6. Ultimately, a reading of around 20 mA should appear on the multimeter display. Depending on the light source, as well as the resistance used, the parameters may differ.

Photo gallery “Diode connection diagrams”

Conclusion

What you need to consider for the system to work correctly:

1. To prevent the brightness of light sources from changing, you can additionally add a stabilizer to the circuit.
2. When connecting, you need to use high-quality resistance, since the efficiency of the backlight depends on the resistor. In addition, if you do not want to regularly change diodes, then they must also be of high quality.
3. If you are not sure that you can connect the backlight correctly, it is better to seek help from an electrician.
4. Before connecting, be sure to check the voltage in the on-board network - if it is low, then you need to check the functionality of the battery and generator.

Price issue

The cost of diodes differs depending on their type and purpose. For example, for one headlight lamp the car owner will have to pay from 300 to 5 thousand rubles. Conventional diodes for installation in the dashboard cost about 75 kopecks apiece. A piece of diode strip 30 cm long will cost about 600 rubles.

Video “Features of connecting diode lamps in cars”

What needs to be taken into account and what mistakes should not be made - recommendations from a specialist in connecting diode lighting sources are given in the video below (author - Amateur Radio channel).

After the article about many questions from visitors disappeared. But another question arose - in particular: connecting LEDs to 12 V. For the most part, car enthusiasts are interested in this.

I want to make a diagram. which will allow you to power 1-3 LEDs in parallel from 12 V. Using one of the online calculators, I calculated that I need 2 resistors - 100 and 33 Ohms. After assembling the 100 ohm circuit, the resistor overheats and fails. What needs to be done to prevent the resistor from overheating? Both resistors are 1/2 W. LEDs 3.6 V. Andrey P.

Of the many questions, I chose one, the most interesting. And I’ll try to explain in a more popular way the process of connecting LEDs to 12 V.

Connecting LEDs to 12 V using a simple scheme

This scheme is not suitable for our purposes; there will be no division in the proportion of 1 to 4.

We need to either use three LEDs connected in series with one resistor, or if you still want a parallel connection, then a resistor must be installed at each LED.

In my case, I would take a resistance of 20 mA. This is the most optimal solution. In general, resistors need to be selected based on a specific type of LED.

Connecting LEDs to a car battery from 9-12-16V

The connection diagram discussed above is very simple and assumes that you have 12 V DC.

Earlier, I already made a reservation that most questions are asked by car enthusiasts, and this of course implies connecting any LEDs to the car battery. Most batteries operate at a nominal 12V, but battery voltage varies from 9V to 16V during operation.

Let's take a simple example - the voltage drop across the LED is about 3.5 V at a current of 100 mA. therefore we have a power of 0.35 W (Power = Current x Voltage).

For an LED this will not play a big role, because we still have 12.5 V, which we can use somewhere else, using, of course, a resistor: (16V - 3.5 V) * 100 mA = 1.25 W.

Nominal battery voltage 12 V

Nominal Calcluations (i.e. Vbattery = 12V):

Pled = 3.5 V * 100 mA = 0.35 W (same as before)

Presistor = 8.5V * 100mA = 0.85W

To avoid excessive voltage drop across the resistor, you can use the circuit (shown in the first part of the article). However, it is worth remembering that if the battery is discharged and close to 12 V, then the likelihood is high that your LEDs connected to 12 V simply will not light up.

3.5V + 3.5V + 3.5V + Current*Rresistor = pretty close to 12V.

Connecting LEDs to 12 V using two resistors

You can connect LEDs to 12 V using not one but two resistors. The scheme is not much more complicated, but it is safer and “more efficient”.

A bipolar transistor is connected in each line. In the first line we see that the base is shorted to the collector and emitter and to ground. All bases are connected to each other. As a result, the same current will flow through each line. It is not possible to guarantee one hundred percent performance, since temperature conditions can play a big role.

I'll repeat it again. that this scheme is “more secure”, because in this case, you don’t need to use large 2 W resistors, which get quite hot. Besides. Experimentally, you can adjust the brightness of the LEDs by selecting transistors.

Video of connecting an LED to 12 volts

I understand that most will not understand all this. what is written here. therefore, for those who just want to see and repeat, watch the video, which popularly shows how to connect LEDs to 12 Volt DC.